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EEVblog => EEVblog Specific => Topic started by: EEVblog on July 05, 2012, 04:44:18 am

Title: EEVblog #306 - Jim Williams Pulse Generator
Post by: EEVblog on July 05, 2012, 04:44:18 am
EEVblog #306 - Jim Williams Pulse Generator (https://www.youtube.com/watch?v=F-ZDiGmLvTs#ws)

Dave.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: PeteInTexas on July 05, 2012, 05:26:04 am
I'm curious about hooking it up to your "upgraded" Rigol.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: envisionelec on July 05, 2012, 05:26:23 am
Interesting. I have never seen that App Note. I once generated pulses using the propagation delay of some CMOS gates. I was getting nanosecond pulses with picosecond rise times, shorter than what this generates...and driving an LED circuit for ultra high speed photography where a laser could not be used. The PCB was otherworldly. It was handmade from copper tape and Kapton film and was packaged into a tiny Pomona EMI sealed case.

Applied for the patent at the urging of my co-workers, but someone beat me to the punch just three months prior.  :P
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: EEVblog on July 05, 2012, 05:54:07 am
Interesting. I have never seen that App Note. I once generated pulses using the propagation delay of some CMOS gates. I was getting nanosecond pulses with picosecond rise times, shorter than what this generates...

Circuit?

Dave.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: free_electron on July 05, 2012, 06:26:44 am
hmm. if i have a spare moment i'll breadboard this thingie... i have access to a 16GHz bandwidth scope... let's see what it really does... should be interesting to see.
-edit- i looked at the pcb layout a bit. he's got way too much stray capacitance around the emitter of the transistor. the copper should be peeld back. this thing can go faster ..
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: jahonen on July 05, 2012, 06:58:00 am
I'm not sure if the pulse gives correct rise time figures to calculate the bandwidth. I (and Leo Bodnar) did some experiments in the past, with my 300 MHz and 6 GHz scopes. I got 820 ps rise time for my Agilent MSO6034A:

https://www.eevblog.com/forum/projects-designs-and-technical-stuff/scope-rising-time/msg10635/#msg10635 (https://www.eevblog.com/forum/projects-designs-and-technical-stuff/scope-rising-time/msg10635/#msg10635) (see next posts also)

That would translate to 488 MHz bandwidth (using factor of 0.4) which sounds a bit unrealistic, but using a coax for energy storage to get a true step, gives 1.16 ns which leads to much more realistic value of 345 MHz for a 300MHz scope banner specification.

For a reliable step and rise time measurements, one must replace the capacitor with a piece of coax (preferably with a low-loss rigid type).

Regards,
Janne
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: EEVblog on July 05, 2012, 07:24:43 am
-edit- i looked at the pcb layout a bit. he's got way too much stray capacitance around the emitter of the transistor. the copper should be peeld back. this thing can go faster

I agree. Although I doubt you'll get much faster than what Jim Williams did. This circuit has been much built over the years and I don't recall anyone ever getting anything substantially better than Jim did.
I will be able to measure my actual board soon with a better scope. I don't expect a huge increase in performance by stripping back the ground plane in this instance. But yes, further improvement can be eeked out I'm sure.

Dave.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: mikeselectricstuff on July 05, 2012, 07:38:31 am
Don't forget to ask Agilent if you can try it with one of their higher-end scopes while you're there , assuming they bother keeping any in Oz...!
 
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: peter.mitchell on July 05, 2012, 07:50:40 am
When you "upgrade" a scope, not just via firmware, do they put in some daughter boards or do they do a mac style upgrade?

video related:
Mac Spoofed: OS (https://www.youtube.com/watch?v=O1OfBGfeVkY#)
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: EEVblog on July 05, 2012, 08:09:01 am
Don't forget to ask Agilent if you can try it with one of their higher-end scopes while you're there , assuming they bother keeping any in Oz...!

They do, and one is coming to my lab shortly...

Dave.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: jahonen on July 05, 2012, 08:18:35 am
I'm not sure if the pulse gives correct rise time figures to calculate the bandwidth. I (and Leo Bodnar) did some experiments in the past, with my 300 MHz and 6 GHz scopes. I got 820 ps rise time for my Agilent MSO6034A:

https://www.eevblog.com/forum/projects-designs-and-technical-stuff/scope-rising-time/msg10635/#msg10635 (https://www.eevblog.com/forum/projects-designs-and-technical-stuff/scope-rising-time/msg10635/#msg10635) (see next posts also)

That would translate to 488 MHz bandwidth (using factor of 0.4) which sounds a bit unrealistic, but using a coax for energy storage to get a true step, gives 1.16 ns which leads to much more realistic value of 345 MHz for a 300MHz scope banner specification.

For a reliable step and rise time measurements, one must replace the capacitor with a piece of coax (preferably with a low-loss rigid type).

Regards,
Janne

Just checked the bandwidth using a spectrum analyzer tracking generator, and -3 dB seems to be about at 380 MHz. So 820 ps is definitely too optimistic figure.

Regards,
Janne
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: tnt on July 05, 2012, 08:26:36 am
Don't forget to ask Agilent if you can try it with one of their higher-end scopes while you're there , assuming they bother keeping any in Oz...!

They do, and one is coming to my lab shortly...

Dave.

Great, I must confess I was kind of hoping for this :p

As mentioned by others the pulse is so short that the scope doesn't display it fully (falls before it reached peak). But if you know the "real" pulse shape, and the "measured" pulse shape on the DUT, I'm pretty sure it would be possible to correctly find the bandwidth. The PCB has holes to solder a coax BTW. I tried with 30 m of LMR240 and it worked fine even though it does impair the practicality to have 30 m of coax attached :p


To comment on the other posts:

The output trace is meant to have a 50 ohm impedance, and when using it with a bnc cable I would expect the capacitance of the cable dominates anyway. The layout is certainly not perfect, but it's the first revision of the PCB and it turned out "good enough" for my use so I didn't bother making a second revision.

Btw, the 90V supply is made easily available on a test pad on the PCB so that if you want to do a "jim williams" type of construction on the connector itself, you can reuse the switcher part and only have to worry about the 4-5 components to solder on the BNC.

Cheers,

     Sylvain
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: jahonen on July 05, 2012, 08:52:34 am
Given potential of this circuit, I think it is not probably worth the time to start optimizing the layout much further, although it would be certainly possible to use a 3D EM simulator to optimize the cutouts beneath of each component pad and via to get 50 ohm impedance everywhere in the signal path :) Also, too wide microstrips start to behave in a non-TEM way (which causes a dispersion) when frequency rises enough but that doesn't probably happen until above 10 GHz or so.

Regards,
Janne
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: BravoV on July 05, 2012, 09:19:17 am
Just fyi, saved & bookmarked this info while a go about other transistor that is faster than 2N2369, from this interesting post -> http://www.electronicspoint.com/avalanche-transistors-t212987.html (http://www.electronicspoint.com/avalanche-transistors-t212987.html)

Edit : Datasheet of BFG541 NPN 9 GHz Wideband transistor here -> http://www.nxp.com/documents/data_sheet/BFG541_CNV.pdf (http://www.nxp.com/documents/data_sheet/BFG541_CNV.pdf)

Quote

The subject of avalanche-mode pulse generators comes up here now and again. A colleague pointed out to me that a Philips BFG541 transistor will avalanche nicely at around 50V or so.

Confirmed. It's quite fast too: I measured a 150ps risetime, using a Tek S-6 sampler plugin in a 7000 series mainframe. It's a little over twice as fast as the 2n2369 I usually select for this purpose.

 I thought some people around here might like to know...

 Anyone here know any other transistors that will also avalanche fast? (I know of Zetex. Not so great.)

 Jeroen Belleman

Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: Omicron on July 05, 2012, 09:30:39 am
This circuit pops up now and then. But the thing is: you can't use it for bandwidth measurements! The formula used is only valid if the pulse is wide enough for the oscilloscope to reach the actual signal amplitude. This has been discussed before on the forum I think. This particular pulse is too fast for the scope to show the correct amplitude. The "rise time" you measure this way is meaningless, the scope never reaches the 90% point. Rise time is not 10% to 90% of what you see on the screen, it's 10% to 90% of what actual signal amplitude is there at the input!

I believe that in later application notes Jim provides circuits that generate much longer pulses.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: tnt on July 05, 2012, 09:44:38 am
As Janne and I mentionned above, in a latter app note you have the same circuit but using a coax hardline as energy storage and this creates more of a 'step' than a pulse. Just need to solder a coax at the right place, but it makes it a bit impractical.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: Omicron on July 05, 2012, 09:54:07 am
Indeed, I recall the use of the hard line.

Also, you have to remember that Agilent and Tek always specify bandwidth of the entire system, i.e. including the probes they provide with the scope. So if you measure the bandwidth of the scope itself on the 50 Ohms input you should measure a bandwidth that is slightly larger. 345MHz seems perfectly on spec for a 300MHz scope.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: EEVblog on July 05, 2012, 10:12:57 am
As mentioned by others the pulse is so short that the scope doesn't display it fully (falls before it reached peak). But if you know the "real" pulse shape, and the "measured" pulse shape on the DUT, I'm pretty sure it would be possible to correctly find the bandwidth.

What needs to be remembered also, is that you can't overestimate your bandwidth with this. So at worst, whatever the circumstances, your scope will have a better bandwidth than what you measure  :)

Dave.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: nitro2k01 on July 05, 2012, 10:48:51 am
Couldn't you do a quick bodge and put a small piece of wire between the female connectors? (Bare wire, so short that you can make the shields touch.)
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: dda on July 05, 2012, 11:54:33 am
As mentioned by others the pulse is so short that the scope doesn't display it fully (falls before it reached peak). But if you know the "real" pulse shape, and the "measured" pulse shape on the DUT, I'm pretty sure it would be possible to correctly find the bandwidth.

What needs to be remembered also, is that you can't overestimate your bandwidth with this. So at worst, whatever the circumstances, your scope will have a better bandwidth than what you measure  :)

Dave.

If the peak begins to fall before the scope can detect it, isnt the 'true' rise time underestimated, and thus dividing 0.35 by a smaller number means BW is larger and so is overestimated?
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: Omicron on July 05, 2012, 11:57:52 am
What needs to be remembered also, is that you can't overestimate your bandwidth with this. So at worst, whatever the circumstances, your scope will have a better bandwidth than what you measure  :)

Dave.
Actually that is not true. If you measure your bandwidth using the rise time obtained from the narrow pulse your estimate is always going to be way too high. For example see the number Jahonen obtained for the 300MHz scope. The reason is that what you read as the "rise time" is too low because in reality the curve should have been allowed to continue to the actual amplitude of the input signal. You never reach this real 90% point and what you think is the 90% point from what you see on the screen is happening way too early. Or in other terms: the higher the amplitude of the input pulse, the higher your bandwidth reading is going to be.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: jahonen on July 05, 2012, 01:54:58 pm
What needs to be remembered also, is that you can't overestimate your bandwidth with this. So at worst, whatever the circumstances, your scope will have a better bandwidth than what you measure  :)

Dave.
Actually that is not true. If you measure your bandwidth using the rise time obtained from the narrow pulse your estimate is always going to be way too high. For example see the number Jahonen obtained for the 300MHz scope. The reason is that what you read as the "rise time" is too low because in reality the curve should have been allowed to continue to the actual amplitude of the input signal. You never reach this real 90% point and what you think is the 90% point from what you see on the screen is happening way too early. Or in other terms: the higher the amplitude of the input pulse, the higher your bandwidth reading is going to be.

I have also noticed that if one performs an integration of the pulse with a scope integration math function and then measures the rise time of this integrated pulse (a step), the resulting figure is much closer to the real value (this might be indeed pessimistic). But I guess that this requires that the pulse is much faster than the scope.

Out of interest, I measured the spectrum of the pulser output signal. It seems that it could be flatter, but that is probably ok'ish up to something like 500 MHz or so, depending on the criteria. Certainly adequate for 100 MHz or so. First roll-off seems to begin quite early.

(https://www.eevblog.com/forum/blog-specific/eevblog-306-jim-williams-pulse-generator/?action=dlattach;attach=26761;image)

Regards,
Janne
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: free_electron on July 05, 2012, 03:37:22 pm


The output trace is meant to have a 50 ohm impedance, and when using it with a bnc cable I would expect the capacitance of the cable .


I am going to build it dead bug style.
The problems with the are the following :
 - you have ground on the top layer around the emitter. That should not be there. The 50 ohms is made between top and bottom layer, not on the layer itself. Any ground on top layer froms stray capacitance
- the pins of the transistor sit in pads that go through the board. This gives again stray capacitance , inductance and it forms also an unterminated antenna.

I will flip the transistor upside down , solder the case to a chunk of copper , solder an end-launch sma close to it , put two 100 ohm smd resistors in 'tombstone' and bend the emitter wire so it laus on top of the resistors and touches the center pin of the sma. That way the whole emitter node is floating. Nothing is sticking out.

For a second revision of the board you can do that easily.
Drill a round hole in the pcb so you can drop the body of the transistor in th hole with the legs sticking up. And provide only smd pads to solder the transistor wires.

I'll whip up a drawing of what i mean later today. Off to the local junkshop to get some of those transistors. They have 1800 in stock...
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: tnt on July 05, 2012, 08:39:57 pm
Hi,

I did a few tests and I think the results are pretty interesting.

First a description of the equipement involved:

 - Rigol 1052E modified for 100 MHz
 - Agilent 3000-X 350 MHz
 - Agilent 3000-X 500 MHz

 - E4433B 4GHz RF signal generator

 - Pulse generator
 - Pulse generator + 1m RG402 semirigid coax as energy storage (see picture)


The first test I did was to get the 'true' -3dB bandwidth of the scopes by first feeding them a known amplitude 10 MHz signal and then rising the frequency until I reached a 3 dB attenuation. Results are as follow:

 - Rigol 1052E mod 100 MHz => 115 MHz
 - Agilent 3000-X 350 MHz  => 405 MHz
 - Agilent 3000-X 500 MHz  => 650 MHz


I then measured the rise time with the pulse generator alone:

 - Rigol 1052E mod 100 MHz => 1.28 ns ( ~ 273 MHz using 0.35 / t_r)
 - Agilent 3000-X 350 MHz  => 0.71 ns ( ~ 560 MHz using 0.4 / t_r)
 - Agilent 3000-X 500 MHz  => 0.54 ns ( ~ 740 MHz using 0.4 / t_r)

As you see the bandwidth is too high (I used gaussian model for the rigol and the maximally flat model for the Agilent), as several people pointed out, the pulse is too short and so can't be measure accurately by low bandwidth scope. The more bandwidth you have the closer you get to reality but for low-end scope it's _way_ over estimated !

I then tested to measure the rise time of the integral of the signal using the math function as Janne suggested. The rigol doesn't have this so it's only for the agilent:

 - Agilent 3000-X 350 MHz  => 1.15 ns ( ~ 350 MHz using 0.4 / t_r)
 - Agilent 3000-X 500 MHz  => 0.76 ns ( ~ 530 MHz using 0.4 / t_r)

It's more realistic but this time it's a bit too pessimistic (altough not that much, see later) but it could just be dumb luck ... more samples needed.

On the PCB, I left pads to solder a coax hardline as Jim Williams describes in a later app note, so here I soldered 1m of RG402 semirigid coax to it.

 - Rigol 1052E mod 100 MHz => 2.85 ns ( ~ 120 MHz using 0.35 / t_r)
 - Agilent 3000-X 500 MHz  => 0.73 ns ( ~ 550 MHz using 0.4 / t_r)

As you can see the Rigol is pretty much spot on, but the Agilent result is too pessimistic ...

However we must remember that the pulse generator itself has a ~ 350 ps rise time, and so the total system rise time is defined as :

t_sys ^ 2 = t_scope ^ 2 + t_pulsegen ^ 2

and so if t_sys = 0.73 ns  and  t_pulsegen = 0.35 ns  we get that the scope rise time must be 0.64 ns which correspond to an approximate bandwidth of 625 MHz which is what was expected.

So all in all I would say:

 - Add a coax hardline (15 cm should be enough) and that allows to really measure the scope bandwidth
 - Take the pulse gen into account for anything expected to be > 350 MHz.
 - Ideally known the caracteristics of your particular pulse gen to compensate for them as accurately as possible.

Cheers,

    Sylvain
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: Lukas on July 05, 2012, 09:29:49 pm
Why are you all fiddling around with avalanche pulse generators? We're not in the '60s anymore!
PECL gates such as the MC100EPT20 provide 120ps rise/fall time in a convenient SO8 package without arcane dead bug technology. Just put one on a PCB with two SMA connectors, hook it up to 3.3V and feed it with the input of a signal generator or include an oscillator on the PCB. When 120ps aren't enough, there are gates with 30ps rise/fall time, such as the NBSG11 (very expensive, free samples). Very fast comparators also have output drivers that produce fast edges.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: free_electron on July 06, 2012, 12:12:57 am
Here's a quick layout ( still needs work ... )
Small case using a cr2032 coin cell. Basically the same schematic from AN47.
I have a 5mm hole in 6mm pad in the PCb to solder the TO18 body upside down. The collector of this transistor is connected to the case ( i cut one open and doublechecked as well as ohmed it out ) So the case of the transitor gets the 1M /2pF node

Soldermask has been removed in that area to avoid leakage.

The base leg of the transistor is bent down to an SMD pad that goes with 10K to ground. The emitter is bent towards the SMA connector. A 1206 50 resistor is mounted on-end on an SMD pad. The emitter leg lies on top of the other electrode of the 1206. Two dabs of solder and you have a perfect flying lead line there. No leakage anywhere and mechanically robust.

Fits in a little case with a slide on/off switch and LED that tells you its on.

I could not really find Male BNC plugs that solder directly on PCB.  And the high end scopes have SMA inputs... the SMA end launch connector is the right height to pull off the trick with the 1206 standing on end.
So compromise : screw on an SMA to BNC adapter and you can plug this straight into a 'low end' scope input.
for the really speed deamons : use an SMA-SMA male-male connector.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: w2aew on July 06, 2012, 03:28:39 am
Hey tnt - do you have any more of the PCBs for this pulse generator?
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: vk6zgo on July 06, 2012, 04:19:46 am
Looking at the shape of the pulse,it looks a lot like the sin^2 pulses we used to test TV system video response.
Back in the day,they used rectangular pulses,but problems with ringing made them less than perfect for the job.
The sin^2 pulse provides a much more repeatable test result.
There was a fair bit written up  about this by J.E.Weaver,& others.
The relationships are different to simple rise time,but that's about all I can remember about the niceties of it all,at this remove.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: tnt on July 06, 2012, 05:49:55 am
@free_electron: Nice assembly :) Looking forward to see it built.

@Lukas: For fun ? There is still much to be learned from how this circuit work IMHO (even just from the stepup for eg, that uses a trick to overcome the limitation of the stepup controller, or from the constructions techniques involved here, ...). Also, doesn't PECL have a pretty limited swing ? Some circuits might behave differently in small signal vs large signal (here the pulse is ~ 10V in 50 ohm).
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: free_electron on July 06, 2012, 06:17:57 am
Pecl is about 800mV and is differential. Single ended it swings only 400mV. And does. Ot go to zero. Centerpoint is 1.65 volt.

The JW pulser does 10 volts or so...
I'm going to tweak the layout a bit more over the weekend. I need to move the 2pF cap so one electrode touches the body of the to. I will place additional cap footprints in a circle around the to-18 body so we can play with the cap value.

Will send pcb to itead to run
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: BravoV on July 06, 2012, 06:44:17 am
Just a noob question regarding PECL vs Avalanche type's slew rate, I thought avalanche type range is in GigaVolt/second which is much-much higher than PECL ?

CMIIW
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: blackdog on July 06, 2012, 07:45:19 am
Hi Free_electron

Cant you make the emittor shorter en use 2x 100 Ohm parr on the output, maybe less ringing?

Just 2 cents..

Bram
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: EEVblog on July 06, 2012, 10:16:26 am
Where is this app note that shows the coax mod? anyone know the number?

Dave.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: jahonen on July 06, 2012, 10:19:19 am
Where is this app note that shows the coax mod? anyone know the number?

Dave.

AN94 seems to have one, at least.

Regards,
Janne
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: eV1Te on July 06, 2012, 11:36:35 am
Does anyone know good tunneling diodes for achieving <100 ps rise times? The only tunnel diode I found at my local electronics store was the 1N3716, although this particular diode does not seem to be optimized for fast rise times (but I could not find typical values for the tunneling speed in the datasheet).

I also found the shortcut way to making ~40 ps rise/fall-time generator with the Silicon Germanium ADCMP580 comparator (built in 50 ohm resistor and drive capability)  :P
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: Neganur on July 06, 2012, 12:38:02 pm
You could try these from ebay:

1I308J tunnel diodes 2pcs (http://www.ebay.com/itm/1I308J-tunnel-diodes-2pcs-NEW-/221060444411?pt=LH_DefaultDomain_0&hash=item33783ab0fb)

They're supposedly russian Germanium tunnel diodes with 20mA peak point current and 1...4 pF valley point terminal capacitance. Less than 100 ps could be possible with these. Fast tunnel diodes are very rare, and very expensive.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: vk6zgo on July 06, 2012, 01:09:39 pm
The old Tektronix TU-5 Pulser used a tunnel diode.
We used these to check our 545B 'scopes back in the day.
They had to be fed with a high voltage square wave--The 545B Cal signal was switchable up to 100volts.
When the tunnel diode operated,it produced a very fast rise time leading edge on a very attenuated version of the input sq wave.
I don't remember how fast it was--after all we were testing 545Bs with it,so it didn't have to be that spectacular!
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: eV1Te on July 06, 2012, 01:18:19 pm
You could try these from ebay:

1I308J tunnel diodes 2pcs (http://www.ebay.com/itm/1I308J-tunnel-diodes-2pcs-NEW-/221060444411?pt=LH_DefaultDomain_0&hash=item33783ab0fb)

They're supposedly russian Germanium tunnel diodes with 20mA peak point current and 1...4 pF valley point terminal capacitance. Less than 100 ps could be possible with these. Fast tunnel diodes are very rare, and very expensive.
Interesting, it seems like tunnel diodes are quite common on ebay, you can even find ones with <1 pF terminal capacitance for just a few dollars each. Unfortunately I don't have access to equipment capable of measuring the performance if I would try and build a step generator with them.

It would also be interesting to compare the performance of the pulse generator to a mechanical switch (preferably a mercury switch) which apparently also can go as low as 70 ps.

What is the rise-time if one mechanically touches the legs of a charged small ceramic cap to the input of the scope?

The old Tektronix TU-5 Pulser used a tunnel diode.
We used these to check our 545B 'scopes back in the day.
They had to be fed with a high voltage square wave--The 545B Cal signal was switchable up to 100volts.
When the tunnel diode operated,it produced a very fast rise time leading edge on a very attenuated version of the input sq wave.
I don't remember how fast it was--after all we were testing 545Bs with it,so it didn't have to be that spectacular!

I've seen tunnel diode step generators that have rise-times below 10 ps, but more common is around 30 ps. Unfortunately the amplitude you get is only as large as the tunneling zone (~300 mV).
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: vk6zgo on July 06, 2012, 01:43:46 pm
I found the details of the TU-5 here-:www.diybanter.com/.../4131d1223498570-tek-tu-5-td-pulser-tu-5-p..
It is quite a lot slower at 1.5nS.
It's still good for about 233mHz,unless I got my sums wrong!
OK for the 545Bs,which If I remember correctly,were supposed to be 35Mhz at the -3dB point,although they could see about twice that.
I remember looking at CH2 Vision & sound carriers with one,at different times.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: tecman on July 06, 2012, 03:09:40 pm
Here's a quick layout ( still needs work ... )
Small case using a cr2032 coin cell. Basically the same schematic from AN47.

Fits in a little case with a slide on/off switch and LED that tells you its on.

Free_electron:

If you finish it up are you thinking about selling a few of them ?  I would buy one since I do not want the hassle of working from scratch.


Dave:  what about the design you have ?  Are they available for purchase from someone ?


I would be interested in one for the bench.


paul
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: free_electron on July 06, 2012, 03:28:13 pm

Free_electron
If you finish it up are you thinking about selling a few of them ?  I would buy one since I do not want the hassle of working
[/quote]
I'll have spare boards yes. I can sell blank boards.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: samarkh on July 06, 2012, 03:50:25 pm
Could you show this being used as a tdr (Time Domain Reflexometer )? To show cable impedance mismatch / breaks / shorts and the like?

Yours Simon M.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: free_electron on July 06, 2012, 04:02:21 pm
For tdr you really need a step as opposed to a pulse.... But i guess a pulse could work too as long as the reflected energy does not come back before the pulse has decayed
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: robrenz on July 06, 2012, 04:39:05 pm
Could you show this being used as a tdr (Time Domain Reflexometer )? To show cable impedance mismatch / breaks / shorts and the like?

Yours Simon M.

w2aew's video on that
Use a scope to measure the length and impedance of coax (https://www.youtube.com/watch?v=Il_eju4D_TM#)
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: Pat Pending on July 06, 2012, 04:45:46 pm
I didn't hear it mentioned, but was Daves Agilent scope set for 50R input?
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: Lukas on July 06, 2012, 07:16:48 pm
I don't think that 10Vpp output is desirable. The maximum vertical scale of my fastest 'scope (7A19 in 7834) is 1V/div. Some very fast 'scopes such as the Agilent 90000A series have an input voltage range of only ±5V. All in all, around 400mVpp is more appropriate today than 10V. Of course, you may use attenuators, but that's another thing in the signal path that may decrease signal integrity.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: Alexei.Polkhanov on July 06, 2012, 09:58:29 pm
You could try these from ebay:

1I308J tunnel diodes 2pcs (http://www.ebay.com/itm/1I308J-tunnel-diodes-2pcs-NEW-/221060444411?pt=LH_DefaultDomain_0&hash=item33783ab0fb)

They're supposedly russian Germanium tunnel diodes with 20mA peak point current and 1...4 pF valley point terminal capacitance. Less than 100 ps could be possible with these. Fast tunnel diodes are very rare, and very expensive.
I got 6 of those from same seller on ebay 2 months ago for laser distance measuring project that I was planning. I checked one diode for basic diode action when I got the package - it is fine, but I have a problem however - I need a holder for these tiny devices. Germanium ... most likely not solderable at all. No clue where I can get nice holders. I soldered a needle to a small pad and tried to use it - looks like I need something better than that and preferably gold plated. Also I am scared to touch them even with wrist band on - they must be uber sensitive to ESD.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: G7PSK on July 07, 2012, 08:56:50 am
You could try these from ebay:

1I308J tunnel diodes 2pcs (http://www.ebay.com/itm/1I308J-tunnel-diodes-2pcs-NEW-/221060444411?pt=LH_DefaultDomain_0&hash=item33783ab0fb)

They're supposedly russian Germanium tunnel diodes with 20mA peak point current and 1...4 pF valley point terminal capacitance. Less than 100 ps could be possible with these. Fast tunnel diodes are very rare, and very expensive.
I got 6 of those from same seller on ebay 2 months ago for laser distance measuring project that I was planning. I checked one diode for basic diode action when I got the package - it is fine, but I have a problem however - I need a holder for these tiny devices. Germanium ... most likely not solderable at all. No clue where I can get nice holders. I soldered a needle to a small pad and tried to use it - looks like I need something better than that and preferably gold plated. Also I am scared to touch them even with wrist band on - they must be uber sensitive to ESD.

Woods metal. It melts at little over blood heat  70 deg C and was often used for mounting germanium in the past. There are alloy metal that melts even lower.   http://en.wikipedia.org/wiki/Wood's_metal (http://en.wikipedia.org/wiki/Wood's_metal)
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: PChi on July 07, 2012, 10:46:59 am
I have just tried using an old SGS BC549C VCBO and VCEO = 30 V maximum which I happened to have in a copy of the avalanche part of the circuit. It didn't avalanche at 120 V which is where I ran out of courage. So just confirming that the transistor type and particular sample are important.

Another factor to consider is that the formula relating rise time and bandwidth assumes that there is no large signal / slew rate limitation.

I'm not sure how much I trust digital oscilloscopes near their bandwidth limitation. Older models had the ability to turn off the curve smoothing and just show the raw samples on the screen. In the single sweep mode it was informative to show the sample points and then to show the smoothed curve.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: max-bit on July 07, 2012, 10:48:00 am
Hi This is my first post :) Gentlemen, if you want I can arrange a lot of transistors 2n2369A Production Motorola and Philips (years of production 80 - 90) Are desoldering Motorola, Philips is not soldered Price 1.5 USD plus shipping and handling.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: alm on July 07, 2012, 01:14:12 pm
However we must remember that the pulse generator itself has a ~ 350 ps rise time, and so the total system rise time is defined as :

t_sys ^ 2 = t_scope ^ 2 + t_pulsegen ^ 2

and so if t_sys = 0.73 ns  and  t_pulsegen = 0.35 ns  we get that the scope rise time must be 0.64 ns which correspond to an approximate bandwidth of 625 MHz which is what was expected.
Note that this formula only applies if all parts of the system have a Gaussian response. For maximally flat response, I believe Agilent's suggestion in an appnote is 'ask the manufacturer', since it's quite rare for scope vendors to publish bode plots of the scope response.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: free_electron on July 08, 2012, 12:26:25 am
Right. Here's a promised update:

(http://www.siliconvalleygarage.com/eevblog/pulsegen/3d0.jpg)
Final design.
Deviation from the JW schematic : i use a CR2032 coincell and have two additionla 1-uf Ceramic caps around the LT1073.

(http://www.siliconvalleygarage.com/eevblog/pulsegen/3d2.jpg)
The @n2369 is mounted Dead-bug style in a hole drilled in the PCB. The cae of this transsitor is electrically connected to the Collector. so the hole has the 1 Megaohm and 2pF caps connected to it. The collector wire is simply snipped of , or can be tacket to the rim of the case.
The base wire is bent outwards and down to land on an SMD pad to the 10k base resistor.

(http://www.siliconvalleygarage.com/eevblog/pulsegen/3d1.jpg)
the 50 ohm resistor is made with two 100 ohms 1206 body resistors soldered back to back and vertically. A standard through hole SMA connector is put on edge and soldered on the board.

The emitter wire is bent out form the to-18 can and lies on top of the resistors electrode and contacts the center pin of the SMA. Two dabs of solder do the rest. The goal wa ot minimize stray capacitance as much as possible. I also opened the soldermask around the critical area's to avoid leakage there.

Copper features with soldermask removed :

(http://www.siliconvalleygarage.com/eevblog/pulsegen/front.jpg)
(http://www.siliconvalleygarage.com/eevblog/pulsegen/back.jpg)

The loop on the back is intentional. This is the feedback point of the voltage divider. I do not want that running underneath the switching inductor as it would pick up the field , so it 'detours'. that point is high impedant.

Everything fits in a Hammond case model 1553AABK or 1553AAGY. All the cutouts and mounting holes are present in the PCB.
All parts are available from digikey apart from the 2n2369.

I will order the PCB tomorrow from IteadStudio. I'll have a few extra's. If anyone is interested. 5$ gets you a blank PCB (US shipping included). I order the 10x5 cm as this board is 6.5 by 5. And go for the color version (i don't like green boards. I'm colorblind and don't see green. They are grey to me ... dull and drab. I may go with yellow soldermask and black text ... or Blue and white ). Shipping will be done to me from itead using UPS. I don't want to wait an unknown amount of weeks to get this.

I will probably order parts from digikey in quantity a well ( no point in buying 3 diodes.... ) So if anyone is interested in the full kit.
I have to calculate what the final would be. I have 2n2369 plenty. I'll throw in 2 or 3 per kit.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: krivx on July 08, 2012, 01:42:20 am
Looks like a really nice layout. I think I would like a full kit  :)
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: chavotronic on July 08, 2012, 08:16:20 am
One thing i don't get with the rise time / BW formula.
How can this only be dependent on the rise time, and not the rise time AND the amplitude (the slope).
I would guess that with a higher amplitude, your rise time is higher even with the same rising slope.
Would be nice to have an answer to that.
David
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: G7PSK on July 08, 2012, 09:31:26 am
Hi Free Electron, I would like to buy a full kit please. Are you willing to ship to the UK though, if you are you have sold one, many thanks. G7PSK
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: BravoV on July 08, 2012, 09:37:42 am
FE, count me in for one kit.

PS : Suggesting you to create new thread for it in the "Buy/Sell/Wanted" sub-forum.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: vk6zgo on July 08, 2012, 11:31:27 am
One thing i don't get with the rise time / BW formula.
How can this only be dependent on the rise time, and not the rise time AND the amplitude (the slope).
I would guess that with a higher amplitude, your rise time is higher even with the same rising slope.
Would be nice to have an answer to that.
David
No,the rise time is defined as the time between 10% & 90% of the final amplitude of the signal at any signal amplitude.
It is the percentage change,which defines the slope,not the absolute value.
Think about ordinary swept frequency response--this is not affected by the signal amplitude,so why should rise time be any different?

Rise time is unaffected by changes in amplitude,if a perfect attenuator or amplifier is used.
Real attenuators & amplifiers have a response of their own,which will affect the  rise time of the signal after passing through them.
The rise time is worse after passing through these devices.
You can improve the rise time of a rectangular or square wave by"clipping" the signal at some level which is reached earlier on the leading edge of the signal.

Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: tecman on July 08, 2012, 12:36:46 pm
I will take a full kit as well.

paul
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: HackedFridgeMagnet on July 08, 2012, 12:51:45 pm
Dave you mentioned RG59 at just before 7 minutes, you must've meant rg58.

I'll take one Free Electron and postage to Oz if possible.
What case are you using? I'll go in for a case too if possible.


Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: all_repair on July 08, 2012, 01:18:50 pm
Count me one for a full kit if possible with case to Singapore.  Thanks !!!
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: dbinokc on July 08, 2012, 01:42:43 pm
I just signed up for the forum just so I could say count me in as well for one.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: Alexei.Polkhanov on July 08, 2012, 09:52:24 pm
You could try these from ebay:

1I308J tunnel diodes 2pcs (http://www.ebay.com/itm/1I308J-tunnel-diodes-2pcs-NEW-/221060444411?pt=LH_DefaultDomain_0&hash=item33783ab0fb)

They're supposedly russian Germanium tunnel diodes with 20mA peak point current and 1...4 pF valley point terminal capacitance. Less than 100 ps could be possible with these. Fast tunnel diodes are very rare, and very expensive.
I got 6 of those from same seller on ebay 2 months ago for laser distance measuring project that I was planning. I checked one diode for basic diode action when I got the package - it is fine, but I have a problem however - I need a holder for these tiny devices. Germanium ... most likely not solderable at all. No clue where I can get nice holders. I soldered a needle to a small pad and tried to use it - looks like I need something better than that and preferably gold plated. Also I am scared to touch them even with wrist band on - they must be uber sensitive to ESD.

Woods metal. It melts at little over blood heat  70 deg C and was often used for mounting germanium in the past. There are alloy metal that melts even lower.   http://en.wikipedia.org/wiki/Wood's_metal (http://en.wikipedia.org/wiki/Wood's_metal)
Fact that they have lo leads probably means they never meant to be soldered. Kind of like those gunn diodes that go into special fixture inside microwave horn I guess.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: robrenz on July 08, 2012, 11:14:47 pm
Count me in for a kit also.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: Alexei.Polkhanov on July 09, 2012, 01:40:21 am
I will probably order parts from digikey in quantity a well ( no point in buying 3 diodes.... ) So if anyone is interested in the full kit.
I have to calculate what the final would be. I have 2n2369 plenty. I'll throw in 2 or 3 per kit.

I don't understand what is necessity of taking gamble with these 2N2369 devices and "hand-picking" them when choice of specialized avalanche action transistors available like FMMT413 from Zetex. 50V breakdown voltage - should work in this design as well and it is in SMD package.
DigiKey: http://www.digikey.ca/product-detail/en/FMMT413TD/FMMT413TDCT-ND/2248551 (http://www.digikey.ca/product-detail/en/FMMT413TD/FMMT413TDCT-ND/2248551)
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: free_electron on July 09, 2012, 03:06:17 am
There's a couple of things at play

First of all the 2n2369 is NOT a true avalanche transistor. It is just being used in avalanche mode ( which is actually a bad idea ... unless the current is critically limited this would normally fry a transistor )

Avalanche mode operation is actually a controlled breakdown of the Vceo voltage. the collector voltage is so high that it it succeeds in pulling electrons from the emitter through the base region. The transistor enters conduction and you get a snowball effect. the high collector voltage causes the transistor to start conducting all by itself.

Real avalance transistors, in real avalanching applications such as laser drivers are held just under this point . The little extra energy that is required is created by pulling the base high. this gets the electrons shot in the emitter and they race towards the collector en-masse. there is suc h a thing as secondary avalanche but i'd have to look it up.. can't remember the exact physics.

Any transistor can be made to avalanche. It's just a matter of finding the right voltage and limiting the current so you don't fry it.
I did some poking around and there are other transisotrs that will perform very well in this pulse generator like the BFG541 and the ZTX415.

The problem with true avalanche transistors is that they are pricey .... 7 to 15 $ ... a pop... while a 2n2369 costs 0.5$ ...
Anyway , this circuit has enough room for experimentation. if anyone wants to have a go at true avalanche transistors be my guest.

Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: BravoV on July 09, 2012, 03:33:06 am
Btw the BFG541 cost just $0.5 and its in SOT223 form, I guess we could even solder it with the cap + resistors straight at the at back of the bnc connector.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: Alexei.Polkhanov on July 09, 2012, 05:55:16 am
BFG541  is not designed for avalanche action. It is a same story as with 2N2369 - avalanche action is a side effect of what otherwise sold as regular transistor. I think BFG541 has to be "hand-picked" in same way as 2N2369. I see people raising concerns about how long these transistors will survive if used for avalanche action continuously like in case of laser distance meter for example.
 
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: free_electron on July 09, 2012, 06:09:44 am
True . those transistors are not designed for avalanche operation, but then a true Avalanche transisotr is not meant to be used in this fashion either.
A true avalanche transistor is 'ignited' by a base pulse that starts conduction by pulling electrons from the emitter to the base and opening the channel.

What this 'pulser' system is doing is causing avalanche by pulling the collector above the breakdown voltage and ignite the avalanche that way. No transistor is meant to be used that way. The energy that is dissipated is small due to the fact we only have a 2pF reservoir and we can only feed current through a 1 Megaohm resistor.
Short term it is no more destructive to the transistor than trying to find what is Vceo using a curve tracer. Long term .. your guess is as good as mine.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: GK on July 10, 2012, 01:12:02 am
Datasheets for transistors marketed for avalanche operation actually spec max pulse peak collector current under such conditions - for example 50A (25A secondary breakdown) for the FMMT413.

Shouldn't that imply that these transistors are specifically designed to be robust and long term reliable in this regard?

The FMMT413 datasheet also gives nano farads of external C-E capacitance as a test condition, which is a lot more than 2pF. With only 2pF and "ordinary" small signal transistor in this application is probably more than safe.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: free_electron on July 10, 2012, 03:02:32 am
Datasheets for transistors marketed for avalanche operation actually spec max pulse peak collector current under such conditions - for example 50A (25A secondary breakdown) for the FMMT413.

Shouldn't that imply that these transistors are specifically designed to be robust and long term reliable in this regard?

The FMMT413 datasheet also gives nano farads of external C-E capacitance as a test condition, which is a lot more than 2pF. With only 2pF and "ordinary" small signal transistor in this application is probably more than safe.
True , avalanche transsitors are made fur such behavior. Note that they are intended to be driven into avalanching by pulling the base up , not by overloading the Vceo breakdown voltage ! No transistor is happy in that.

witht he few picofarads the the non avalnche transistors will survivie. Avalannche breakdown is one of the tests done using curve tracers. Then again , you do that during the design of the transisotr on a few thousand  samples to get a spread and set the safe operating margins.

I'd have to talk to our transistor people but i beleive the physical construction of an avalanche transisotr differs from a regular in the sense that the CE channel is much wider, for a same base doping, than in a regular transistor. Like you said. in avalanche the current can be quite high.

Strange beasties..

anyway. It's a Jim williams design. He knew what he was doing. And the idea is to have a pulse generator to compare scopes. You can always install the BFG or the FMMT on the board.
the BFG will fit as its big tab is collector. poke it in the hole , tack it down with solder and connect emitter and base in floating style.
the fmmt is trickier as that is a tiny sot23. but its doable.

Boards are in production since this morning...
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: notsob on July 10, 2012, 03:33:42 am
Count me in for a kit also.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: Alexei.Polkhanov on July 10, 2012, 08:17:14 am
Here is the link to a Masters thesis from Oulu university. There on page 33 (chapter 3.4.3) there is along description of many experiments  with laser and avalanche pulse generator, including current measurements etc. Guy definitely had access to good equipment. http://herkules.oulu.fi/isbn9514272625/isbn9514272625.pdf (http://herkules.oulu.fi/isbn9514272625/isbn9514272625.pdf).


Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: carpin on July 10, 2012, 10:19:00 am
Count me one for a full kit to the Netherlands.
Thanks
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: GK on July 11, 2012, 02:44:17 am
True , avalanche transsitors are made fur such behavior. Note that they are intended to be driven into avalanching by pulling the base up , not by overloading the Vceo breakdown voltage ! No transistor is happy in that.


Hmm, I'm not sure about that. See the Zetex app note here:

http://www.diodes.com/_files/products_appnote_pdfs/zetex/an8.pdf (http://www.diodes.com/_files/products_appnote_pdfs/zetex/an8.pdf)

The series stack configuration for high voltage pulses, as detailed in that app note, rely on Vceo breakdown of all the transistors with the exception of the one fired.

An interesting note in the 4kV stack design paper I linked to a few post back, on the 2n5551, is that they found the Vceo breakdown subject to significant drift in operation, and had to subject the transistors to months of cooking in the test jig to stabilise them.
I wonder if these dedicated avalanche transistors like the FMMT's are pre cooked at the factory - might explain in part the price premium.

 
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: free_electron on July 11, 2012, 05:39:19 am
@gk. interesting reading material.
So it does look like they trigger one, that one avalanches thus the voltage on ce. Becomes next to nothing which means the other guys actually see their vceo go up beyond Bvces so they avalance.

Hmmm. Interesting. Cool, i learned something.   Very oddball parts apparently.
I wonder if there is a typo in that document. They claim trsting to 4x 1011.. Strange number unless the 11 need to be an exponent. 4x 10^11 or 4E11.. It would be odd to do a lifetime testing with 4044 pulses....
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: Nermash on July 11, 2012, 06:45:30 pm
Here is something for all those who hate waiting for pcbs and just don't have that required 2N2369 in the junk box :)

Old faithfull BC547B in FSMT (Flying Surface Mount Technology - as originated by Robert Lacoste in his book "The darker side" 8)) deployment, connected to +170 V DC Nixie supply that I am tinkering with at the moment, and with 470k current limiter.

Captured using Owon SDS7102 100 MHz DSO. I am guessing that excessive amount of ringing on the trailing edge is due to using the standard ground lead. I will probably try connecting it with 1 m of coax...
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: jdesbonnet on July 16, 2012, 10:51:17 pm
Just got a a small selection of low cost, low voltage RF BJT transistors to see what might avalanche. So far just got around to testing two individual devices:  1 x 2DD2661 with a nominal V(br)ceo = 12V. Tested up to Vce of 80V, no joy.

1 x BFG424F with nominal V(br)ceo=4.5V: got avalanching at about Vce = 30V.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: Rufus on July 17, 2012, 02:10:41 am
I had a quick play around, not that my 200MHz x3000 is fast enough to know what is going on.

A transistor socket soldered between two SMA sockets, 15k from base to ground. On the collector about 3 feet of rigid coax fed with 250vdc from an insulation tester via 1M. On the emitter a 10db attenuator and coax to the 50 ohm input on the scope. If I got the probe settings right the traces show what is on the emitter.

I only tried about 10 transistors so far and about 2/3rds avalanched. The traces are from a BC184B. The pulse amplitude depends on the transistor and jitters a lot. The pulse width was very stable. The rise before the pulse is I guess leakage before avalanche and varied with transistor. Not sure what is going on with the fall after the pulse.

Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: free_electron on July 24, 2012, 05:09:04 pm
Boards came in yesterday from itead. Parts from digikey should arrive today.
(http://www.siliconvalleygarage.com/eevblog/pulsegen/pulsegen.png)

i will build one somewhere this week and assemble the kits.
i have 8 spare boards. The kits will appear on ebay and you can order there using paypal. That solves all payment / currecny exchange problems.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: carpin on July 24, 2012, 06:19:58 pm
The board looks great, the track length from the transistor to the bnc is short, exactly what Williams did.

 
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: max-bit on August 01, 2012, 04:26:40 pm
FREE_ELECTRON :) Only one, the question ?
 Did you test pulse generator at a voltage of 3 V power supply? When power is above 1.6 - 1.7 V, the inverter is not stable and at a voltage of 1.8 V the current reaches 0.8 A!!!
 Here is a video: (test)
The problem above 1.6 V power supply Pulse Generator (https://www.youtube.com/watch?v=kQOmchUPKjI#ws)

 I do not know, maybe the fault of the elements used (coil? DIODs), but they are consistent with the specification.
 And so can not supply the "Pulse Generator", directly from the lithium battery?
 Please test whether other models of the LT1073 (DC-DC converter) is also a problem occurs.

And ...
The transistors have been tested properly work only orginal Motorola transistors T
hey did not want to operate transistors: PHILIPS, National
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: tnt on August 02, 2012, 06:55:48 am
@max-bit: This is really strange. I can feed 5V to my pulse gen without any problem, current is less than 20 mA.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: max-bit on August 02, 2012, 10:09:21 am
It's interesting what's the problem ... with the coil?
Used this model:
http://uk.farnell.com/wurth-elektronik/7447779215/choke-smd-150uh/dp/1635996?Ntt=1635996 (http://uk.farnell.com/wurth-elektronik/7447779215/choke-smd-150uh/dp/1635996?Ntt=1635996)
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: DRT on August 02, 2012, 11:10:42 am
I built one of these pulse generators using a BSX20 which seems to work very nicely - I checked it out on a Rohde & Schwarz RTO (2GHz BW 10GS/s) at work which measured a 270ps rise time.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: max-bit on August 02, 2012, 11:40:59 am
Today,  solder the second PCB ....
 We'll see if the problem persists ?
 Can someone this problem occurred?
And this BCX20 what manufacturer?
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: DRT on August 02, 2012, 01:07:31 pm
And this BCX20 what manufacturer?

The BSX20 I used was made by ST.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: max-bit on August 02, 2012, 03:15:44 pm
Case explained. Stupid mistake, capacitor C1, the reverse (polarization!) Soldered (tantalum). ..... always have to double check.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: max-bit on August 02, 2012, 09:57:25 pm
Here are my measurements (unfortunately, not so fast oscilloscopes)
 Oscilloscope OWON SDS8202 - 200MHz 2GS/s
 BW Measurement of rise time of ~ 1.3 nS That is: BW = 0.35 / tr BW ~ = 270 MHz
 And another interesting measurement - TDR (Time Domain Reflectometry)
 Coaxial line to the antenna.
The first reflection after approximately 18 ns / 2 (divide by two because it's time to reach the signal and return) - on the connector cable - Transition from BNC to N
 Second, reflections on antenna surge protection at the time 40 ns / 2
 Final reflections from the antenna 86 nS / 2
 Lc (cable length) x-factor reduction (H-1000 cable x = 0.82)
 Lc = tr * C * x
 LC1 = 2.2 m
 LC2 = 4.92 m
 LC3 = 10.5 m
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: KTP on August 02, 2012, 10:15:15 pm
The Owon SDS8202 looks very nice!

I think you need a flat top for a few nanoseconds however.   If you know the exact amplitude the pulse is supposed to be into whatever load you have, then I guess such a short pulse could be used for BW measurements.

For instance, say on a 1Ghz scope this pulse gets to 10V but on a 200mhz scope it only gets to 7V because the scope rise time is longer than 1/2 of the pulse length.  Wouldn't this make the risetime calculation on the 200mhz scope in error?  It seems you kind of need to know where the signal is going to "level out" in order to get the true 10% and 90% points...
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: KTP on August 02, 2012, 11:15:39 pm
I just did an example to try to prove to myself that it does make some difference if you have a flat top vs a short pulse for rise time measurements.

In the first pic I have the best rise time I have been able to get on my MSOX3024A with a 600ps rise time, flat top (20ns long) pulse.  This was measured at 1.59ns meaning a BW of 220mhz.

In the second pic, I took the same tinylogic circuit, but this time just brushed the input across the table, generating a bunch of very fast short pulses with no flat top.  Now my scope measures the rise time at 1.47ns meaning a BW of 238mhz.

Ok, so they aren't *that* far apart...but it is almost 10% off and makes me wonder even how much shorter I could measure if I had a circuit capable of 200ps rise time.  I think you need the flat top.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: max-bit on August 03, 2012, 10:14:28 am
OWON is not bad, especially as the price taken into account (approximately $ 800)
2GS (for the record 10k) 1GS (over 10k), but here to 10M!
 A little clunky, but something like Agilent, Tektronix is a price above $ 5000
 So do not complain about If the Chinese improved by housing (quality) components, and software.
 It's even a 1300 - 1400 USD was by this revelation.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: T4P on August 03, 2012, 11:50:11 am
Unfortunately 1GS onwards only has 10k memory length
That said if i want a 2GS scope i would go for a Rigol 4000 for 4ch/s or the 2000
But it looks like rigolna is having a problem with their site now
But it's actually onpar with DS1202CA above 1GS (and cheaper)
Can't say the same for the software .. yeah the scope is good and i love the SDS7102 but i'm not sure if the 8202 would be a good buy ... just for the sake of the software if i want a 2GS scope i better be getting me money's worth
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: max-bit on August 03, 2012, 12:25:32 pm
Find cheaper oscilloscope from SDS8202? With these parameters! Rigol is not bad, but the price of x2
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: T4P on August 03, 2012, 04:54:17 pm
Find cheaper oscilloscope from SDS8202? With these parameters! Rigol is not bad, but the price of x2

Sure it is, but 14MB of memory. Why not?
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: max-bit on August 03, 2012, 09:08:21 pm
Model and Price :)
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: T4P on August 04, 2012, 02:16:16 am
Model and Price :)

DS2202  :) And plus it's upgradeable to 56Mpts ...
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: max-bit on August 04, 2012, 04:49:05 am
Compare: Rigol DS1302 Memory 300MHz BW 2 GS 10k only - price 1100 Euro (1375 $)
 Rigol DS2202 14M Memory 200MHz BW 2 GS price 1300 Euro (1645 $) + 300 Euros ($ 360) Total 1600 Euro (2000 $)
and
DS8202 OWON price 650 Euros ($ 825)

 It is a price higher than 2 x ....
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: max-bit on August 04, 2012, 10:46:41 am
Although RIGOL, replanted .... These 54 MB built-in oscilloscope, it is only activated? They were able to sell immediately with 54 MB, and not even take it for a $ 350
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: T4P on August 04, 2012, 05:00:14 pm
Hmm ... where's your 300 euros coming from?
I do not mind paying extra for good software, the owon SDS7102 is a good scope the software is just adequate (i like it ... but i face it, it's not gold) but i won't say the same for the SDS8102
Plus the DS2202 has quite high a acquisition rate (refresh rate or acquisition?)
and 14M ... fullspeed i think
Can somebody confirm?
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: IvoS on August 08, 2012, 09:43:55 pm
Can someone tell me where to get 2N2369 transistor that avalanche? I got some 2N2369A from Mouser and they don't work. :(
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: carpin on August 08, 2012, 09:53:40 pm
Try ebay
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: FRT on August 28, 2012, 09:40:53 pm
Ok, so they aren't *that* far apart...but it is almost 10% off and makes me wonder even how much shorter I could measure if I had a circuit capable of 200ps rise time.  I think you need the flat top.

I totally agree, it does need the flat top, not only so the scope can catch up (because a slow scope with a fast edge won't get to the high logic level fast enough to really know where 10/90 or even 20/80 is) but also so you can see how much overshoot and ringing is created by digital brick wall filtering.   A short pulse will mask this behaviour.

I'd like to get a pulse generator that has a fast edge, but a longer pulse width so the scopes behaviour and settling can be seen.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: G7PSK on September 04, 2012, 08:32:32 pm
Saw this on ebay today.

http://www.ebay.co.uk/itm/390440463608?_trksid=p5197.c0.m619#ht_4348wt_1322 (http://www.ebay.co.uk/itm/390440463608?_trksid=p5197.c0.m619#ht_4348wt_1322)


Pulse generator from type 42 Destroyer.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: prenato on September 19, 2012, 04:58:35 pm
Hi Free-electron

Are you still selling these on ebay? I would definitely be interested...

Thanks,

Paulo
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: free_electron on September 19, 2012, 07:20:19 pm
i'm back from vacation. will prepare the kits over the weekend and throw them on ebay.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: free_electron on October 10, 2012, 01:21:46 am
Finally got some time to finish mine and 'hand select' the transistors for the kits. ( i ran them on the curve tracer and selected the ones that avalanched at around 40 volts. there is notable difference between the 2N2369 and 2N2369A and then manufacturers...
the ones from ST avalanche much higher .... i found a bunc of motoroils at the local junk dealer. these work fine.

Ran the pulser into a 7GHz analog bandwidth scope ( see attached image )

210 pS rise time on an almost 10 Vpp signal ( 10% to 90% ) so 210pS to do 8 volts. That's a -VERY- fast signal. And it may be thelimit of the scope .. (7GHz analog bandwidth ,injected diectly into the 50 ohm SMA port ( this scope has SMA inputs ))

So , i will assemble and package kits today and tomorrow and then they will appear on ebay. i will call the item JWPULSER so search for that starting Thursday. I only charge the cost of the parts. Comes with a case , SMA connector ( no sma-bnc adaptor ) and you get two of the transistors.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: HackedFridgeMagnet on October 10, 2012, 03:53:57 am
Well done!

Looking forward to getting one, hope I'm fast enough.

Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: notsob on October 10, 2012, 05:01:30 am
I put my name in for one when you 1st started - so I'll be looking for one also

Great work
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: prenato on October 11, 2012, 05:22:36 am
Great job! Keeping an eye on eBay now... :)
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: free_electron on October 11, 2012, 05:00:55 pm
i will post them tonight (US - west coast time )
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: robrenz on October 11, 2012, 05:50:15 pm
I already hit the Ebay search button 500 times since your previous post  ;D
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: free_electron on October 12, 2012, 04:40:59 am
and rob_renz takes the crown :)
i'll throw in that low noise cable i promised you. it's been laying in my care ofr 3 months now... just need to get to the darn post office. :)
kits will ship on monday ( if paid ).

Right now there is 5 on ebay ( minus one ).
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: robrenz on October 12, 2012, 04:52:41 am
Thanks free_electron,  I used the JWPULSER search term and it worked and I payed.  but if I go back and search that now it does not find it.  You might want to make sure the listing is still good.  I think it was listed as a single item not multiple.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: free_electron on October 12, 2012, 05:45:01 am
I got the payment. I'll ship yours tomorrow. There's a surprise in there as well. you'll see :p

hmm strange. i see them as 'listed' but ebay search doesnt find them. this whole ebay thing is weird to me. i can never figure it out. just finding how to add international shipping took me an hour.

here are the other 4 listings :

-gone-

http://www.ebay.com/itm/150922538076?ssPageName=STRK:MESELX:IT&_trksid=p3984.m1555.l2649 (http://www.ebay.com/itm/150922538076?ssPageName=STRK:MESELX:IT&_trksid=p3984.m1555.l2649)

http://www.ebay.com/itm/150922538184?ssPageName=STRK:MESELX:IT&_trksid=p3984.m1555.l2649 (http://www.ebay.com/itm/150922538184?ssPageName=STRK:MESELX:IT&_trksid=p3984.m1555.l2649)

-gone-

I will list 2 more tomorrow. after that i am out of boards ...

I can always do another run at itead. But then we need to organize it more so i can buy larger quantity and get price down.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: HackedFridgeMagnet on October 12, 2012, 05:49:41 am
I cant find them, are they gone?
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: notsob on October 12, 2012, 05:49:54 am
I havent been able to get a result for jwpulser search
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: free_electron on October 12, 2012, 05:51:20 am
use th elinks above. for some reason ebay search doesnt find them... the direct links take you there.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: notsob on October 12, 2012, 05:55:09 am
Thank you fe appreciate your efforts
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: free_electron on October 12, 2012, 05:57:25 am
notsob and hackedfridgemagnet payment received. those will leave tomorrow as well :)
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: carpin on October 12, 2012, 07:30:04 am

I can always do another run at itead. But then we need to organize it more so i can buy larger quantity and get price down.
I was sleeping :)

It would be great if you organize a groupsbuy, and the siliconvalleygarage JWpulser as a kit.
And is a BNC male bulkhead connector possible?

Thanks



Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: HackedFridgeMagnet on October 12, 2012, 07:41:10 am
there is one still left carpin, 3rd down
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: carpin on October 12, 2012, 07:51:45 am
Thanks HackedFridgeMagnet
The 3rd down is a auction, Time left:  2d 20h
If I bid on the jwpulser, I always lose :)
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: HackedFridgeMagnet on October 12, 2012, 08:08:50 am
What happens if you press buy it now?
That's what I did.

Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: carpin on October 12, 2012, 08:21:03 am
Thanks again HackedFridgeMagnet
I didn't see the buy it now option.

free_electron can you sign my board with your signature?

Thanks
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: free_electron on October 12, 2012, 07:50:04 pm
off to the post office. they leave in an hour ...
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: robrenz on October 12, 2012, 07:59:27 pm
Thanks free_electron,  I cant wait to test the limits of this thing on my rigol 1052E ::)
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: prenato on October 15, 2012, 12:18:54 am
Missed this, bummer:( The eBay jwpulser searc yielded nothing and by the time I saw the links here they were gone. Free_electron: any chance you'll be selling more? This seems like a runaway hit judging by how fast they sold:)
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: free_electron on October 15, 2012, 04:46:51 pm
i got material for two more. will post on ebay tonight.

if any more people are interested we need to make a list . ican then order parts in bulk.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: robrenz on October 15, 2012, 05:58:50 pm
Mine showed up in todays mail  :).  Thanks free_electron for the cable and the suprise  :P
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: free_electron on October 16, 2012, 02:12:37 am
i'll post some assembly details in the coming days. everyithing is pretty straightforward. i already posted a 3d drawing in this topic on how to mount the transsitor

the easiest way is to solder the 2pf and 10k base resistor first.
then solder the 50 ohm on its side ( it stands up with one electrode sticking out in the air. )
then solder the sma connector on sideways.
take the transisotr and drop it in the hole with the legs sticking up .
bend over the base pin , snip off and solder on the pad.
bend over the right pin toward the center pin of the sma. it will lay flat on the 50 ohm resistor and line up neatly with the center of the sma. two dabs of solder make that connection.

the collector pin you can snip off. the collector is internally bonded to the case of the transistor. simply flip the board over and solder the case to the ring on the backside.

take care when installing the battery clip to orient it correctly.

oh, and keep your hands off the pcb when it is on ! i zapped myself a few times.... drop the pcb in the backshell of the  included case. the pcb clamps itself on the mounting posts without needing screws. tolerances are tight .... that's the beauty of working off the STEP files of this case. I imported the Step file in altium , sliced it to create the board contour and the dimensions and positions of the holes are exact.

some of you may have receive one or two extra resistors. i just ejected these from the feeders.

everyone will hav e receive two of the 2pf caps. These are C0G 100 volt types. you can experiment by doublin the cap value.

my pulser with 4pf gives a whopping 12 volt peak pulse into a 50 ohm 7Ghz input. this is probably ot the maximum as the pulse decays before it reaches the plateau. i need to experiment with a bit of hardline to see if i can extend the pulse.

Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: esharmon on October 16, 2012, 03:09:06 pm
I would be very interested in purchasing several of these -- I would like to use them to drive a laser diode for gain switching.  Sign me up for a group buy.

Eric Harmon
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: carpin on October 17, 2012, 08:12:24 pm
I got mine to free electron, thanks.

I want to use the BNC bulkhead connector I have, I need some space for the nut, can I shorten the pcb 2 mm?
Thanks

Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: free_electron on October 17, 2012, 11:22:49 pm
I got mine to free electron, thanks.

I want to use the BNC bulkhead connector I have, I need some space for the nut, can I shorten the pcb 2 mm?
Thanks

probably. just make sure you do not apply mechanical stress to the 50 ohm resistor... i don;t know how you are going to solder that bulkhead connector down mchanically...
i would simply use a sm-bnc convertor.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: notsob on October 24, 2012, 04:30:36 pm
arrived in wednesday's mail, those poor freight pigeons must be worn out.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: notsob on October 28, 2012, 05:52:16 am
FE a correction to your assembly instructions, 2N2369, the collector is connected to the can, you really don't want to snip off the emitter - it's the output.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: free_electron on October 28, 2012, 04:21:58 pm
fixed it.  thanks.

the right pin is the emitter which you bend out as per description.

 the left pin is indeed the COLLECTOR (and not the emitter as i wrote -brainfart-)

 if the transistor is upside down with the base towards you :

Code: [Select]

     _//   
C --(_)-- E
     |
     B

note : drawn with legs sticking UP : so BOTTOM VIEW !
[code]
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: chavotronic on October 28, 2012, 06:05:33 pm
Hi Free Electron, Did you receive my message?

Best Regards,

David :)
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: HackedFridgeMagnet on October 30, 2012, 05:45:59 am
I got my kit last Friday.
But I can't find the assembly instructions, could somebody point them out please.

Anyone got any results?
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: notsob on October 30, 2012, 07:15:56 am
Basic circuit is on page 93 of App Note AN47 - Linear Tech    www.linear.com/docs/4138 (http://www.linear.com/docs/4138)
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: chavotronic on November 01, 2012, 02:41:34 pm
Okay, seems like noone is getting my personal messages. :'(
Anyone has 2 PCBs left for me?

Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: free_electron on November 01, 2012, 03:50:20 pm
Opsie. I have a few boards left. I will do an ebay storm over the weekend. I will send you a personal link. You only need the board ? Or you want the parts too ?
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: chavotronic on November 01, 2012, 04:48:55 pm
2 kits please parts incl. :) :)
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: HackedFridgeMagnet on November 10, 2012, 06:20:59 am
Free_electron Any chance that I could get a copy of the schematic or some assembly instructions?

Conveniently the laws of Edsel Murphy are included in the app note.
I refer to:
Quote
II.7 An important Instruction Manual or Operating Manual will have been discarded by the receiving department.


If I follow the schematic on page 93 of AN47-130 then the following clause will apply:
Quote
IV.32 After an instrument has been fully assembled extra components will be found on the bench.

Has anyone tested theirs yet?





Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: free_electron on November 10, 2012, 05:37:41 pm
will post this today.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: spelunker on December 24, 2012, 12:32:05 am
Hello  free_electron

I am new to this board. Just upgraded my DS1052E TO DS1102E tonight.

Am looking for the pulser you made up kits for.

Am I way too late? Or will you put together another run?

Looking forward.

George
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: branadic on December 24, 2012, 10:57:38 am
There's no need for a pcb, the parts can be directly soldered to a BNC plug. Attached one of my AN47 avalanche pulsers. In such an assembly the parasitic elements are as small as possible and the pulse shape shows less ringing.
In addition the coaxial cable should be of high quality such as Semi Rigid with small dissipation factor.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: HackedFridgeMagnet on January 01, 2013, 05:34:31 am
Hi
Just made up my JWPulser kit, but I can't get it to work.
I'll just go over the details. If anyone has a suggestion.

The 90v generates ok.
the led lights ok.

The collector measures just over 40v +- say half a volt but I can't get a reliable trigger on the jitter.

The emitter measures almost zero (~10mV) and I cant get a reliable trigger on the waveform. It should be spikes at an interval of 5 useconds.

The Base is interesting, see image, it peaks at 0.6v an decays down to 0.1v with an interval of around 6.5 useconds.
On the image, 0v is centred. This is exactly what I was expecting. I was expecting it should turn the transistor on and create the spike.

I think this is sort of avalanching but I am not sure.

With power off:
I measured 50 ohms on the output and 10k on the base and 1meg on the collector.

I have tried both 2N2369 and the behaviour is the same for both.
Also tried 2pF and 4pf, base of 3.3k and 33k.

I am measuring it with my cro lead, HP10017a which is nominally 10x, 1Meg and 8pF. I haven't got an adapter handy.
It picks up the base waveform ok.

Its almost like the emitter is O/C inside the BJT.
I measured the BJT I took out and it measures both Diode drops correctly.

Or maybe my cro has so much capacitance that the spike dissappears, it shows the base waveform though.

My ESD precautions were not perfect, but I was quite careful with the BJTs, put them on last and carefully. No wrist strap but not moving and keeping myself and tools grounded as best I can.

the other thought was that the legs were around the wrong way, but I have checked Free_Electrons images and the datasheets and measured it the connections seem correct.

Also in the photos you can see I haven't snipped of the Collector leg, I did on the first BJT but I wasn't going to do the second until it was all working.

Any ideas, anyone?
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: HackedFridgeMagnet on January 01, 2013, 05:36:05 am
More pics.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: carpin on January 02, 2013, 01:10:23 pm
Here two schematic drawings that I have.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: free_electron on January 02, 2013, 04:27:24 pm
Check soldering of c4. It may be the pictures, but it looks like one pad did not flow...

The bjts are not sensitive to esd.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: Christe4nM on January 02, 2013, 07:06:22 pm
I can always do another run at itead. But then we need to organize it more so i can buy larger quantity and get price down.
Good idea, count me in
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: spelunker on January 02, 2013, 07:16:10 pm
I can always do another run at itead. But then we need to organize it more so i can buy larger quantity and get price down.
Good idea, count me in


Hi,

YES, you may count me in also.

George
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: EV on January 03, 2013, 02:07:39 pm
Hi  free_electron

Are you going to do more these kits and sell them on eBay?
I am interested to buy one.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: free_electron on January 03, 2013, 03:44:49 pm
Right, lets do another run. I will modify the board slightly in two aspects : a slit in the back that allows you to easily solder a stub of 'hardline' ( rigid coax) so people can experiment withe stretching the pulse.

A different power switch. The current one is a bit iffy to stick through the side of the box. I will stick it through the top. Instead. I'll see if i can lasercut the holes for switch and led in the boxes.

If you want kits: post your name and how many. I will leave this open until the 20th of january. After that i collect the count and order boards and parts (iteadstudio and digikey/mouser). Shipping inside us is around 6$ outside about 15. I use the standard flat-rate  small usps box.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: fmaimon on January 03, 2013, 04:34:04 pm
I'm in for 2 kits!
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: EV on January 03, 2013, 04:55:39 pm
@free_electron

I sent an email to you.

2 pcs
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: Neganur on January 03, 2013, 06:26:54 pm
2
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: tymm on January 03, 2013, 07:23:27 pm
I would be in for 2 -- thanks!
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: Christe4nM on January 04, 2013, 10:21:26 am
Yep I'm in: 1 is fine for me
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: BravoV on January 04, 2013, 10:30:26 am
FE, any chance to use BFG541 instead of 2N2369 ?

Its much cheaper (checked thru findchips) and with the same price as single 2N2369, you can supply more than one for the BFG541s in the kit for us to play/select among them and spares as well just in case it went kaput, also its hell a lot faster too (150 ps) and less voltage.  Info HERE (https://www.eevblog.com/forum/blog/eevblog-306-jim-williams-pulse-generator/msg126252/#msg126252)

If you're going with BFG541 , count me in for 1.

PS : Although there might be some extra work for adapting with the new footprint at the pcb.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: TorqueRanger on January 04, 2013, 03:45:44 pm
Right, lets do another run. I will modify the board slightly in two aspects : a slit in the back that allows you to easily solder a stub of 'hardline' ( rigid coax) so people can experiment withe stretching the pulse.

A different power switch. The current one is a bit iffy to stick through the side of the box. I will stick it through the top. Instead. I'll see if i can lasercut the holes for switch and led in the boxes.

If you want kits: post your name and how many. I will leave this open until the 20th of january. After that i collect the count and order boards and parts (iteadstudio and digikey/mouser). Shipping inside us is around 6$ outside about 15. I use the standard flat-rate  small usps box.
What is this going to cost beside the shipping???
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: EV on January 04, 2013, 03:59:49 pm
I don't know, but the old price seems to have been $ 28 on eBay.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: olepr01@gmail.com on January 04, 2013, 07:40:59 pm
1 kit pls  :)
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: free_electron on January 08, 2013, 09:56:53 pm
people who are on the list so far :


Christe4nM 1x
Spelunker 1x
EV 2x
fmaimon 2x
Neganur 2x
Tymm 2x
BravoV 1x with BFG
 olepr01@gmail.com 1x
Wsalden 1x
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: nadona on January 09, 2013, 12:12:40 am
I like to have one, too.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: Barryg41 on January 09, 2013, 12:56:32 am
I will take one also.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: olegjay on January 09, 2013, 01:32:57 am
Please put me in for one.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: Echo88 on January 09, 2013, 11:52:16 am
Id like to have one too, please.  :)
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: casinada on January 11, 2013, 05:42:28 am
+1 :)
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: free_electron on January 11, 2013, 06:24:34 am
I am running this project on another forum where i am active as well. The goal is to bring the price down and benefit both forums. Now, here is a bit more information :

Due to the volume i will do a bulk order of PCB's . This means  you will be able to order just the PCB. Cost is probably going to be around 2 to 3 US$ for the bare pcb + shipping. Since that can be in an envelope shipping anywhere in the world could be like 1.5$ ...
People wanting just the bare board : let me know how many you want : i will add to the PCB column. Two or 3 pcb's in an envelope should work. More would push shipping up a few dollar.
If you wan tsome extra blank pcb they can be added to the kit for just the cost of the board. the shipping box for the kit is large enough and it has no impact on the price.

CAL option . This is a CALIBRATED version. I charge 5$ for this privilege . What i do is build the Pulse section. I install the 10 meg , 10k 2pf , 50 ohm , transistor and sma connector. Verify the system does generate correct pulses and i make a screenshot from the pulse of YOUR unit. You get the screenshot in electronic format by email. The measurement will be done using a very fast scope. I will post the scope model number tomorrow. i need to look it up. It's got 20Ghz analog bandwidth ( i believe) . So you need to solder the entire switcher section.
*** THE 5$ CAL FEE FROM ORDERS ON THIS FORUM WILL BE DONATED TO THE SAGAN FUND ***

Due to the combined action i can shave off a few dollars. I will post a final price end of next week ( when the order time closes ) . Due to chinese new year coming i need to order then.
Any excess money due to penny pinching will be donated to the 'Sagan fund' as well.

( note only the 5$ from EEvblog users goes to the Sagan fund. The Cal fee from the other forum goes to the other forum to pay their bandwidth ( they are a free forum also) . Trying to keep things fair. )

people who are on the list so far :

Code: [Select]
                  Kit   : CAL  :  PCB
Christe4nM         1x   :      :
Spelunker          1x   :      :
EV                 2x   :      :
fmaimon            2x   :      :
Neganur            2x   :      :
Tymm               2x   :      :
BravoV             1x   :      :           with BFG
olepr01@gmail.com  1x   :      :
Wsalden            1x   :      :
nadona             1x   :      :
Barryg41           1x   :      :
olegjay            1x   :      :
echo88             1x   :      :
casinada           1x   :      :

so let me know what features you want so i can finetune the table above.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: BravoV on January 11, 2013, 06:44:48 am
Geez.. why I'm the one who only want BFG ?  ??? Also is there any plan to adapt the pcb for the BFG's footprint ?

Vincent, on every kit, does it came with "more than" one transistors ? I'm worry only one is not enough, whats you plan on how many you're going to purchase on this BFG ?

Btw, I can't lurk here all the time waiting for your announcement at ebay, cause prolly I might missed the bidding. Don't have any problem at all paying you in directly in advance on CAL'ed version, please PM me your paypal addie.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: EV on January 11, 2013, 07:34:27 am
I take also the kits as calibrated. I can also pay directly in advance to you, if you mail your paypal address to me.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: andyturk on January 11, 2013, 07:40:19 am
Put me down for one calibrated kit please.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: free_electron on January 11, 2013, 07:56:31 am
I will accept paypal directly. No problemo.
The pcb will not be adapted to the bfg footprint. Simply solder the tab of the bfg in the hole of the 2n, use one of the emitters to inject into the sma and use a short piece of bare copper to tack down the base.

The transistor needs to be floating to guarantee as fast a pulse as possible. I looked at the pinout of the bfg so you can solder it like that without problems.

For the bfg i was going to get you as a courtesy. Two or three. I will not test those as it is not the jw design. Anyone is free to play with any transistor he wants. The board is made for the 2n2369. The kit will have two of those and i will test both to see if they avalanche around 40 to 60 volts.
 I cannot start buiding custom kits for everyone. Is you want to play with crazy things : get a few bare boards.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: BravoV on January 11, 2013, 08:09:46 am
Thank you Sir !  :-+ Check your PM please.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: Scuba on January 11, 2013, 10:40:59 am
Hello,

Please sign me up with 1 calibrated kit and 1 non-calibrated kit. Thank you!
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: nadona on January 11, 2013, 10:44:14 am
yes, one calibrated kit, please.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: Echo88 on January 11, 2013, 10:54:05 am
One calibrated kit please  :)
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: HackedFridgeMagnet on January 11, 2013, 11:41:34 am
Sagans going to be rich!
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: Christe4nM on January 11, 2013, 12:30:23 pm
 :-+ In that case I'd like to change my previous selection into "1 calibrated kit + 1 bare pcb"
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: fmaimon on January 11, 2013, 12:59:47 pm
I would like one of my boards calibrated. The other will be delivered as a kit, not assembled, right? How much would it cost to also include two BFGs for me?
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: gibbled on January 11, 2013, 06:39:08 pm
Please mark me down for one kit and one extra PCB.


Thanks,
James.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: Neganur on January 12, 2013, 06:28:51 am
both calibrated, cheers!
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: AlfBaz on January 12, 2013, 07:01:33 am
Thank you very much for this...
I'll have 2 cal'd kits and 3 PCB's

I'm assuming info on how to pay you and where to send email and shipping addresses will be forthcoming?
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: Teneyes on January 12, 2013, 11:02:29 am
Phew, just started reading this Forum, good education, 

Put me down for one calibrated kit please.   Paypal, USA
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: free_electron on January 12, 2013, 10:50:37 pm
Action will close Jan 19. I will order the PCB's then so we get them before chinese new year. There will be plenty of PCB's so if anyone wants a bare board later : no problem , they go in an envelope

I am at well over 50 kits now for EEvblog and CircuitsOnline combined (Circuitsonline is a dutch language forum about electronics i have been active on since ..i can't remember . Started when i was still living in belgium. must have been early 2005 or so. I hit 15000 posts there last year.. )

I found a bunch of the original 2n2369 made by SGS in the gold lead packages so not the cheapo motoroil version.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: marshallh on January 17, 2013, 06:25:08 pm
I'm down for one kit, calibrated
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: blackknife on January 17, 2013, 06:51:16 pm
How much for a complete kit incl. shipping to italy?
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: free_electron on January 17, 2013, 08:27:11 pm
shipping internationally is always around 16$.
the kit price will come down as we are approaching a large volume now . i sold them in the past for 28$ but it is most likely going to be around 20$ now ...

this is a combined action running on another forum. the total count sits over 60 kits ... and i have not update what happened this week. its probably closer to 80 kits now ..
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: enz on January 18, 2013, 09:08:18 am
I'm also down for one calibrated kit.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: G7PSK on January 18, 2013, 02:19:19 pm
Another kit here please. Thank you. How will you let us know what your pay pal address is.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: BravoV on January 18, 2013, 08:10:18 pm
Hope not too late for last minute change, 1 kit with calibrated option + 1 plain kit, this will be the host for the BFG, really, dunno why I missed it.  :palm:
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: robrenz on January 18, 2013, 08:21:47 pm
1 calibrated kit please.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: Noize on January 18, 2013, 09:17:42 pm
1 calibrated kit please. UK Paypal
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: sdscotto on January 19, 2013, 04:25:09 am
I PM'd two calibrated and one PCB a couple of days ago, but wanted to make sure just in case you don't check PM.

Thanks!
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: free_electron on January 19, 2013, 04:56:13 am
I saw the pm. Don't worry. I'll post a summary list update tomorrow.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: cyr on January 19, 2013, 07:54:26 am
One calibrated kit for me as well please, assuming I'm not too late.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: free_electron on January 19, 2013, 05:36:11 pm
This is the list as it is now. The action Closes tomorrow Jan 20 at 8PM Pacific time (California time)

Code: [Select]
                  Kit   : CAL  :  PCB
alfbaz                  :  2x  :  3x
andyturk                :  1x  :
Barryg41           1x   :      :
BravoV             1x   :  1x  :           with BFG
casinada           1x   :      :
Christe4nM         1x   :      :  1x
cyr                     :  1x  :
echo88             1x   :  1x  :
enz                     :  1x  :
EV                      :  2x  :
fmaimon            1x   :  1x  :
g7psk                   :  1x  :
giibbled           1x   :      :  1x
marhall_h               :  1x  :
nadona                  :  1x  :
Neganur                 :  2x  :
noize                   :  1x  :
olegjay            1x   :      :
olepr01@gmail.com  1x   :      :
robrenz                 :  1x  :
sdscotto                :  2x  :  1x
Spelunker          1x   :      :
suba               1x   :  1x  :
teneyes                 :  1x  :
Tymm               2x   :      :
Wsalden            1x   :      :

------------------------------------
                  14x   : 21x  :  6x

I will do a bulk order of boards so there will be extra's. So don't despair if you missed the boat. there is wiggle room.(probably ill have 20 or so extra boards.)

You can still change your  mind on the CAL option for another 2 weeks ( it takes 10 working days to get the bare boards )

The Kit parts will be ordered Jan 28 So they arrive together with the boards. So also there you have some time.
I will post a preliminary price calculation in a moment, i need to collect the tally from the other forum as well.

Looks like Sagan's got at least 105 AU$ coming his way ...

Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: Christe4nM on January 19, 2013, 06:26:06 pm
Hi free_electron, Could I have my kit w/ cal option please? Sagan would be happy ;)
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: free_electron on January 19, 2013, 07:17:47 pm
will do.

Final pricing :
Code: [Select]
Kit (all parts , case , pcb)                : 22   US$
Calibration Option                          : 5    US$
Bare Board                                  : 2    US$

Shipping :
Inside US                                   : 5.35 US$ 
International Shipping                      : 17   US$
Bare Board ship (international): 4$

If you ordered multiple items : they fit together in 1 box ( up to 3 pounds ... these things are light enoug it all fits. )
Payment through Paypal directly form your bankaccount or debet card. I already took into account the small transaction fee PP charges. If you pay with CREDIT card through paypal you need to add 2$ ..

Example : 1 kit + 1 cal kit + 1 bare board , international shipping

[22 U$(kit)] + [22 us$(kit) + 5US$(cal)] + [2 US$] + [17 US$]  = 68 US$

I will declare actual value to customs. ( USPS insures the package for the declared value. So if it gets lost at least i don't lose the money.)  Prce is low enough that there should be no local import duty ... If there is : It's your responsability

Does anyone know the ITAR code for such things ? It is easier if it fits under a known ITAR code.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: komet on January 19, 2013, 08:37:42 pm
I should like to get a calibrated kit as well, please.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: plesa on January 19, 2013, 09:35:57 pm
One kit and one bare PCB for me ( I send also PM  )
The ITAR code can be 8543200000
Thanks
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: olegjay on January 20, 2013, 09:45:59 pm
Hi free_electron; Please finalize me for "2 calibrated" and "2 bare boards".  (You had me for 1 kit on your Jan 11 posting and you didn't have me at all on your Jan 19 posting.)
That would be a total of 2x$22 + 2x$5 + 2x$2 + $2(credit card to paypal) + $5.35 = $65.35. Is this the price directly or through ebay?
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: grenert on January 20, 2013, 10:03:22 pm
Wow, thanks for making this available again!  The calibration option alone is worth the price of the whole thing, I think.
Please put me down for one calibrated kit and one bare PCB.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: casinada on January 22, 2013, 06:46:47 am
Free_Electron,
Can you change mine from Kit to Calibrated?.
Thank you
Daniel (casinada)
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: nadona on January 24, 2013, 03:37:02 am
I like mine calibrated. Thank you very much.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: free_electron on January 24, 2013, 03:16:26 pm
Keep posting. I'll update the table over the weekend. I placed the order yesterday for the parts from digikey. That put a dent in my creditcard :). I should have parts friday. Pcb's will be ordered saturday. I changed the switch so it sticks through the front panel. Since i have never used that particular switch i hold off sending the board for fab.. I have an'unbreakable' rule : if using a part footprint for the first time i need the physical part in hand....

I have the transistors already and will test them for avalanching this weekend. Pcbs should be in around feb 4. After which kits will start leaving.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: Circuitous on January 24, 2013, 03:39:37 pm
Sign me up for a calibrated one!

Sent from my SPH-D710 using Tapatalk 2

Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: Scuba on January 24, 2013, 04:21:37 pm
That put a dent in my creditcard :).

Well, then please let us know your Paypal account ;) . (PM?)
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: biot on January 24, 2013, 06:45:51 pm
Keep posting. I'll update the table over the weekend.

I tried to IM you, but I think it may have mailed instead. In any case, please sign me up for a calibrated version with international shipping.

Thanks!
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: BravoV on January 25, 2013, 01:40:35 am
Pcbs should be in around feb 4. After which kits will start leaving.
Vincent,
I'm sitting nicely here waiting for you to get prepared, please announce the procedure in details like paypal payment, payment confirmation and shipping address details, so you wont get overwhelmed by it. Also I mentioned earlier, I will paypal you directly bypassing ebay once you're ready.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: free_electron on January 25, 2013, 05:28:02 am
don't worry about payments yet guys. i need to set up a few things so this does not end up being a logistics mess.
Wait until after the weekend. my credit card can take larger 'dents' than that :)
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: free_electron on January 27, 2013, 10:29:00 pm
Jim Williams PulseGenerator MK-II

Top view
(http://www.siliconvalleygarage.com/eevblog/pulsegen/PGMK2.png)


Bottom View
(http://www.siliconvalleygarage.com/eevblog/pulsegen/PGMK2B.png)

i rearranged the components to have as large a ground mass a possible for the waveguide.
I 'stole' the idea from this topic :

https://www.eevblog.com/forum/projects/transmission-line-avalanche-pulse-generator/msg185694/#msg185694 (https://www.eevblog.com/forum/projects/transmission-line-avalanche-pulse-generator/msg185694/#msg185694)

The waveguide is 750 degrees long and 50 ohms. 25 mil track in an 8 mil gap

You can either use it or not. By installing the 1 meg resistor on top you use the 'MK-I style.
By installing R1A on the bottom and closing the solderbridge next to the transistors hull you use MK-II style

Boards will be ordered tomorrow at ITeadStudio.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: EV on January 27, 2013, 10:54:02 pm
Jim Williams PulseGenerator MK-II

You can either use it or not. By installing the 1 meg resistor on top you use the 'MK-I style.
By installing R1A on the bottom and closing the solderbridge next to the transistors hull you use MK-II style

I have ordered 2 pcs calibrated. Can you make one with MK-I style and the other with MK-II style? Thanks!
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: AlfBaz on January 28, 2013, 12:32:29 am
I presume they will all be MKII. You choose if you want to use the built in delay line (MKII) or not (MKI).
Thank you free_electron for the mod and thank you Jay_Diddy_B for the idea
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: nadona on January 29, 2013, 06:45:26 am

First Class Design as I expected! ;D

Jim Williams PulseGenerator MK-II

Top view
(http://www.siliconvalleygarage.com/eevblog/pulsegen/PGMK2.png)


Bottom View
(http://www.siliconvalleygarage.com/eevblog/pulsegen/PGMK2B.png)

i rearranged the components to have as large a ground mass a possible for the waveguide.
I 'stole' the idea from this topic :

https://www.eevblog.com/forum/projects/transmission-line-avalanche-pulse-generator/msg185694/#msg185694 (https://www.eevblog.com/forum/projects/transmission-line-avalanche-pulse-generator/msg185694/#msg185694)

The waveguide is 750 degrees long and 50 ohms. 25 mil track in an 8 mil gap

You can either use it or not. By installing the 1 meg resistor on top you use the 'MK-I style.
By installing R1A on the bottom and closing the solderbridge next to the transistors hull you use MK-II style

Boards will be ordered tomorrow at ITeadStudio.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: fmaimon on February 08, 2013, 09:43:48 pm
Vincent,

What's your paypal, so we can send the payment for the kits?
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: free_electron on February 13, 2013, 09:44:45 pm
they just arrived !

guess i'll be building over the weekend :)
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: sdscotto on February 14, 2013, 12:56:51 am
Great!   Is this designed for any available case?
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: Orpheus on February 14, 2013, 03:24:56 am
Is it too soon to get in line for any uncalibrated leftovers?
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: G7PSK on February 14, 2013, 11:35:42 am
How are you going to notify us of your paypal address PM or published on here.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: free_electron on February 14, 2013, 02:13:56 pm
Yep, this is specifically designed for a particular case using the 3d STEP model of that case.
I have spare kits, no problem.

For payment:

Payment is through paypal. My paypal accou t is my email address ( found in my profile )
In the comment section clearly state:

The shipping address includong the country
What you need

For example 1xkit , 2xcal, 1x board.

To make it clear

KIT. Means all parts,pcb and case.
CAL means a KIT that is semi-built and has a been measured on a high performance scope. A scope plot with rise time will be provided. The cal fee is donated to Dave's Sagan fund.
PCB means the bare board.

Add the costs up and add the shipping fee.
I have posted the numbers before.

Each kit comes with a spare transistor. These are gold legged hi end transistors , not the cheapo tin plated ones.
I will start building this weekend . People who buy just the kit will be serviced first . Cal'd kits will probably start leaving around the 25th of february as i need to arrange the hi end scope.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: marshallh on February 14, 2013, 03:07:50 pm
Love to send you money but this forum doesn't show your email address  :-/O
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: free_electron on February 14, 2013, 03:16:53 pm
Oh darn, you're right.... I always assumed since it showed mine when i clicked on my handle it did that for everyone. Drat.

Hmmm. Don't really want to throw that out in the open.. I'll send people a message through the forum
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: andyturk on February 14, 2013, 03:22:51 pm
Checking the numbers...

I ordered one 1x CAL. I think that comes to:

1x kit                  $22
CAL                     $5
Shipping (US)      $6
---------------------------
                           $33

Correct?
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: free_electron on February 14, 2013, 03:24:50 pm
Looks right to me.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: G7PSK on February 14, 2013, 03:28:42 pm
I make it 44$ for the UK  22$ X1 Kit
                                        05$ Cal.
                                         17$ International post.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: free_electron on February 14, 2013, 04:22:14 pm
The 'LIST' -updated FEB15 8AM PST-

Sagan's fund is already at 20 125 US$

This will be updated with more info as we go.

current status :

- if you're not on the list or have not received the PM: post below or send me a PM ASAP so i can add you and send instructions

- When i get the paypal information in i will update your line with the exact mixture you ordered ( don't worry if it is wrong right now , we go by the paypal order.) and the text -PAID- will appear behind the PM mark. At that point your order is sealed. Doublecheck i got the right mix, or you didn't mess up (like EV.. ordering 2xkit but paying for 2xcal  ;D) i am human... albeit slightly.

***WINNER*** G7PSK was the first to pay.

- as soon as your box is handed off to USPS the text -SHIPPED- will appear as well.

I have spare kits and boards so if you want to 'up' you can do so during the paypal transaction. i will update the table accordingly.

The jazz is on (as hannibal used to say)


                   Kit   : CAL  :  PCB: PM : PAID : SHIPPED
alfbaz                  :  2x  :  3x : pm : PAID :
andyturk                :  1x  :     : pm : PAID :
Barryg41                :  1x  :     : PM : PAID :
biot                    :  1x  :     : PM : PAID :
BravoV             1x   :  1x  :     : PM : PAID :     with BFG
blackknife         1x   :      :     : pm :      :
casinada                :  1x  :     : pm : PAID :
circuitous              :  1x  :     : pm : PAID :
Christe4nM              :  1x  :  1x : pm : PAID :
condor                  :  1x  :     : pm : PAID :
cyr                     :  1x  :     : pm : PAID :
echo88             1x   :  1x  :     : pm :      :
enz                     :  1x  :     : pm : PAID :
EV                      :  2x  :     : pm : PAID :
fmaimon            1x   :  1x  :     : pm : PAID :       bfg
g7psk                   :  1x  :     : PM : PAID :
gibbled            1x   :      :  1x : pm : PAID :
grenert                 :      :     : pm :      :
komet                                : PM :      :
marshallh               :  1x  :     : pm : PAID :
nadona                  :  1x  :     : pm : PAID :
Neganur                 :  2x  :     : pm : PAID :
noize                   :  1x  :     : PM :      :
olegjay                 :  2x  :  2x : pm : PAID :
olepr01@gmail.com  1x   :      :     : pm :      :
plesa              1x   :      :  1x : pm :      :
robrenz                 :  1x  :     : pm :      :
sdscotto                :  2x  :  1x : pm :      :
Spelunker          1x   :      :     : pm :      :
suba               1x   :  1x  :     : PM :      :
teneyes            1x   :  1x  :     : pm : PAID :
Tymm                    :  2x  : 1x  : pm : PAID :
Wsalden            1x   :      :     : pm :      :

------------------------------------
                  11x   : 31x  :  10x
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: EV on February 14, 2013, 06:00:11 pm
I'll send people a message through the forum

OK, I am waiting your message!
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: olegjay on February 14, 2013, 06:29:09 pm
Hi free_electron,

You have me down in your list for a total of just 1 kit (as per my initial request sent 1/19/2013 msg).  But I modified my request on my 1/20/2013 msg (Reply #204) to a total of "2 Calibrated and 2 bareboards".  Can I pay and get the final request (2 calib & 2 bare)?
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: free_electron on February 14, 2013, 06:41:00 pm
jep. no problem. i have spares.

Like is said : if you want a different mix simply pay what you want . i will update the table above based ont he paypal transaction. i have extra boards and parts so it's no problem.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: BravoV on February 16, 2013, 12:34:09 am
Hey Vincent, just curios what scope you're planning to use to generate the plot for CAL unit ?

Also want to say I really appreciate this really nice extra service you provided, thank you.  :-+


Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: free_electron on February 16, 2013, 01:00:15 am
The stuff dreams is made off : a 33GHz bandwidth, 80Gs/s DSA-X93204A courtesy of Agilent. I called in a favor...

-WARNING-  If you go look that model up make sure you sit down before your eyes wander to the right of the screen where the price is stated ... this is beyond eye-watering territory. Many people live in houses that are cheaper than that...

That should state beyond a figment of doubt what the pulser really does as rise time , and, that whatever pulse you see on YOUR scope when you attach the pulse generator is caused by the bandwidth limitation of your scope.

Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: BravoV on February 16, 2013, 01:16:40 am
Damn, I drolled big time just seeing the spec ...  :phew:

- 80 GSa/s sample rate
- 50 Mpts per channel
- noise floor 2.15 mVrms at 33 GHz at 50mV/div
- jitter measurement floor <100 fS  :o

Now, you've made my patience nerve shrink thinner, just can't wait to receive mine.  :-+
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: free_electron on February 17, 2013, 01:50:29 am
Success !. i just built prototype 1. fully working. the stripline also works nicely. i get a 5ns pulse with a very sharp rise time.
screencaptures below

first picture is the built assembly
second picture in the regular version
thrid picture using the backside stripline. this gives a 5nS pulse.

Note : this is measured using my older 600MHz Infiniium 54831A.  So that rise time is way faster. I am going to assemble all of them using the stripline.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: BravoV on February 17, 2013, 02:19:43 am
Glad to see the new revision with the stripline works, great news !  :-+
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: casinada on February 17, 2013, 05:36:53 am
Are you using more than one adapter to connect the pulser to the scope?
BNC-M - SMA-F to SMA-M - SMA-M to Pulser ?
Thank you
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: BravoV on February 17, 2013, 06:58:46 am
Are you using more than one adapter to connect the pulser to the scope?
BNC-M - SMA-F to SMA-M - SMA-M to Pulser ?
Thank you
I believe using sma male to bnc male is enough.

(http://www.rfsolutions.co.uk/acatalog/ADP-SMAM-BNCM-500.gif)
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: free_electron on February 17, 2013, 03:40:48 pm
I didn't have the right one laying around... (I know i have some, couldn't find them).  Oh, and i also forgot to put the scope in 50 ohm.... I took new pictures with the scope in 50 ohm mode and the ringing at the top is almost gone. There is still a 'step' at the tail. But you get a nice 5ns pulse with razorsharp risetime. I've built the first 20 and they all work. Today i'm out but i'll post the screencaptures tonight. I'll hook up my 1Ghz machine tonight. I'll try to get rid of the step at the end as well.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: Jay_Diddy_B on February 17, 2013, 03:56:01 pm
Hi,
When you borrow the very expensive Agilent scope, don't forget to use an attenuator. The typical amplitude of the 2N2369A pulser will damage the input which is 5V max.

Jay_Diddy_B

Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: free_electron on February 18, 2013, 06:08:16 am
I'll be using their active probes. Those can handle the pulse.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: notsob on February 18, 2013, 07:27:53 am
Hey Vincent, have you compared the 2N against the BFG version.

Just curious

Peter
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: BravoV on February 18, 2013, 08:19:02 am
Hey Vincent, have you compared the 2N against the BFG version.

Just curious

Peter

<sigh> ... I've been dying just to see how it performs for quite some time now ...  :'(
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: free_electron on February 18, 2013, 04:00:59 pm
I do t have the bfg transistors yet. Need to order them.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: free_electron on February 18, 2013, 05:09:59 pm
Update


                  Kit   : CAL  :  PCB: PM : PAID : SHIPPED
alfbaz                  :  2x  :  3x : pm : PAID :
andyturk                :  1x  :     : pm : PAID :
Barryg41                :  1x  :     : PM : PAID :
biot                    :  1x  :     : PM : PAID :
BravoV             1x   :  1x  :     : PM : PAID :     with BFG
blackknife         1x   :      :     : pm :      :
casinada                :  1x  :     : pm : PAID :
circuitous              :  1x  :     : pm : PAID :
Christe4nM              :  1x  :  1x : pm : PAID :
condor                  :  1x  :     : pm : PAID :
cyr                     :  1x  :     : pm : PAID :
echo88             1x   :  1x  :     : pm : PAID :
enz                     :  1x  :     : pm : PAID :
EV                      :  2x  :     : pm : PAID :
fmaimon            1x   :  1x  :     : pm : PAID :       bfg
g7psk                   :  1x  :     : PM : PAID :
gibbled            1x   :      :  1x : pm : PAID :
grenert                 :  1x  :     : pm : PAID :
komet                   :  1X  :     : PM : PAID :
marshallh               :  1x  :     : pm : PAID :
nadona                  :  1x  :     : pm : PAID :
Neganur                 :  2x  :     : pm : PAID :
noize                   :  1x  :     : PM : paid :
olegjay                 :  2x  :  2x : pm : PAID :
olepr01@gmail.com  1x   :      :     : pm : PAID :
plesa              1x   :      :  1x : pm : PAID :
robrenz                 :  1x  :     : pm : PAID :
sdscotto                :  2x  :  1x : pm :      :
Spelunker          1x   :      :     : pm :      :
sCuba              1x   :  1x  :     : PM : PAID :
teneyes            1x   :  1x  :     : pm : PAID :
Tymm                    :  2x  : 1x  : pm : PAID :
Wsalden            2x   :      :     : pm : PAID :


sagan's fund is at 150$ now.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: free_electron on February 22, 2013, 05:46:46 am
Tomorrow is D-Day

Camera charged, memory erased - check
Memory stick - check
SMA cables Semi rigid 10 Ghz - Check
Box with pre-tested pulsers - check
test jig - check
attenuator - check
agilent t-shirt -check

i will visit the museum as well . i'll post photo's
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: BravoV on February 22, 2013, 06:06:58 am
Sharpie - checked ?  ;)
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: free_electron on February 22, 2013, 06:40:50 am
they are already marked both on the pcb and antistatic bags. i'll scavenge an Agilent pen >:)
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: SeanB on February 22, 2013, 04:28:20 pm
Scavenge a box, and send one with each meter........
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: free_electron on February 22, 2013, 09:39:54 pm
And the results are in! They range from 170pS to 210pS for a 8 vpp pulse measured at 20 to 80% into 50 ohm.

So the JW pulser is faster than Jim ever was able to measure. We are talking in the 30pS per volt range... Given that agilents calibrator does 15...

It's one hell of a scope!

I got closeups of the a/d converter chip....
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: BravoV on February 26, 2013, 02:51:07 am
Stop teasing us, post one of the captured trace please.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: Teneyes on February 26, 2013, 05:02:47 am
@BravoV
  "all good things come to those who wait"
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: BravoV on February 26, 2013, 05:19:58 am
@BravoV
  "all good things come to those who wait"

A ha.... ok..ok.. this one I have to agree.  ;D
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: free_electron on February 26, 2013, 03:39:46 pm
I'm busy assembling packages :). First units will go out the door thursday. I am milling the cases right now.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: BravoV on February 26, 2013, 04:35:30 pm
Since you've played with "unnaturally" huge amount  ;D of 2N2369A transistors lately when preparing the cal kit, just curious, are there any huge variations on the tR between them ? Also the voltage where it starts to avalanche, did you just set it at fixed voltage at all boards, or you tweaked the voltage each of them ?

If there is a Guinness book of record on tweaking amount of 2N2369A for avalanching purpose, I'm guessing you must be the winner.  :-DD  ....j/k

Thanks !  :-+
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: firewalker on February 26, 2013, 04:39:09 pm
I'm busy assembling packages :). First units will go out the door thursday. I am milling the cases right now.

If you sell enough of them you could buy one of those Agilent oscilloscope and test every one individually and send a certificate in the packet!  :P :P :P

Alexander.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: free_electron on February 26, 2013, 09:46:05 pm
i will publish the numerical data of every unit i measured so the math-freaks can 'massage' it a bit.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: jpb on February 28, 2013, 03:33:26 pm
free_electron,

have you any spare boards for late-comers or any plans for a second batch? (I've also clogged up your in-box with a couple of pms - sorry to be annoying!)
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: free_electron on March 04, 2013, 03:12:04 am
Here's an update of stuff that is leaving tomorrow.
if your name has serial numbers or 'shipped' behind your line : those leave monday march 4



                  Kit   : CAL  :  PCB: PM : PAID : SHIPPED
alfbaz                  :  2x  :  3x : pm : PAID :
andyturk                :  1x  :     : pm : PAID : serial 4
Barryg41                :  1x  :     : PM : PAID : serial 5
biot                    :  1x  :     : PM : PAID :
BravoV             1x   :  1x  :     : PM : PAID :     with BFG
blackknife         1x   :      :     : pm :      :
casinada                :  1x  :     : pm : PAID : serial 18
circuitous              :  1x  :     : pm : PAID : serial 17
Christe4nM              :  1x  :  1x : pm : PAID :
condor                  :  1x  :     : pm : PAID : serial 7
cyr                     :  1x  :     : pm : PAID :
echo88             1x   :  1x  :     : pm : PAID :
enz                     :  1x  :     : pm : PAID :
EV                      :  2x  :     : pm : PAID :
fmaimon            1x   :  1x  :     : pm : PAID :       bfg
g7psk                   :  1x  :     : PM : PAID :
gibbled            1x   :      :  1x : pm : PAID :
grenert                 :  1x  :     : pm : PAID : serial 12
komet                   :  1X  :     : PM : PAID :
marshallh               :  1x  :     : pm : PAID : serial 15
nadona                  :  1x  :     : pm : PAID : serial 53
Neganur                 :  2x  :     : pm : PAID :
noize                   :  1x  :     : PM : paid :
olegjay                 :  2x  :  2x : pm : PAID : serial 63 / 16
olepr01@gmail.com  1x   :      :     : pm : PAID :
plesa              1x   :      :  1x : pm : PAID :
robrenz                 :  1x  :     : pm : PAID : serial 9
sdscotto                :  3x  :     : pm : PAID :
Spelunker          1x   :      :     : pm :      :
sCuba              1x   :  1x  :     : PM : PAID :
teneyes            1x   :  1x  :     : pm : PAID : serial 14
Tymm                    :  2x  : 1x  : pm : PAID : serial 46 / 36
Wsalden            2x   :      :     : pm : PAID :

Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: condor on March 07, 2013, 08:23:02 pm
Hi
Got my package (7) today, Thanks.
But where is the assembly drawing or assembly instructions?
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: marshallh on March 07, 2013, 10:22:02 pm
Got the kit. Really nice job.
I gave my best shot at assembly but I"m too chicken to put in the battery until I'm 100% sure

(http://img843.imageshack.us/img843/6824/img0849yr.jpg)
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: HackedFridgeMagnet on March 07, 2013, 10:25:20 pm
AN47 on page 93.

In about the first 10 pages of this thread. there is some discussion.

the things to watch are the bjt pinout and the mounting of the emitter with the 50ohm resistor.

there are some extra small caps and spare positions for them, just put in one to start.

Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: BravoV on March 08, 2013, 04:09:11 am
Got the kit. Really nice job.
I gave my best shot at assembly but I"m too chicken to put in the battery until I'm 100% sure

I thought CAL-ed version came with the avalanche transistor soldered at the board ? or did you solder it your self ?
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: condor on March 08, 2013, 04:21:04 am
The transistor is soldered to the board. So I am lazy, I just didn't want to reverse-engineer the board to see where the rest of components go.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: BravoV on March 08, 2013, 04:24:45 am
The transistor is soldered to the board. So I am lazy, I just didn't want to reverse-engineer the board to see where the rest of components go.

Oh .. ok, so all components are already soldered and ready to use when you received it ?
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: casinada on March 08, 2013, 06:09:48 am
Thank you Vincent, I received the package. Now I have to put it together :)
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: robrenz on March 08, 2013, 12:20:42 pm
Got mine yesterday ;D  9 pico seconds... :scared: Wow Vincent, nice job  :-+  Thanks again.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: condor on March 08, 2013, 01:46:16 pm
BravoV:
Only the transistor is soldered in. Everything else comes loose in poly bags. I was just looking for assembly instructions or a parts list with reference designators.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: EV on March 08, 2013, 02:09:11 pm
How is it calibrated, if it is not assemled?
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: AlfBaz on March 08, 2013, 02:14:54 pm
...CAL means a KIT that is semi-built and has a been measured on a high performance scope. A scope plot with rise time will be provided....
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: condor on March 08, 2013, 02:45:49 pm
As I said, only the transistor, R6, the 50ohm emitter resistor, and C2 are soldered to the board. I did not receive a rise-time plot or any documentation at all..
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: casinada on March 09, 2013, 12:05:16 am
Relevant information about the JW Pulse Generator Rev 2 (Vincent's PCB design)
As soon as I assemble the pulse Generator I will create a list of materials unless somebody else beats me to it.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: condor on March 09, 2013, 02:14:22 am
Thanks a lot Casinada, just what I was hoping for!
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: BravoV on March 09, 2013, 03:28:49 am
Got mine yesterday ;D  9 pico seconds... :scared: Wow Vincent, nice job  :-+  Thanks again.
Wow, have you receive the plot from Vincent ?

casinada & condor, thanks !  :-+

Edit :
Btw, I assumed Vincent applied the same avalanche voltage externally to all CAL kits ?
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: robrenz on March 09, 2013, 03:39:53 am
Wow, have you receive the plot from Vincent ?

Not yet but I am not complaining.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: BravoV on March 09, 2013, 03:43:05 am
robrenz, what did you use to measure that 9 pS ? Thats one hell of a crazy speed there.  :o
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: robrenz on March 09, 2013, 03:48:14 am
robrenz, what did you use to measure that 9 pS ? Thats one hell of a crazy speed there.  :o

I can read 9 picosecond rise time with my bare eyes and no scope needed :bullshit:
(It is printed on the board as the calibrated rise time) ;D
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: BravoV on March 09, 2013, 03:51:39 am
LOL  :-DD , must be on the back side then, cause if you see marshallh's board few posts back, its cal-ed but nothing printed/written in there.  :-//
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: marshallh on March 09, 2013, 05:57:46 am
Your serial number is written in the CAL label. Mine was serial 15 but came off with isopropyl while cleaning.
The serial is used as an index so if/when Vince is able to email out the plots you can use it to tell which was yours.

He's already said what kind of results are likely:
"They range from 170pS to 210pS for a 8 vpp pulse measured at 20 to 80% into 50 ohm."
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: nadona on March 09, 2013, 06:00:14 am

"(It is printed on the board as the calibrated rise time) ;"

Yes, it is the serial number. My number is 53ns. Slower than my Hantek DSO;D 

Thank you Vincent for the amazing work.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: marshallh on March 09, 2013, 06:40:43 am
330ps fully saturating the input of my 1ghz scope (that is 0.35 / 0.33 = 1.09ghz)

(http://img600.imageshack.us/img600/5986/d028.png)

And I had to try the 100mhz tek... no comparison lol

(http://img7.imageshack.us/img7/1499/img0855gwk.jpg) (this is through a 50ohm terminator)

EDIT: dug up the tek 464

(http://img14.imageshack.us/img14/7817/img0857iz.jpg)
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: BravoV on March 09, 2013, 07:11:06 am
Nice plots marshallh, thank you !  :-+
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: free_electron on March 09, 2013, 06:15:00 pm
i will post assembly instructions and the calibration data today. been busy assembling boxes and writing customs paperwork :)

the number written on the PCB is the serial number. don't worry if it came off with alcohol, i know who got what.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: free_electron on March 09, 2013, 09:36:35 pm
The first batch of certificates is online

Serial number 4 (http://www.siliconvalleygarage.com/eevblog/cal/Calibration Certificate 4.pdf)
Serial number 5 (http://www.siliconvalleygarage.com/eevblog/cal/Calibration Certificate 5.pdf)
Serial number 7 (http://www.siliconvalleygarage.com/eevblog/cal/Calibration Certificate 7.pdf)
Serial number 9 (http://www.siliconvalleygarage.com/eevblog/cal/Calibration Certificate 9.pdf)
Serial number 12 (http://www.siliconvalleygarage.com/eevblog/cal/Calibration Certificate 12.pdf)
Serial number 14 (http://www.siliconvalleygarage.com/eevblog/cal/Calibration Certificate 14.pdf)
Serial number 15 (http://www.siliconvalleygarage.com/eevblog/cal/Calibration Certificate 15.pdf)
Serial number 16 (http://www.siliconvalleygarage.com/eevblog/cal/Calibration Certificate 16.pdf)
Serial number 17 (http://www.siliconvalleygarage.com/eevblog/cal/Calibration Certificate 17.pdf)
Serial number 18 (http://www.siliconvalleygarage.com/eevblog/cal/Calibration Certificate 18.pdf)
Serial number 36 (http://www.siliconvalleygarage.com/eevblog/cal/Calibration Certificate 36.pdf)
Serial number 46 (http://www.siliconvalleygarage.com/eevblog/cal/Calibration Certificate 46.pdf)
Serial number 53 (http://www.siliconvalleygarage.com/eevblog/cal/Calibration Certificate 53.pdf)
Serial number 63 (http://www.siliconvalleygarage.com/eevblog/cal/Calibration Certificate 63.pdf)


The assembly manual is here :

Assembly manual (http://www.siliconvalleygarage.com/eevblog/cal/assembly manual.pdf)
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: BravoV on March 10, 2013, 08:39:01 am
Vincent, did you use the same voltage to all cal kits ? or you adjusted each until it started to avalanche ?

Also did any of those transistors toasted while testing those high voltages ? Short life as expected, but for how long ?
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: free_electron on March 10, 2013, 04:02:03 pm
Same voltage on all. I dropped the 24k to 20k to get consistent avalanching. The kits have the 20k resistor.

I'll post a picture of the test jig.

Havent froed a transistor yet. I had one running u til the battery was empty. Still works fine.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: BravoV on March 14, 2013, 03:06:27 am
Same voltage on all. I dropped the 24k to 20k to get consistent avalanching. The kits have the 20k resistor.

I'll post a picture of the test jig.

Havent froed a transistor yet. I had one running u til the battery was empty. Still works fine.
Whats the lowest voltage that you've tested ?
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: nadona on March 15, 2013, 05:04:18 am
My 60 years old eyes new to SMD soldering was hesitant for a days, but finally let it go.
There is no pulse and no LED.

A different set of eyes will catch any mistakes I made.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: amspire on March 15, 2013, 05:19:25 am
Looks to me like something is going between the right hand side of C6 and the top left two pins of U1
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: marshallh on March 15, 2013, 05:21:36 am
Very good pictures. The only thing I can see offhand is maybe a spec of solder bridging pin 1 of the Linear chip with an adjacent capacitor.
Could also be problem with the diodes' polarities. The middle diode is reversed from the others. The cathodes are very faintly marked.

You will also need a brand new coin cell. I was able to use a 4 year old cell after jumpstarting it with a 3.7v lipo. But otherwise it would not start up.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: HackedFridgeMagnet on March 15, 2013, 05:32:48 am
Also L1 looks like it may have been damaged.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: BravoV on March 15, 2013, 05:35:14 am
Yep, same observation as others, and its quite hard to see the diode's polarity marking even I've enhanced your photo like below.

(https://www.eevblog.com/forum/blog/eevblog-306-jim-williams-pulse-generator/?action=dlattach;attach=41320;image)
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: nadona on March 15, 2013, 05:41:51 am
Putting in a brand-new battery fixed the problem! Thank you amspire and marshallh.

Is this pulse right? This is using a LeCroy LC584AL I received this afternoon.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: marshallh on March 15, 2013, 06:10:24 am
Yes, it's working.. but you are using a passive x10 probe. Your measurements will be limited by this.

Set the scope to DC 50ohm input and connect the avalancher directly to the BNC. The Lecroy frontend in 50ohm mode is rated for 5V RMS but you should be fine.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: sdscotto on March 17, 2013, 06:16:18 pm
Any updates on the next batch going out?

TIA
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: free_electron on March 17, 2013, 09:40:42 pm
next batch leaves tuesday. assembling boxes and sticking labels right now :)
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: BravoV on March 18, 2013, 05:32:43 am
Finally ... thanks Vincent !  :-+
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: nack on March 21, 2013, 11:20:15 pm
Darn, missed the first batch. And now I realize you have been shipping out a version two. Any possibility for me to still order a unit Vincent?
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: free_electron on March 24, 2013, 11:03:29 pm
And an update :

Shipment

                  Kit   : CAL  :  PCB: PM : PAID : SHIPPED
alfbaz                  :  2x  :  3x : pm : PAID : serial 48 / 58
andyturk                :  1x  :     : pm : PAID : serial 4
Barryg41                :  1x  :     : PM : PAID : serial 5
biot                    :  1x  :     : PM : PAID : serial 45
BravoV             1x   :  1x  :     : PM : PAID : serial 62    with BFG
blackknife         1x   :      :     : pm :      :
casinada                :  1x  :     : pm : PAID : serial 18
circuitous              :  1x  :     : pm : PAID : serial 17
Christe4nM              :  1x  :  1x : pm : PAID : serial 47
condor                  :  1x  :     : pm : PAID : serial 7
cyr                     :  1x  :     : pm : PAID : serial 28
echo88             1x   :  1x  :     : pm : PAID : serial 31
enz                     :  1x  :     : pm : PAID : serial 40
EV                      :  2x  :     : pm : PAID : serial 32 / 60
fmaimon            1x   :  1x  :     : pm : PAID : serial 50      bfg
g7psk                   :  1x  :     : PM : PAID : serial 66
gibbled            1x   :      :  1x : pm : PAID : shipped
grenert                 :  1x  :     : pm : PAID : serial 12
komet                   :  1X  :     : PM : PAID : serial 21
marshallh               :  1x  :     : pm : PAID : serial 15
nadona                  :  1x  :     : pm : PAID : serial 53
Neganur                 :  2x  :     : pm : PAID : serial 43 / 54
noize                   :  1x  :     : PM : paid : serial 20
olegjay                 :  2x  :  2x : pm : PAID : serial 63 / 16
olepr01@gmail.com  1x   :      :     : pm : PAID : shipped
plesa              1x   :      :  1x : pm : PAID : shipped
robrenz                 :  1x  :     : pm : PAID : serial 9
sdscotto                :  3x  :     : pm : PAID :
Spelunker          1x   :      :     : pm :      :
sCuba              1x   :  1x  :     : PM : PAID : serial 49
teneyes            1x   :  1x  :     : pm : PAID : serial 14
Tymm                    :  2x  : 1x  : pm : PAID : serial 46 / 36
Wsalden            2x   :      :     : pm : PAID : shipped

------------------------------------
                  11x   : 33x  :  10x


Calibration Paperwork

Serial number 4 (http://www.siliconvalleygarage.com/eevblog/cal/Calibration Certificate 4.pdf)
Serial number 5 (http://www.siliconvalleygarage.com/eevblog/cal/Calibration Certificate 5.pdf)
Serial number 7 (http://www.siliconvalleygarage.com/eevblog/cal/Calibration Certificate 7.pdf)
Serial number 9 (http://www.siliconvalleygarage.com/eevblog/cal/Calibration Certificate 9.pdf)
Serial number 12 (http://www.siliconvalleygarage.com/eevblog/cal/Calibration Certificate 12.pdf)
Serial number 14 (http://www.siliconvalleygarage.com/eevblog/cal/Calibration Certificate 14.pdf)
Serial number 15 (http://www.siliconvalleygarage.com/eevblog/cal/Calibration Certificate 15.pdf)
Serial number 16 (http://www.siliconvalleygarage.com/eevblog/cal/Calibration Certificate 16.pdf)
Serial number 17 (http://www.siliconvalleygarage.com/eevblog/cal/Calibration Certificate 17.pdf)
Serial number 18 (http://www.siliconvalleygarage.com/eevblog/cal/Calibration Certificate 18.pdf)
Serial number 20 (http://www.siliconvalleygarage.com/eevblog/cal/Calibration Certificate 20.pdf)
Serial number 21 (http://www.siliconvalleygarage.com/eevblog/cal/Calibration Certificate 21.pdf)
Serial number 28 (http://www.siliconvalleygarage.com/eevblog/cal/Calibration Certificate 28.pdf)
Serial number 31 (http://www.siliconvalleygarage.com/eevblog/cal/Calibration Certificate 31.pdf)
Serial number 32 (http://www.siliconvalleygarage.com/eevblog/cal/Calibration Certificate 32.pdf)
Serial number 36 (http://www.siliconvalleygarage.com/eevblog/cal/Calibration Certificate 36.pdf)
Serial number 40 (http://www.siliconvalleygarage.com/eevblog/cal/Calibration Certificate 40.pdf)
Serial number 43 (http://www.siliconvalleygarage.com/eevblog/cal/Calibration Certificate 43.pdf)
Serial number 45 (http://www.siliconvalleygarage.com/eevblog/cal/Calibration Certificate 45.pdf)
Serial number 46 (http://www.siliconvalleygarage.com/eevblog/cal/Calibration Certificate 46.pdf)
Serial number 47 (http://www.siliconvalleygarage.com/eevblog/cal/Calibration Certificate 47.pdf)
Serial number 48 (http://www.siliconvalleygarage.com/eevblog/cal/Calibration Certificate 48.pdf)
Serial number 53 (http://www.siliconvalleygarage.com/eevblog/cal/Calibration Certificate 53.pdf)
Serial number 54 (http://www.siliconvalleygarage.com/eevblog/cal/Calibration Certificate 54.pdf)
Serial number 58 (http://www.siliconvalleygarage.com/eevblog/cal/Calibration Certificate 58.pdf)
Serial number 60 (http://www.siliconvalleygarage.com/eevblog/cal/Calibration Certificate 60.pdf)
Serial number 63 (http://www.siliconvalleygarage.com/eevblog/cal/Calibration Certificate 63.pdf)
Serial number 66 (http://www.siliconvalleygarage.com/eevblog/cal/Calibration Certificate 66.pdf)

The assembly manual is here :

Assembly manual (http://www.siliconvalleygarage.com/eevblog/cal/assembly manual.pdf)
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: BravoV on March 25, 2013, 03:26:20 am
Paperwork for serial #62 ?   :'(
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: sdscotto on March 25, 2013, 06:39:29 pm
Guess I should have checked here instead of waiting by the mailbox.   Any estimate on when the next batch goes out?
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: EV on April 03, 2013, 09:22:37 am
I got the kits today, Thanks!
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: G7PSK on April 03, 2013, 10:05:07 am
Joy oh joy and jubilations the kit arrived today. Thank you, now comes the fun!
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: EV on April 05, 2013, 08:38:37 am
In picure rise time 20% - 80% with Tektronix TDS3032. Tester MK2 is connected to scope with sma/BNC adaptor and 20 dB attenautor.

Edit: New picture witout 20 cm RG174 cable.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: BravoV on April 05, 2013, 09:17:52 am
EV, is that extra 20cm cable was intentional ? How about direct SMA to BNC socket result ?
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: EV on April 05, 2013, 10:42:29 am
EV, is that extra 20cm cable was intentional ? How about direct SMA to BNC socket result ?

I have not SMA BNC adapter yet, but I have ordered it.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: EV on April 05, 2013, 10:45:37 am
In picure is rise time 20% - 80% with Rigol GS2202. Tester MK2 is connected to scope with 20 cm RG174 cable and 50 ohm feed thru terminator.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: jpb on April 05, 2013, 11:07:00 am
In picure rise time 20% - 80% with Tektronix TDS3032. Tester MK2 is connected to scope with 20 cm RG174 cable and 20 dB attenautor.

That seems in good agreement with the nominal Bandwidth of 300MHz.

For tau rise from 20% to 80% and 300 MHz BW the rise time should be

(ln(0.8/0.2)/(2.pi))/300MHz = 735 psecs and you're measuring around 700 psecs which seems pretty close.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: jpb on April 05, 2013, 11:12:03 am
In picure is rise time 20% - 80% with Rigol GS2202. Tester MK2 is connected to scope with 20 cm RG174 cable and 50 ohm feed thru terminator.
The Rigol seems to be doing a bit better than nominal, the nominal 20% to 80% rise time for 200MHz BW I calculate as 1.1 nsec whilst you're measuring 960psecs which would correspond to around 230 MHz BW.

The pulse generator seems to do a good job on your two scopes.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: robrenz on April 05, 2013, 11:18:31 am
In picure rise time 20% - 80% with Tektronix TDS3032. Tester MK2 is connected to scope with 20 cm RG174 cable and 20 dB attenautor.

That seems in good agreement with the nominal Bandwidth of 300MHz.

For tau rise from 20% to 80% and 300 MHz BW the rise time should be

(ln(0.8/0.2)/(2.pi))/300MHz = 735 psecs and you're measuring around 700 psecs which seems pretty close.

Don't you need to subtract out the calibrated rise time of the pulser from the displayed rise time to get the real rise time first?
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: jpb on April 05, 2013, 12:11:54 pm
In picure rise time 20% - 80% with Tektronix TDS3032. Tester MK2 is connected to scope with 20 cm RG174 cable and 20 dB attenautor.

That seems in good agreement with the nominal Bandwidth of 300MHz.

For tau rise from 20% to 80% and 300 MHz BW the rise time should be

(ln(0.8/0.2)/(2.pi))/300MHz = 735 psecs and you're measuring around 700 psecs which seems pretty close.


Don't you need to subtract out the calibrated rise time of the pulser from the displayed rise time to get the real rise time first?

I'm not an expert on this but I think it is not a simple subtraction. For uncoupled systems I think it is the square root of the sum of the squares of the separate taus.
So, if that is the case, you need to square the tau, subtract the square of the pulse generator tau and then take the square root.

see the bit on cascaded blocks in Wikipedia:

http://en.wikipedia.org/wiki/Rise_time (http://en.wikipedia.org/wiki/Rise_time)

If the pulse generator tau is around 200 psecs then 700 psecs should in fact be 671 psecs. The 960 psec should be 939 psecs.

So, yes you're correct in that they need correcting but the difference is not huge. It would be much more significant for higher BW scopes.

Doing these corrections the BW of the nominal 300MHz scope is around 330MHz and the BW of the 200MHz is 235MHz which seem very reasonable numbers given that I guess manufacturers aim to be plus 10% to ensure that they meet the specification and also it is a pretty approximate measurement in the first place and is making the approximation that the behaviour is governed by a single pole (is essentially a simple RC circuit).

I'm quite impressed by how close it gets.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: fmaimon on April 05, 2013, 04:18:54 pm
Any news on the shipping and data of the serial number 50? I'm very curious of the results...
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: BravoV on April 09, 2013, 01:43:47 am
Paperwork for serial #62 ?   :'(
Any news on the shipping and data of the serial number 50? I'm very curious of the results...

Felipe, looks like both of us have the same faith.  :-//
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: e-pirate on April 09, 2013, 03:52:07 pm
2 free_electron: well, seems that your design is one of the best possible and proven. Is it possible to get your current layout as a picture of both layers in "look through" mode without silk screen and masks, just traces and parts? The screenshot  will do. I've got the main idea how you made the output part, but want to check out details.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: free_electron on April 10, 2013, 01:10:39 am
i'm dropping of another load of packages today at the post office. last week was so busy i didn't get around to it.

@ e-rpiest : i can send you the gerber if you want. I don't care. this design is released as public domain.
You just can't put the text 'Made in a siliconvalleygarage' on it, as that would be a lie if you desing the board :)

i still got some blank boards. 2$ for a pcb ... and a 1.5$ stamp sends it anywhere in the world...
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: notsob on April 10, 2013, 01:27:16 am
Vincent,I have your original unit. I  think I'll try your version two, would you mind giving me a price for the PCB a couple of trannys and the IC.

Cheers,

Peter
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: nack on April 10, 2013, 09:39:30 am
i'm dropping of another load of packages today at the post office. last week was so busy i didn't get around to it.

@ e-rpiest : i can send you the gerber if you want. I don't care. this design is released as public domain.
You just can't put the text 'Made in a siliconvalleygarage' on it, as that would be a lie if you desing the board :)

i still got some blank boards. 2$ for a pcb ... and a 1.5$ stamp sends it anywhere in the world...

Regarding the blank boards, I have send you a message. Thanks.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: jpb on April 10, 2013, 10:23:29 am
i'm dropping of another load of packages today at the post office. last week was so busy i didn't get around to it.

@ e-rpiest : i can send you the gerber if you want. I don't care. this design is released as public domain.
You just can't put the text 'Made in a siliconvalleygarage' on it, as that would be a lie if you desing the board :)

i still got some blank boards. 2$ for a pcb ... and a 1.5$ stamp sends it anywhere in the world...

Regarding the blank boards, I have send you a message. Thanks.

So have I  :)
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: AlfBaz on April 10, 2013, 12:50:28 pm
Received my kits today, thanks Vincent  :-+
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: free_electron on April 10, 2013, 03:15:57 pm
Ok , post office drop was successful. I will cut the remaining orders tonight ( i need to cut the case openings ).

Then i will know exactly what i have left. I will post tonight what is still availalble. People who already mailed me are first in queueu of course.

I have several calibrated kits availalble as well as parts and pcb's.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: enz on April 10, 2013, 09:00:45 pm
I also received mine yesterday, thanks.

Martin
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: Christe4nM on April 12, 2013, 08:05:47 pm
Mine's in as well, and quite well packaged free_electron! Nicely separated little bags for the components. I liked opening that one, so a big :-+ for that alone. Now let's see when I can find the time to solder the thing. :-/O
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: e-pirate on April 17, 2013, 07:32:06 am
Is it a good idea to mount SMD trim cap instead of 2 pF on the collector, I have some 1.4-4 pF?
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: fmaimon on April 17, 2013, 01:14:16 pm
Ok , post office drop was successful. I will cut the remaining orders tonight ( i need to cut the case openings ).

Then i will know exactly what i have left. I will post tonight what is still availalble. People who already mailed me are first in queueu of course.

I have several calibrated kits availalble as well as parts and pcb's.

Did you ship mine? And how about the calibration screen shots?
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: free_electron on April 17, 2013, 01:50:57 pm
I will post the final cal screenshots this weekend. Last batch goes out the door tomorrow. Fmaimon was in the last batch.(last week)
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: jpb on April 17, 2013, 02:25:14 pm
Ok , post office drop was successful. I will cut the remaining orders tonight ( i need to cut the case openings ).

Then i will know exactly what i have left. I will post tonight what is still availalble. People who already mailed me are first in queueu of course.

I have several calibrated kits availalble as well as parts and pcb's.
Hi free_electron,

I just wanted to check that by "mailed me" you mean pm on this forum (rather than e-mail)? I realise that you're very busy at the moment, but I just want to check that the pms I've sent have been sufficient to get my name on the waiting list even though you've not had the chance to reply directly.

jpb
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: ml-eng on April 17, 2013, 02:41:34 pm
Hi, are there one or two pieces left over for sale? I would I would buy them immediatly. 
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: free_electron on April 17, 2013, 02:56:44 pm
I have leftovers yes. Hang in there.
Its busy time and then there is the orders from the other forum i need to take care off as well.
By this weekend everything will be shipped and i will have a clear picture of what is left
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: ml-eng on April 17, 2013, 03:21:53 pm
Thank you, I will watch the thread.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: fmaimon on April 17, 2013, 04:06:06 pm
I will post the final cal screenshots this weekend. Last batch goes out the door tomorrow. Fmaimon was in the last batch.(last week)

Thank you!  :-+
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: BravoV on April 18, 2013, 03:40:15 am
I will post the final cal screenshots this weekend. Last batch goes out the door tomorrow. Fmaimon was in the last batch.(last week)

Was that mine included or its already shipped at previous shipping batch ?
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: free_electron on April 18, 2013, 06:25:26 am
Yours went out last week.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: BravoV on April 18, 2013, 06:34:20 am
Thank you.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: G7PSK on April 19, 2013, 08:52:24 pm
Well I finally put mine together, got a fright when it would not turn on not even the led would light up, I thought the chip might be the wrong way round, turned out that a small piece of plastic film on the battery just where the contact was, why do they hve to wrap every thing in the stuff, no proper test results yet as I have got to get connections and terminators.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: BravoV on April 20, 2013, 03:57:30 am
Got my kits today, I really appreciate the effort done to pack those tiny buggers into different small bags.  :-+

Also thanks a lot for the little 9 GHz beast.  :-+

Now the hardest part, finding the time to assemble and thoroughly test both kits.  ...<sigh> .. :'(
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: BravoV on April 25, 2013, 09:41:28 am
I will post the final cal screenshots this weekend. Last batch goes out the door tomorrow. Fmaimon was in the last batch.(last week)

Vincent, understand you're busy, any chance to post the rest of the cal screenshots this weekend ? tia
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: free_electron on April 25, 2013, 01:37:38 pm
Yep. Absolutely. Everything is out the door now. Weekdays are difficult. By the time i'm done at work i can't see a computer anymore . It's crunch time..
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: kcozens on April 29, 2013, 07:05:59 am
I only recently saw the EEVblog video about the pulse generator. Are any more kits available?
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: free_electron on April 29, 2013, 02:56:52 pm
I'll post an updat tonight. Everything os put the door. There are kits and cals left and a few bare boards as welll. How many ... I need to cou t em.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: uoficowboy on May 03, 2013, 06:40:46 pm
I'll post an updat tonight. Everything os put the door. There are kits and cals left and a few bare boards as welll. How many ... I need to cou t em.
I would be interested as well!
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: e-pirate on May 04, 2013, 07:16:48 pm
Is it critical to use 50 ohm resistor on the output? I have 50.85 (handpicked out of a dozen of 51), can I use it?
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: c4757p on May 04, 2013, 07:46:59 pm
No, it must be 50.00000000  :P

That's within 2% of 50. I'd say it's quite close enough.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: free_electron on May 05, 2013, 04:05:54 am
Here is what is left :

3 kits ( uncalibrated )
8 calibrated versions

no more bare boards.

there are people who already contacted me so these get priority ( if they still want one )

i actually have 10 calibrated versions left but i'm hanging on to two as i have not had confirmation from everyone that they received theirs... you never know. stuff can get lost in the mail .especially to 'certain' countries. once i have confirmation from everyone i will release these as well.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: BravoV on May 05, 2013, 04:10:47 am
Vincent, the rest of those unposted cal screen shots please.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: Neganur on May 05, 2013, 08:36:22 am
Sorry if I missed you asking for confirmation; still swamped with work.
The items arrived in the beginning of April. Ty!
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: free_electron on May 05, 2013, 02:30:47 pm
Ah yes. I will post the other screenshots today.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: free_electron on May 07, 2013, 02:37:01 am
right, the people who were in the 'pending' queue have all got an email with instructions.
if you have not had an email ; you are still in the pending queue. don't despair yet !

i am releasing 8 CAL boards and 2 bare PCB's. so 8 people have had an PM with instructions. ( in order i received the requests )

there is actually 3 more CAL boards available but i am holding on to these until it is confirmed everyone has received his package.... just in case one gets lost in the mail i want to have backups. Once i got full confirmation those will be released as well.

If there is enough interest in this thing i will do another PCB run later this year but this will be 'KIT' only. no more CAL. Getting my hands on the "unobtainium scope" is too taxing on my bank of 'favors' :)

I have plenty of the 'gold leaded' NOS transistors.

i will try to post the remaining CAL documents asap. It's a bit 'crunch time' (i got three new 'babies' to deliver...) at work and when i get home i'm not in the mood to stare at computer screens anymore..
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: free_electron on May 07, 2013, 04:00:15 pm
right. people who have jumped the backend :


C4757P     1 cal
John_L     1 cal 1 pcb
rubbrdux   1 cal 1 pcb
carpelux   1 cal
jpb        1 cal
beaker353  1cal

electrowolf 1cal

plex  2cal  <- pending ...


There are 3 other people that have gotten mail but no response yet..

So right now i'm holding as this potentially allocates remaining stock.

The guys above are confirmed and will ship later this week.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: jpb on May 07, 2013, 04:09:56 pm
Thanks Vincent.

I look forward to getting my kit.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: sdscotto on May 07, 2013, 08:22:27 pm
I received my kits yesterday.  Thank you! 

I built one up this morning and put it on my fastest [working] scope, a Tektronix MSO3034.   Photo attached.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: carpelux on May 07, 2013, 08:44:50 pm
Thanks a lot!
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: jpb on May 07, 2013, 09:05:26 pm
I received my kits yesterday.  Thank you! 

I built one up this morning and put it on my fastest [working] scope, a Tektronix MSO3034.   Photo attached.
I'm looking forward to getting my kit. It seems to produce fairly accurate bandwidth measurements on scopes in the 100MHz to 500MHz range.

Your measurements are for a rise of 7 times. The tau of the pulse generator is around 200psecs for 20% to 80% or 4 times so for 7 times I think this would increase to (ln(7)/ln(4))*200psecs or around 280 psecs so the net rise from your measurements is around sqrt(980^2-280^2)psecs or 940 psecs.

The Bandwidth is then approximately (ln(7)/2.pi)/940psecs = 0.31/940psecs = 330MHz which is 10% up on the nominal 300MHz.

All very believable.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: EV on May 07, 2013, 09:33:01 pm
  Photo attached.

Risetimes marked.  :)
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: John_L on May 09, 2013, 09:15:08 am
Thanks Vince
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: jpb on May 09, 2013, 10:41:28 am
Is it ok to connect the pulser straight to the 50ohm input of an oscilloscope rated at 5Vrms (for 50 ohms)?

I have a WaveJet and the specs don't list a peak voltage for 50 ohms, just the rms value of 5V and I guess that though the peak voltage for the pulser is 10V it only lasts 5nsecs and the duty cycle is low. (What is the duty cycle?)

I haven't got my kit yet but I don't possess any attenuators at present and was wondering whether to get a set (they are quite pricey).
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: EV on May 09, 2013, 02:17:36 pm
Is it ok to connect the pulser straight to the 50ohm input of an oscilloscope rated at 5Vrms (for 50 ohms)?

I think that there is no problem. My Tektronix TDS3032 has max 5 VRMS with peaks < ±30 V. Problem was that the max vertical division is 1V/div. That is why the pulse can not be seen completely without attenautor. With attenautor the uppper side of the pulse is not horisontal. Look at my earlier post:

https://www.eevblog.com/forum/blog/eevblog-306-jim-williams-pulse-generator/300/ (https://www.eevblog.com/forum/blog/eevblog-306-jim-williams-pulse-generator/300/)
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: free_electron on May 09, 2013, 02:44:19 pm
It depends on the scope ... It will definitely clip the signal.
I had the same problem when doing the measurement. I used a real divide by two attenuator during the test.

The attenuator is 50 ohms both ways. Meaning it is 50 ohms towards the pulse generator and also matches the 50 ohms of the scope. (Plus we 'calibrated' the attenuator away.)
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: EV on May 13, 2013, 10:16:03 am
I have got now 6 dB attenuator. It is much better than that 20 dB attenuator which I used earlier. The upper side of the pulse is much nearer horisontal line now. I have ordered also 3 dB attenuator which is probably still better and with it the whole pulse can also be seen.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: jpb on May 13, 2013, 10:48:14 am
It depends on the scope ... It will definitely clip the signal.
I had the same problem when doing the measurement. I used a real divide by two attenuator during the test.

The attenuator is 50 ohms both ways. Meaning it is 50 ohms towards the pulse generator and also matches the 50 ohms of the scope. (Plus we 'calibrated' the attenuator away.)
I guess I'll go with an attenuator to be safe.

The WaveJet that I have states that 5Vrms is a maximum for the 50ohm input but it goes up to 2V/div on 50ohms so presumably can show 16Vp-p so should be able to show a 10V pulse without clipping (I'm assuming that you can apply an offset of around -5V.)

SMA attenuators appear to be much higher frequency than BNC ones (18GHz vs 1 or 2GHz) for the same sort of price but I guess it makes little difference as the SMA to BNC adapter is probably only good to a GHz and my scope is 350MHz anyway.

(Hameg do a reasonably priced set of 4 attenuators and a 50ohm pass through rated at 1W and  1GHz with BNC connectors designed for their scopes.)
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: free_electron on May 13, 2013, 01:53:00 pm
Anyone not received his pulsegen yet ?

(Apart from the last 8 buyers. Those leave today or tomorrow. I packcaged them over the weekend)
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: fmaimon on May 13, 2013, 03:01:02 pm
As I'm on vacations, I won't know for another 2 weeks, but I wouldn't be surprised if i still havn't arrived, as the Brazilian Post and customs are very slow... As soon as I get home I'll check.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: w2aew on May 14, 2013, 10:25:00 pm
OK, here are my results from pulse tester #6 (thanks Scotto!).  First is the result using my old Tektronix 2467 which is a 350MHz analog scope.  Cursors are on the approximate 10-90% points.  The next two images are using a homebrew 20dB attenuator (which may slightly slow the results), on a 1GHz Tektronix MDO4104-6 and on a Tektronix 8GHz MSO70804C.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: hgg on May 15, 2013, 06:45:02 am
free_electron, hi !

Can I have a calibrated one as well ??  Do you sell them assembled?
What is the total cost to Greece?
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: SeanB on May 15, 2013, 11:43:18 am
W2aew, I think the scope is the limiting factor here...........

Hgg, I think Vince does have some left, you will have to PM him to see.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: jpb on May 15, 2013, 11:51:11 am
W2aew, I think the scope is the limiting factor here...........

That is true for the first two, but not for the 8GHz scope.

Vince's measurements gave rise times for 20% to 80% whilst W2aew's are for 10% to 90% so will be (ln(9)/ln(4)) times as long approximately (at least that would be the case for a simple exponential type rise as with a Gaussian filter - I'm not so sure about the case for maximally flat input responses as in higher frequency scopes).

So 234psecs for 10% to 90% would correspond to only around 148psecs for 20% to 80%.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: EV on May 15, 2013, 11:59:32 am
W2aew, fine scopes and pictures!  :P
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: hgg on May 15, 2013, 01:54:26 pm
Thanks SeanB, I will.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: BravoV on May 17, 2013, 05:29:52 am
I will post the final cal screenshots this weekend. Last batch goes out the door tomorrow. Fmaimon was in the last batch.(last week)
I'll post an updat tonight. Everything os put the door. There are kits and cals left and a few bare boards as welll. How many ... I need to cou t em.
Ah yes. I will post the other screenshots today.

Shameless bump.  >:D
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: free_electron on May 17, 2013, 01:44:43 pm
I need one of three things :
- invent time travel
- clone myself so there's two of me
- days of 48 hours ...

I'll try posting the rest tonoght.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: AlfBaz on May 17, 2013, 02:13:30 pm
I need one of three things :
- invent time travel
- clone myself so there's two of me
- days of 48 hours ...

I'll try posting the rest tonoght.
Gees you're a wimp, there's at least another 8 hours you are wasting with sleep! :)
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: Teneyes on May 17, 2013, 02:16:24 pm
Be Nice

Be Positive to catch more Free Electrons
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: free_electron on May 19, 2013, 03:52:27 pm
Allright, here's all the cal certificates (shees,h i'm missing out some quality time floating in the pool...)

Serial number 1 (http://www.siliconvalleygarage.com/eevblog/cal/Calibration Certificate 1.pdf)
Serial number 2 (http://www.siliconvalleygarage.com/eevblog/cal/Calibration Certificate 2.pdf)
Serial number 3 (http://www.siliconvalleygarage.com/eevblog/cal/Calibration Certificate 3.pdf)
Serial number 4 (http://www.siliconvalleygarage.com/eevblog/cal/Calibration Certificate 4.pdf)
Serial number 5 (http://www.siliconvalleygarage.com/eevblog/cal/Calibration Certificate 5.pdf)
Serial number 6 (http://www.siliconvalleygarage.com/eevblog/cal/Calibration Certificate 6.pdf)
Serial number 7 (http://www.siliconvalleygarage.com/eevblog/cal/Calibration Certificate 7.pdf)
Serial number 8 (http://www.siliconvalleygarage.com/eevblog/cal/Calibration Certificate 8.pdf)
Serial number 9 (http://www.siliconvalleygarage.com/eevblog/cal/Calibration Certificate 9.pdf)
Serial number 10 (http://www.siliconvalleygarage.com/eevblog/cal/Calibration Certificate 10.pdf)
Serial number 11 (http://www.siliconvalleygarage.com/eevblog/cal/Calibration Certificate 11.pdf)
Serial number 12 (http://www.siliconvalleygarage.com/eevblog/cal/Calibration Certificate 12.pdf)
Serial number 13 (http://www.siliconvalleygarage.com/eevblog/cal/Calibration Certificate 13.pdf)
Serial number 14 (http://www.siliconvalleygarage.com/eevblog/cal/Calibration Certificate 14.pdf)
Serial number 15 (http://www.siliconvalleygarage.com/eevblog/cal/Calibration Certificate 15.pdf)
Serial number 16 (http://www.siliconvalleygarage.com/eevblog/cal/Calibration Certificate 16.pdf)
Serial number 17 (http://www.siliconvalleygarage.com/eevblog/cal/Calibration Certificate 17.pdf)
Serial number 18 (http://www.siliconvalleygarage.com/eevblog/cal/Calibration Certificate 18.pdf)
Serial number 19 (http://www.siliconvalleygarage.com/eevblog/cal/Calibration Certificate 19.pdf)
Serial number 20 (http://www.siliconvalleygarage.com/eevblog/cal/Calibration Certificate 20.pdf)
Serial number 21 (http://www.siliconvalleygarage.com/eevblog/cal/Calibration Certificate 21.pdf)
Serial number 22 (http://www.siliconvalleygarage.com/eevblog/cal/Calibration Certificate 22.pdf)
Serial number 23 (http://www.siliconvalleygarage.com/eevblog/cal/Calibration Certificate 23.pdf)
Serial number 24 (http://www.siliconvalleygarage.com/eevblog/cal/Calibration Certificate 24.pdf)
Serial number 25 (http://www.siliconvalleygarage.com/eevblog/cal/Calibration Certificate 25.pdf)
Serial number 26 (http://www.siliconvalleygarage.com/eevblog/cal/Calibration Certificate 26.pdf)
Serial number 27 (http://www.siliconvalleygarage.com/eevblog/cal/Calibration Certificate 27.pdf)
Serial number 28 (http://www.siliconvalleygarage.com/eevblog/cal/Calibration Certificate 28.pdf)
Serial number 29 (http://www.siliconvalleygarage.com/eevblog/cal/Calibration Certificate 29.pdf)
Serial number 30 (http://www.siliconvalleygarage.com/eevblog/cal/Calibration Certificate 30.pdf)
Serial number 31 (http://www.siliconvalleygarage.com/eevblog/cal/Calibration Certificate 31.pdf)
Serial number 32 (http://www.siliconvalleygarage.com/eevblog/cal/Calibration Certificate 32.pdf)
Serial number 33 (http://www.siliconvalleygarage.com/eevblog/cal/Calibration Certificate 33.pdf)
Serial number 34 (http://www.siliconvalleygarage.com/eevblog/cal/Calibration Certificate 34.pdf)
Serial number 35 (http://www.siliconvalleygarage.com/eevblog/cal/Calibration Certificate 35.pdf)
Serial number 36 (http://www.siliconvalleygarage.com/eevblog/cal/Calibration Certificate 36.pdf)
Serial number 37 (http://www.siliconvalleygarage.com/eevblog/cal/Calibration Certificate 37.pdf)
Serial number 38 (http://www.siliconvalleygarage.com/eevblog/cal/Calibration Certificate 38.pdf)
Serial number 39 (http://www.siliconvalleygarage.com/eevblog/cal/Calibration Certificate 39.pdf)
Serial number 40 (http://www.siliconvalleygarage.com/eevblog/cal/Calibration Certificate 40.pdf)
Serial number 41 (http://www.siliconvalleygarage.com/eevblog/cal/Calibration Certificate 41.pdf)
Serial number 42 (http://www.siliconvalleygarage.com/eevblog/cal/Calibration Certificate 42.pdf)
Serial number 43 (http://www.siliconvalleygarage.com/eevblog/cal/Calibration Certificate 43.pdf)
Serial number 44 (http://www.siliconvalleygarage.com/eevblog/cal/Calibration Certificate 44.pdf)
Serial number 45 (http://www.siliconvalleygarage.com/eevblog/cal/Calibration Certificate 45.pdf)
Serial number 46 (http://www.siliconvalleygarage.com/eevblog/cal/Calibration Certificate 46.pdf)
Serial number 47 (http://www.siliconvalleygarage.com/eevblog/cal/Calibration Certificate 47.pdf)
Serial number 48 (http://www.siliconvalleygarage.com/eevblog/cal/Calibration Certificate 48.pdf)
Serial number 49 (http://www.siliconvalleygarage.com/eevblog/cal/Calibration Certificate 49.pdf)
Serial number 50 (http://www.siliconvalleygarage.com/eevblog/cal/Calibration Certificate 50.pdf)
Serial number 51 (http://www.siliconvalleygarage.com/eevblog/cal/Calibration Certificate 51.pdf)
Serial number 52 (http://www.siliconvalleygarage.com/eevblog/cal/Calibration Certificate 52.pdf)
Serial number 53 (http://www.siliconvalleygarage.com/eevblog/cal/Calibration Certificate 53.pdf)
Serial number 54 (http://www.siliconvalleygarage.com/eevblog/cal/Calibration Certificate 54.pdf)
Serial number 55 (http://www.siliconvalleygarage.com/eevblog/cal/Calibration Certificate 55.pdf)
Serial number 56 (http://www.siliconvalleygarage.com/eevblog/cal/Calibration Certificate 56.pdf)
Serial number 57 (http://www.siliconvalleygarage.com/eevblog/cal/Calibration Certificate 57.pdf)
Serial number 58 (http://www.siliconvalleygarage.com/eevblog/cal/Calibration Certificate 58.pdf)
Serial number 59 (http://www.siliconvalleygarage.com/eevblog/cal/Calibration Certificate 59.pdf)
Serial number 60 (http://www.siliconvalleygarage.com/eevblog/cal/Calibration Certificate 60.pdf)
Serial number 61 (http://www.siliconvalleygarage.com/eevblog/cal/Calibration Certificate 61.pdf)
Serial number 62 (http://www.siliconvalleygarage.com/eevblog/cal/Calibration Certificate 62.pdf)
Serial number 63 (http://www.siliconvalleygarage.com/eevblog/cal/Calibration Certificate 63.pdf)
Serial number 64 (http://www.siliconvalleygarage.com/eevblog/cal/Calibration Certificate 64.pdf)
Serial number 65 (http://www.siliconvalleygarage.com/eevblog/cal/Calibration Certificate 66.pdf)
Serial number 66 (http://www.siliconvalleygarage.com/eevblog/cal/Calibration Certificate 66.pdf)
Serial number 67 (http://www.siliconvalleygarage.com/eevblog/cal/Calibration Certificate 67.pdf)
Serial number 68 (http://www.siliconvalleygarage.com/eevblog/cal/Calibration Certificate 68.pdf)
Serial number 69 (http://www.siliconvalleygarage.com/eevblog/cal/Calibration Certificate 69.pdf)
Serial number 70 (http://www.siliconvalleygarage.com/eevblog/cal/Calibration Certificate 70.pdf)
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: c4757p on May 19, 2013, 05:56:43 pm
(Apart from the last 8 buyers. Those leave today or tomorrow. I packcaged them over the weekend)

Have you mailed these yet?
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: Teneyes on May 19, 2013, 06:27:11 pm
@BravoV
  Will you be nitpicking about the Standard deviation in the values of Risetimes of Free's workmanship ::)
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: JimmyMz on May 19, 2013, 09:08:42 pm
Free_Electron, you have a PM.  :)
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: BravoV on May 21, 2013, 01:29:38 am
Allright, here's all the cal certificates (shees,h i'm missing out some quality time floating in the pool...)

Finally, thank you !  :clap:

Don't worry, that pool ain't going anywhere.  ;D


@BravoV
  Will you be nitpicking about the Standard deviation in the values of Risetimes of Free's workmanship ::)

Nahh.. I'm content, FreeElectron did the cherry picking for me, the one I got has the fastest Tr , close to that Agilent DSA-X 93204A limit, a braggin sub < 100ps.  >:D
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: c4757p on May 22, 2013, 05:39:11 pm
Got mine today!  :-+ Thank you very much. But you forgot my 220R resistors! I want a refund!  ;)

I won't insult it with a scope shot right now - I'm still waiting on a proper SMA-BNC adapter. It's clearly way too fast for the sad excuse for a cable I bodged it to the scope with for a quick "does it work" test. (It does.)
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: free_electron on May 22, 2013, 07:31:34 pm
Got mine today!  :-+ Thank you very much. But you forgot my 220R resistors! I want a refund!  ;)

I won't insult it with a scope shot right now - I'm still waiting on a proper SMA-BNC adapter. It's clearly way too fast for the sad excuse for a cable I bodged it to the scope with for a quick "does it work" test. (It does.)

really ? darn !. ok i'll refund you 0.1 dollarcent. but you need to pay the paypal charge :)

there should be a strip with two resistors in it. those are the 220 ohms.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: c4757p on May 22, 2013, 07:38:22 pm
but you need to pay the paypal charge :)

Damn!

Quote
there should be a strip with two resistors in it. those are the 220 ohms.

Nope. I've got a hundred or so of the things, though, so not a problem  :-+

Very nice job with it, by the way. PCB looks quite professional, and I like the case too. Can't really comment on the actual functionality - not going to get quicker than a handful of nanoseconds down a clip-on China Brand coax with a five-inch ground lead... I could see the pulse dancing around as I twiddled the lead. I'd fart around with a proper probe on the back side of the SMA jack, but I've got a direct SMA-BNC (M-M, so no cable required at all) in my last order to Mouser.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: BravoV on May 24, 2013, 04:40:06 am
Teasing c4757p  >:D  C'mon, you should be properly equipped with these adapters.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: c4757p on May 24, 2013, 04:42:39 am
:) I think this is the first SMA connector that's ever been in my house! Damn mail takes too long, too...
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: plesa on May 27, 2013, 07:10:04 pm
Thanks FreeElectron!
Today I assembled the generator, everything works like a charm.
I connected it to my DSOX3054 and measured rise time about 940ps.
I also connected the N2792A 200 MHz 10:1 Differential Probe and it has rise time 2,94ns, which is about 136 MHz. Which dissapointed me slightly, but still according to spec.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: fmaimon on May 28, 2013, 01:38:07 pm
Just came back home from a 30 day vacation and the package was here waiting for me. As soon as I clear the jet lag I'll assemble it. Thank you.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: c4757p on May 28, 2013, 06:04:22 pm
Beauty! 800ps on a TDS380.  :-+
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: EV on May 28, 2013, 06:36:09 pm
Looks fine! The overshoot is missing from my TDS3032 curve maybe because I must use attenuator to see the whole curve.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: c4757p on May 28, 2013, 08:05:22 pm
The overshoot is probably due to the less than perfect termination. I didn't have a feedthrough handy so I used a T adapter with cap-style terminator. (Unterminated, it was almost completely washed out by reflections.)
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: EV on May 28, 2013, 09:59:34 pm
The overshoot is probably due to the less than perfect termination. I didn't have a feedthrough handy so I used a T adapter with cap-style terminator. (Unterminated, it was almost completely washed out by reflections.)

Does't your scope have 50 ohm input impedance? I did not find it from TDS380 manual. Rise time was 875 ps in the specs for TDS380.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: c4757p on May 28, 2013, 10:07:19 pm
No, it doesn't have selectable impedance, it's always 1M. My 2445A does have 50 ohm inputs, but I didn't bother taking a picture of it because it has much lower bandwidth and I hate farting around with a camera in front of it  :)

Rise time was 875 ps in the specs for TDS380.

So it appears they're using the standard Gaussian 0.35/rt=bw formula - 0.35/875ps = 400MHz. Then I get 438MHz by the same formula. Nice  :-+
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: w2aew on May 30, 2013, 06:42:49 pm
Here's a picture of #6, taken through a 20dB attenuator, into a 33GHz real-time scope:
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: jpb on May 31, 2013, 06:57:46 pm
My kit has just arrived - thank you Vince!

Now all I need to do is find some time over the weekend to make it up.

Edit: I can't make up my kit until I acquire some tweezers! (This is my first foray into SMD soldering.) I've just ordered some from Farnel but they won't arrive until next week - somewhat frustrating.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: musafir on June 01, 2013, 02:04:09 am
Hello
Are any more kits available ?
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: sdscotto on June 01, 2013, 03:30:34 am
Here's a picture of #6, taken through a 20dB attenuator, into a 33GHz real-time scope:

Show off!  ;-)
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: SeanB on June 01, 2013, 05:20:23 am
Here's a picture of #6, taken through a 20dB attenuator, into a 33GHz real-time scope:

Show off!  ;-)

He does work at Tektronix......................

I somehow doubt they buy Agilent scopes for internal use, though they do use Fluke as meter suppliers.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: jpb on June 07, 2013, 10:53:29 pm
I've built up my kit - and it is not working :'(


Having got through two batteries I've connected it to my lab power supply. It draws about 10mA. The voltage at the end of the diode chain is a healthy 106V.

The voltage at the transistor across C2 is 35V. The Voltage across the 50 ohms is 0.33mV which corresponds to 6.6 microAmps. The voltage drop across the 10M R1A is about 71V
so the current through this is approx 7.1 microAmps.

This means, I guess, that Q1 is leaking too much current to reach avalanche at 40V?

The voltage across R5 is 252mV where as it perhaps should be 106V*20k/(10M+20k) =209mV. In the circuit diagram R5 is only 10k whereas on the board layout
and as supplied in the kit it is 20k?

Any suggestions as to what Voltages and currents I should be seeing would be most welcome. Is 7 microAmps very leaky? (I've no idea.)

Should I be connecting a 10M R1? (No R1 came in the kit, I thought R1A replaced it?)

If I added a 10M as R1 then the voltage drop would be halved and the Voltage across Q1 would rise to about 53V potentially (though presumably it would
do what it is supposed to do and breakdown at 40V).

It's nearly midnight so I'm off to bed but any help would be much appreciated.


EDIT (following morning) :

I've added a 10M as R1 and it is now working! :) At least it is avalanching at a rate of just under 40kHz or every 25 microsecs. Q1 looks like around 5M when it is not avalanching, so the circuit is
two 10M in parallel then a 2pF in parallel with 5M so it is not quite as simple as just RC for the time constant - the effective R is 12.5M - I suppose the last bit of charging is stretched out. I've just looked at it with a probe but will properly terminate it and get some plots when I get a bit of time later on today.

The current draw is still about 10mA so most of this is probably the current of the led (around 8mA or so) - so if you want to save battery life disconnect the led.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: jpb on June 08, 2013, 10:11:17 am
Here are some initial screen shots.

The first is for a 50ohm pass through to 1M/12pF input of the scope.

The second is for a direct connection to the 50ohm input of the scope.

The nominal rise time should be 1nsec (it is a 350MHz scope).
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: EV on June 08, 2013, 11:43:15 am
At least it is avalanching at a rate of just under 40kHz or every 25 microsecs.

Pictures look good. Avalancing rate is about 24.6 kHz with my pulse generator when the battery is installed.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: jpb on June 08, 2013, 11:55:52 am
Here is a comparison with the calibration curve measured by Vince on the Agilent super scope.

What I might do as an experiment is take FFTs of both and see if I can get some sort of approximation to the WaveJet's frequency response
(a little ambitious I know, but fun to try!)
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: jpb on June 08, 2013, 12:04:02 pm
At least it is avalanching at a rate of just under 40kHz or every 25 microsecs.

Pictures look good. Avalancing rate is about 24.6 kHz with my pulse generator when the battery is installed.
By adding both R1 and R1a I've reduced the effective resistance from 10M to around 5M so the time constant should be approximately halved so this (very roughly) fits
with your figure (my slightly leaky transistor in parallel with C2 looks like 5M itself so this increases the charging time so it becomes less than the 50kHz that
a simple halving of the resistance would suggest).
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: EV on June 08, 2013, 12:09:25 pm
Here is a comparison with the calibration curve measured by Vince on the Agilent super scope.

The shape of the curve is nearly like with my Tek scope. The overshoot which is in Vince's picture is missing.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: jpb on June 08, 2013, 12:16:11 pm
Here is a comparison with the calibration curve measured by Vince on the Agilent super scope.

The shape of the curve is nearly like with my Tek scope. The overshoot which is in Vince's picture is missing.
Looking at the overshoot, and estimating the frequency of a sin peak that might fit into it, it looks like a peak width
of around 0.2 nsecs corresponding to a period of 0.4 nsecs or 2.5GHz so it is not surprising that a 350MHz scope
misses it. I guess it must be at least 17dB down probably rather more (17dB was a back of the envelope estimate
based on a single pole response).
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: free_electron on June 08, 2013, 02:09:45 pm
I've built up my kit - and it is not working :'(


Having got through two batteries I've connected it to my lab power supply. It draws about 10mA. The voltage at the end of the diode chain is a healthy 106V.

The voltage at the transistor across C2 is 35V. The Voltage across the 50 ohms is 0.33mV which corresponds to 6.6 microAmps. The voltage drop across the 10M R1A is about 71V
so the current through this is approx 7.1 microAmps.

This means, I guess, that Q1 is leaking too much current to reach avalanche at 40V?

The voltage across R5 is 252mV where as it perhaps should be 106V*20k/(10M+20k) =209mV. In the circuit diagram R5 is only 10k whereas on the board layout
and as supplied in the kit it is 20k?

Any suggestions as to what Voltages and currents I should be seeing would be most welcome. Is 7 microAmps very leaky? (I've no idea.)

Should I be connecting a 10M R1? (No R1 came in the kit, I thought R1A replaced it?)

If I added a 10M as R1 then the voltage drop would be halved and the Voltage across Q1 would rise to about 53V potentially (though presumably it would
do what it is supposed to do and breakdown at 40V).

It's nearly midnight so I'm off to bed but any help would be much appreciated.


EDIT (following morning) :

I've added a 10M as R1 and it is now working! :) At least it is avalanching at a rate of just under 40kHz or every 25 microsecs. Q1 looks like around 5M when it is not avalanching, so the circuit is
two 10M in parallel then a 2pF in parallel with 5M so it is not quite as simple as just RC for the time constant - the effective R is 12.5M - I suppose the last bit of charging is stretched out. I've just looked at it with a probe but will properly terminate it and get some plots when I get a bit of time later on today.

The current draw is still about 10mA so most of this is probably the current of the led (around 8mA or so) - so if you want to save battery life disconnect the led.

Looks like you have leakage around the transistor. Did you clean off the flux ? That area needs to be clean !
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: jpb on June 08, 2013, 02:53:06 pm
Looks like you have leakage around the transistor. Did you clean off the flux ? That area needs to be clean !
I didn't because the flux described itself as "no-clean flux" and claims to meet SF-818 for surface insulation resistance what ever that is.
Probably I should have (though it all looks very clean anyway). This was my first ever bit of smd soldering and use of a flux pen so it
has been a bit of a learning curve. Initially no flux came out of the pen at all, but then I actually read the instructions and found you
need to press it down on the point/knib to start the flow!

I'll clean it up with a bit of IPA, though now I have the extra 10M in there it won't make any difference to the behaviour except perhaps
to increase the frequency from 40kHz if it gets rid of the leakage.

The extra leakage mattered when it was preventing the capacitor charging to above 35V, but once avalanche is reached having approximately
5M in parallel presumably is neither here nor there. With the 5M resistance, even with the leakage it should be able to reach avalanche voltages up to
around 55V.

Thanks for the advice, and all the work you put into this project - I am having a lot of fun with it.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: jpb on June 08, 2013, 03:25:21 pm
Following Free_electron's advice, I've thoroughly cleaned everywhere with IPA including the connector. The results are a small but noticeable improvement as can
be seen in the curve.

A slight downside is the varnish on the circuit board goes sticky with IPA but hopefully it will dry out again and anyway it is safely sealed in its box.

Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: jpb on June 08, 2013, 03:50:24 pm
Here is the output curves before and after cleaning - the difference is generally very small but there is visible improvement on the leading edge where it matters.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: van-c on June 29, 2013, 12:35:50 am
Are the kits still available?  If so, I'm very interested in buying one; if not, I'd like to get in on the next backlog.  Please post or PM me with details.
Thanks,

--Van
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: BravoV on July 01, 2013, 06:44:40 am
A bit related to this, just want to thanks Vincent for selling me bunch of these gold doped transistor, and those gold pins are still really shiny after all these years (batch code 87xx).   :-+

Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: sdscotto on July 26, 2013, 03:06:34 am
I wanted to thank Vincent publicly for the work put into this project.  Also a thank you to those of you who have taken the time to advance the project and teach dummies like me how things work.

scotto
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: free_electron on July 26, 2013, 03:44:54 am
A bit related to this, just want to thanks Vincent for selling me bunch of these gold doped transistor, and those gold pins are still really shiny after all these years (batch code 87xx).   :-+

That's real SGS (Sociedad Generale Semiconduttore ) quality ! we be using real gold at 15 microns instead of flimsy 3 micron flash (if its not rhodium )

SGS was a Spinoff from olivetti
ATES (Aquila Tubi E Semiconduttori ) licensed the transistor directly from Shockley ! The fab was in Catania ( which is today still making IC's)
Thomson : borged Secosem , Mostek and others.
SGS-ATES + Thomson  = SGS-Thomson Microelectronics or STmicroelectronics for short.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: alank2 on August 13, 2013, 12:39:50 pm
I wanted to thank Vincent publicly for the work put into this project. 

+1, I can't wait for them to be available again so I can get my hands on one!
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: JuanPC on September 03, 2013, 09:12:44 pm
can someone explain, ¿why make such a complex device?


isn´t easy to make a short circuit, ?
9v or 12v, or 18v, or 24v.

555
relay,
50ohm resistors.
done.
A fuse just in case  :-DD
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: c4757p on September 03, 2013, 09:21:15 pm
There is no way in hell you will get sub-nanosecond rise time from that. The vast inductance of the system will limit it to significantly longer edges.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: JuanPC on September 03, 2013, 09:24:14 pm
There is no way in hell you will get sub-nanosecond rise time from that. The vast inductance of the system will limit it to significantly longer edges.

what kind of inductance has a relay and a couple of resistors?
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: c4757p on September 03, 2013, 09:30:30 pm
At least a few tens of nH, if they are small and you have connected them very carefully. If you want 500ps rise time, that translates to a bandwidth requirement of about 0.35/500ps = 700MHz. 6.28*10nH*700MHz = 44 ohms per 10nH, making this quite significant.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: JuanPC on September 03, 2013, 09:45:41 pm
At least a few tens of nH, if they are small and you have connected them very carefully. If you want 500ps rise time, that translates to a bandwidth requirement of about 0.35/500ps = 700MHz. 6.28*10nH*700MHz = 44 ohms per 10nH, making this quite significant.

the Relays i have here has: 0.000mH
QIANJI JQC-3F(T73)
10A 28VDC / 7A 240VAC
5VDC
Relays have a <10ms Operating Time, and <5ms Release time. = 15ms max period = 555 must not exceed/should operate at  66.667Hz.* i´ve pushed those relays up to 120Hz.

even better...
dual cascaded Relays!!!

18vdc--->555--->Relay1--->Relay2--->5v 50ohms output.
Relays work at 5vDC each.
just a couple of voltage dividers.
done.
(https://www.eevblog.com/forum/blog/eevblog-306-jim-williams-pulse-generator/?action=dlattach;attach=59586)
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: c4757p on September 03, 2013, 10:10:38 pm
Here's my best attempt at measuring the rise time of a mechanical switch. It ain't pretty. The fall time was so bad as to not merit the 60 seconds or so it takes my scope to record a screenshot.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: c4757p on September 03, 2013, 10:16:22 pm
the Relays i have here has: 0.000mH
QIANJI JQC-3F(T73)

Bullshit it has 0.000mH inductance! Show me.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: JuanPC on September 03, 2013, 10:48:11 pm
the Relays i have here has: 0.000mH
QIANJI JQC-3F(T73)

Bullshit it has 0.000mH inductance! Show me.

The Uni-T UT70A is calibrated for the long probes, thats why measures -0.002 with the short alligator clips.
Short Probes -0.002 = 0.000mH
Just for fun added an EMI filter.

Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: c4757p on September 03, 2013, 11:04:01 pm
Datasheet claims 2% + 10 counts on inductance. That means it could read all the way down to 0 for something that's actually 10.2 nH. At the low end, that's not unlikely.

And mechanical switches don't behave as well as you would think, as I just showed. See how the voltage mostly ramps up over a few microseconds, and only speeds up at the end? That's pretty useless for any real measurement.

Also... try zooming into a 1ns edge that only happens at 10 Hz or so on an analog oscilloscope. You could crank the brightness to maximum and still not see it!
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: free_electron on September 03, 2013, 11:17:17 pm
uni-t 'professional multimeter'  :palm:
2millihenry range trying to measure nanohenry's ...  |O

you don't stand a chance with a relay. even a normal transistor can't switch that fast. we are dabbling in the picosecond range with this pulse generator. spanning 8 volts in 200 picoseconds needs something very fast. fast as in atomic physics fast. which is why we use the avalanche effect of driving the transistor in controlled breakdown.
the energy stored in the stripline is released over time to give the top plateau. The stripline is tuned for that so it releases energy correctly.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: BravoV on September 04, 2013, 12:26:15 am
Datasheet claims 2% + 10 counts on inductance. That means it could read all the way down to 0 for something that's actually 10.2 nH. At the low end, that's not unlikely.

And mechanical switches don't behave as well as you would think, as I just showed. See how the voltage mostly ramps up over a few microseconds, and only speeds up at the end? That's pretty useless for any real measurement.

Also... try zooming into a 1ns edge that only happens at 10 Hz or so on an analog oscilloscope. You could crank the brightness to maximum and still not see it!
uni-t 'professional multimeter'  :palm:
2millihenry range trying to measure nanohenry's ...  |O

you don't stand a chance with a relay. even a normal transistor can't switch that fast. we are dabbling in the picosecond range with this pulse generator. spanning 8 volts in 200 picoseconds needs something very fast. fast as in atomic physics fast. which is why we use the avalanche effect of driving the transistor in controlled breakdown.
the energy stored in the stripline is released over time to give the top plateau. The stripline is tuned for that so it releases energy correctly.
Guys, some hints -> HERE (https://www.eevblog.com/forum/testgear/boxcar-averaging-hi-resolution-mode/msg286177/#msg286177) or HERE (https://www.eevblog.com/forum/testgear/inexpensive-diy-50ps-ultra-fast-pulse-generator/msg284235/#msg284235), I guess he has trouble with scales.   :palm:
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: JuanPC on September 04, 2013, 12:35:31 am
uni-t 'professional multimeter'  :palm:
2millihenry range trying to measure nanohenry's ...  |O

you don't stand a chance with a relay. even a normal transistor can't switch that fast. we are dabbling in the picosecond range with this pulse generator. spanning 8 volts in 200 picoseconds needs something very fast. fast as in atomic physics fast. which is why we use the avalanche effect of driving the transistor in controlled breakdown.
the energy stored in the stripline is released over time to give the top plateau. The stripline is tuned for that so it releases energy correctly.

#1. The UNI-T works fine for me.
it measures the probe inductance: 1.2mts vs. 20cm
0.002mH = 2uH,

#2. The 2n2369 is just an old 123AP !!! used for Audio.-
#3.
the word you are looking for is: "krytron, used for extremely precise rapid high-voltage switching. Krytrons with certain specifications are suitable to initiate the precise sequence of detonations used to set off a nuclear weapon, and are heavily controlled at an international level ... This design, dating from the late 1940s, is still capable of pulse-power performance which even the most advanced semiconductors (even IGBTs) cannot match easily. Commutation time: less than 1 nanosecond can be achieved, with a delay between the application of the trigger pulse and switching which can be as low as about 30 nanoseconds. The achievable jitter may be below 5 nanoseconds. "

Wrong, faster than Atomic Bombs.
http://en.wikipedia.org/wiki/Krytron (http://en.wikipedia.org/wiki/Krytron)
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: c4757p on September 04, 2013, 12:44:10 am
Oh dear god, we both missed it. :palm:

0.002mH = 2nH,

No. 0.002mH = 2uH. Micro. One thousand nH. You weren't even looking at nanohenries, you were looking at thousands of nanohenries.

Quote
#2. The 2n2369 is just an old 123AP !!! used for Audio.-

No it's not. It's a "high speed saturating switch". It's made for switching very fast. It will give 1-2ns rise time even just being switched in standard common-emitter configuration. Absolutely ridiculous for audio purposes. Read the datasheet. Spend some time with the one for your multimeter too.

Quote
#3.
the word you are looking for is: "krytron, used for extremely precise rapid high-voltage switching. Krytrons with certain specifications are suitable to initiate the precise sequence of detonations used to set off a nuclear weapon, and are heavily controlled at an international level ... This design, dating from the late 1940s, is still capable of pulse-power performance which even the most advanced semiconductors (even IGBTs) cannot match easily. Commutation time: less than 1 nanosecond can be achieved, with a delay between the application of the trigger pulse and switching which can be as low as about 30 nanoseconds. The achievable jitter may be below 5 nanoseconds. "

Er.... :blah: What does this have to do with fast rise time pulses, exactly?
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: BravoV on September 04, 2013, 12:57:55 am
#2. The 2n2369 is just an old 123AP !!! used for Audio.-

Sigh .. I guess I must be conned by free_electron into buying couple of those 2N2369A "audio" transistors from him.  :-DD
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: JuanPC on September 04, 2013, 01:05:50 am
Oh dear god, we both missed it. :palm:

0.002mH = 2uH,

No. 0.002mH = 2uH. Micro. One thousand nH. You weren't even looking at nanohenries, you were looking at thousands of nanohenries.

Quote
#2. The 2n2369 is just an old 123AP !!! used for Audio.-

No it's not. It's a "high speed saturating switch". It's made for switching very fast. It will give 1-2ns rise time even just being switched in standard common-emitter configuration. Absolutely ridiculous for audio purposes. Read the datasheet. Spend some time with the one for your multimeter too.

Quote
#3.
the word you are looking for is: "krytron, used for extremely precise rapid high-voltage switching. Krytrons with certain specifications are suitable to initiate the precise sequence of detonations used to set off a nuclear weapon, and are heavily controlled at an international level ... This design, dating from the late 1940s, is still capable of pulse-power performance which even the most advanced semiconductors (even IGBTs) cannot match easily. Commutation time: less than 1 nanosecond can be achieved, with a delay between the application of the trigger pulse and switching which can be as low as about 30 nanoseconds. The achievable jitter may be below 5 nanoseconds. "

Er.... :blah: What does this have to do with fast rise time pulses, exactly?

Sorry Typo Mistake. Corrected.

milli m       0.001    thousandth    1795
micro u     0.000001    millionth    1960
nano n     0.000000001    billionth    1960
pico p       0.000000000001    trillionth    1960
femto f     0.000000000000001    quadrillionth    1964
http://en.wikipedia.org/wiki/Nano- (http://en.wikipedia.org/wiki/Nano-)

1H = 1000mH
1mH = 1000uH
1uH = 1000nH
1nH = 1000pH

#2.  :wtf:

(https://www.eevblog.com/forum/blog/eevblog-306-jim-williams-pulse-generator/?action=dlattach;attach=59610)
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: c4757p on September 04, 2013, 01:09:27 am
Yes. Exactly. So that relay could have been all the way up to 10 microhenries and your meter could have read the same. So nanohenries? Forget about it.

Don't even get me started on the utter uselessness of an inductance meter with an error of 10 uH...
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: BravoV on September 04, 2013, 01:18:06 am
#2.  :wtf:

Juan, it looks you're very good at finding article at the internet and you love to quote them on every posts, now, get your favorite "audio" transistor datasheet, and then look for 2N2369A datasheet and start to compare between them.

Yes, I know it looks like an old outdated transistor, but still, please do it. This thread grew into this giant just because of this particular transistor.

Again, please, do it, for your own good sake, cause you're becoming to look like an idiot and worst it looks like you're starting to be proud of it.  :palm:

DO IT NOW !!!  >:(
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: JuanPC on September 04, 2013, 01:30:00 am
#2.  :wtf:

Juan, it looks you're very good at finding article at the internet and you love to quote them on every posts, now, get your favorite "audio" transistor datasheet, and then look for 2N2369A datasheet and start to compare between them.

Yes, I know it looks like an old outdated transistor, but still, please do it. This thread grew into this giant just because of this particular transistor.

Again, please, do it, for your own good sake, cause you're becoming to look like an idiot and worst it looks like you're starting to be proud of it.  :palm:

DO IT NOW !!!  >:(
:)  :-DD

http://pdf.datasheetcatalog.com/datasheet/SGSThomsonMicroelectronics/mXtuvtv.pdf (http://pdf.datasheetcatalog.com/datasheet/SGSThomsonMicroelectronics/mXtuvtv.pdf)
http://www.nteinc.com/specs/100to199/pdf/nte123a.pdf (http://www.nteinc.com/specs/100to199/pdf/nte123a.pdf)
http://www.centralsemi.com/leadedpdf/2n2369a.pdf (http://www.centralsemi.com/leadedpdf/2n2369a.pdf)
2n2369A Rise Time: 9ns-25ns.
Ft Current Gain BW: 300-500Mhz

Rt=0.35/BW
1ns = 350MHz scope ideal.
 :-//
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: alank2 on September 04, 2013, 01:34:00 am
I can't wait for    free_electron to have more kits!!!!!
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: c4757p on September 04, 2013, 01:34:13 am
The 2N2369 will often perform much better than datasheet specs. Note that Jim Williams said that one may have to be selected. I've made them switch with 1-2ns rise time just in the traditional manner, with a very hard drive (100 ohm || 10nF on the base, 100 ohm collector load) and very low emitter inductance (2mm straight to the ground plane).

And it will blow right past that if avalanched.

Check the other specs. They're clearly not the same transistor.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: JuanPC on September 04, 2013, 01:38:07 am
The 2N2369 will often perform much better than datasheet specs. Note that Jim Williams said that one may have to be selected. I've made them switch with 1-2ns rise time just in the traditional manner, with a very hard drive (100 ohm || 10nF on the base, 100 ohm collector load) and very low emitter inductance (2mm straight to the ground plane).

And it will blow right past that if avalanched.

Check the other specs. They're clearly not the same transistor.

Still can´t believe a short circuit can´t perform better.

Maybe a Tesla coil or a TV Flyback connected to a serious voltage divider, why can´t perform better?
 :-DD
(http://www.gravitycontrol.org/forum/images/Tesla-coils.jpg)
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: BravoV on September 04, 2013, 01:51:16 am
Though English is not his native, definitely this is not a language barrier, so its confirmed now that he is not that "bright" isn't it ?   >:D

I'm done and out of here, too bad, this very fine thread is now tainted by this troll.   :'(
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: JuanPC on September 04, 2013, 01:53:16 am
Though English is not his native, definitely this is not a language barrier, so its confirmed now that he is not that "bright" isn't it ?   >:D

I'm done and out of here, too bad, this very fine thread is now tainted by this troll.   :'(
you have: 1589 Posts.
i have: 97.
 :-DD
Troll Envy   :-DD :-DD
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: c4757p on September 04, 2013, 02:37:00 am
Still can´t believe a short circuit can´t perform better.

Still can't believe I can't fly if I flap my arms really fast.

Oh wait. It doesn't work whether or not I believe it should.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: c4757p on September 04, 2013, 02:44:13 am
Maybe a Tesla coil or a TV Flyback connected to a serious voltage divider, why can´t perform better?

Spark gaps actually can have very fast rise times. I'm not sure how they compare to an avalanche transistor. Why don't you try it? You should only need a few hundred volts, not a Tesla coil.

They're also unpredictable, dangerous and noisy as hell... but each to his own...
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: free_electron on September 04, 2013, 02:53:04 am
wrote a truckload of blabla in this and other topics about using audiocard to measure clock risetime
and 1ns = 350MHz scope ideal
What kind of medications are you on ? it's time to pump up the dosage ....

That NTE replacement transistor doesn't come close. the 2N2369 is designed for ultrafast saturated switching applications the NTe for medium speed switching apps... not even saturated switching.
the NTE barely grabs 40ns turn-on time while the 2N2369 is in the 10nS time range. Anyway, the point is irellevant since we are using the transistor in avalanche mode. There is no telling how the NTE will behave as it is not specified in that mode. Avalanching a transistor is non-standard usage and parts are not characterised for that. Jim williams tried many different transistors and found the 2N2369 to be the best out of all. He then hand picked the best out of a batch of those.

Having built and measured 70 of these pulse generators, one the fastest scope around (then, now the Q version doubles its speed)  and done a spread (see below) the design is proven.
All you have done is point at stuff other people have done, and then post your own misinterpretation of it. So shut up and go away.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: c4757p on September 04, 2013, 03:00:25 am
Though English is not his native, definitely this is not a language barrier, so its confirmed now that he is not that "bright" isn't it ?   >:D

Yo hablo un poco español también, quizás él puede hablar conmigo si él tiene un problema.

Aunque, creo que su problema es del tipo médico. No soy un psiquiatra.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: BravoV on September 04, 2013, 05:00:52 am
Though English is not his native, definitely this is not a language barrier, so its confirmed now that he is not that "bright" isn't it ?   >:D

I'm done and out of here, too bad, this very fine thread is now tainted by this troll.   :'(
you have: 1589 Posts.
i have: 97.
 :-DD
Troll Envy   :-DD :-DD

Fully understand a typical post count chasers do when they joined a forum, but I just don't get it on why bother with those efforts and troubles posting all those tons of links, and typing all those long arguments at each post ? Cause only with a simple single line of junk words will also increase the post counter too.

This is it, the 2nd confirmation about the "bright" thingy that I mentioned and I'm guessing the 3rd one is also coming.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: GeoffS on September 04, 2013, 08:38:34 pm
Several useless posts removed.
Can we get this thread back on topic please?
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: dr.diesel on September 04, 2013, 08:40:51 pm
I can't wait for    free_electron to have more kits!!!!!

Agreed.  f_e, if you've got a list going, please add me as well!
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: Lukas on September 05, 2013, 09:52:32 am
Using relays for generating fast-risetime pulses isn't a new idea: http://w140.com/tekwiki/wiki/109 (http://w140.com/tekwiki/wiki/109)
Quote
Using an external voltage source, pulses up to 300V are possible.
Try to replicate that using today's equipment...
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: warp_foo on September 07, 2013, 02:35:14 am
I can't wait for    free_electron to have more kits!!!!!

Agreed.  f_e, if you've got a list going, please add me as well!

+1 more
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: kvitekp on September 08, 2013, 03:47:29 pm
+1 here
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: Dave on September 08, 2013, 04:17:16 pm
+1 :)
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: AlfBaz on September 08, 2013, 04:41:19 pm
I have a scope that's 1GHz into 50ohm and 500MHz into 1Mohm. 50ohm only goes to 1V per division so I'm not quite getting the whole pulse to fit on screen. Do I need to buy an expensive attenuator or is there a cheaper alternative?
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: fmaimon on September 08, 2013, 11:27:14 pm
w2eaw has a solution for you:

Basic RF Attenuators - Design, Construction, Testing - PI and T style - A Tutorial (https://www.youtube.com/watch?v=A5gGeV7CiQ0#ws)
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: AlfBaz on September 09, 2013, 12:40:22 am
w2eaw has a solution for you:
What's going on with my memory? I've already seen that video! :palm:
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: G7PSK on September 09, 2013, 07:29:07 am
w2eaw has a solution for you:
What's going on with my memory? I've already seen that video! :palm:

It needs re-seating in its socket! :-DD
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: AlfBaz on September 09, 2013, 08:52:19 am
It needs re-seating in its socket! :-DD
Thanks, gave me a good chuckle ;D
Although I fear contaminants on the pcb traces are causing clock skew :)
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: BravoV on September 09, 2013, 08:54:49 am
It needs re-seating in its socket! :-DD
Thanks, gave me a good chuckle ;D
Although I fear contaminants on the pcb traces are causing clock skew :)
Easy, get a sniff with a strong inhalation on a single burst of contact cleaner & lubricant, or just plain WD40.  >:D
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: van-c on September 10, 2013, 07:31:19 pm
I can't wait for    free_electron to have more kits!!!!!

free_electron Please add me to the list too.

Speaking of w2eaw's videos, I followed this one: Cheap and simple TDR using an oscilloscope and 74AC14 Schmitt Trigger Inverter (https://www.youtube.com/watch?v=9cP6w2odGUc#ws) to build a Schmitt trigger pulse generator like his example.  I wanted to use his pulse generator do do a sanity check of my 150 MHz Tek 2445A scope's bandwidth. 

I used a BNC connector soldered to the board that directly connected the pulse generator to channel 1 input (no probe used).   I measured a rise time of about 4.4 nS on the 2445A.  The 74AC14 datasheet gives a propagation delay of 1.5nS minimum to 10 nS maximum and typical delay of 7 nS.   So, the rise time of the scope should equal the measured rise time minus the propagation delay of the pulse generator (right?).  Using an estimated delay of, say, 2 nS for the pulse generator itself, that would give a scope rise time of 4.4 - 2.0 = 2.4 nS, or a bandwidth of about 145 MHz, which confirms the sanity check, assuming I am doing this right, i.e., making no invalid assumptions.

Of course, this pulse generator is only useful for bandwidth measurement on scopes where the circuit's delay is small compared to the rise time of the scope.  I would really like to use the JW pulse generator when the kit is available again to get a more accurate measurement.

--Van
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: free_electron on September 10, 2013, 09:14:44 pm
i will try to do another run towards the end of the year. these will be kits only . No calibration as i can't get access to the scope. After the 75 kits built we know where the pulse speed is and there is no real need for calibration as you don't stand a chance getting your hands on a machine that can outrun the pulse generator ( at least not for a few decades )

i'll see if i can get a bulk order of the 2n transistors. i want the original NOS gold legged SGs transistors as they perform well ( every single one tested avalanches correctly ). i still have a few of the transistors but not enough for a second run.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: Sparky on September 10, 2013, 09:26:34 pm
i will try to do another run towards the end of the year. these will be kits only . No calibration as i can't get access to the scope. After the 75 kits built we know where the pulse speed is and there is no real need for calibration as you don't stand a chance getting your hands on a machine that can outrun the pulse generator ( at least not for a few decades )

i'll see if i can get a bulk order of the 2n transistors. i want the original NOS gold legged SGs transistors as they perform well ( every single one tested avalanches correctly ). i still have a few of the transistors but not enough for a second run.

Sounds great!  :D  I sent you a PM a little while back about future kits --- if you are maintaining a short-list, please add me!

Excited!
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: ElectroIrradiator on September 10, 2013, 09:30:56 pm
Yay! :)

+1
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: van-c on September 10, 2013, 11:48:33 pm
That's really good news.
--Van
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: BravoV on September 11, 2013, 05:48:22 am
i'll see if i can get a bulk order of the 2n transistors. i want the original NOS gold legged SGs transistors as they perform well ( every single one tested avalanches correctly ). i still have a few of the transistors but not enough for a second run.

Wait, I thought you got a mountain pile of them ?  ???

Whats the alternative if there are no more of these old nos gold legged SGs ?
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: free_electron on September 11, 2013, 07:11:19 am
I got about 200 left.. Two per kit .. 100 kits.. Still id like to stock a bunch more.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: alank2 on September 11, 2013, 12:07:47 pm
I got about 200 left.. Two per kit .. 100 kits.. Still id like to stock a bunch more.

If there is a list please put me on it.  I can't wait to get my mitts on one!!!!
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: geostep on September 17, 2013, 02:34:52 am
I'm interested as well.  Add me to the "list" as well please.

- George
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: Orpheus on September 21, 2013, 08:08:19 am
I'd like to be on that list, too.

Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: free_electron on September 21, 2013, 09:43:01 am
Patience little grashoppers. Patience. I will post updates later. November timeframe.
I got my hands on a bunch of ITT 2n2369's need to test em to see how they behave.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: alank2 on September 21, 2013, 12:22:21 pm
Patience little grashoppers. Patience. I will post updates later. November timeframe.
I got my hands on a bunch of ITT 2n2369's need to test em to see how they behave.

Awesome news!
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: BravoV on September 24, 2013, 03:22:28 am
Patience little grashoppers. Patience. I will post updates later. November timeframe.
I got my hands on a bunch of ITT 2n2369's need to test em to see how they behave.

Suggesting to add a sma to bnc converter with adjusted price of course, I'm guessing many will like it.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: Zalexei on October 01, 2013, 09:14:00 am
Dear All,

I am a newbie here. So, sorry for maybe stupid question.
Is it possible to achieve a pulse duration (FWHM) with JW pulser of sub-ns range (I need ~500ps). After reading all thread I found that the standard kit provides ~5ns.

Thank you and best regards,
Alexey
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: HackedFridgeMagnet on October 01, 2013, 09:56:25 am
You need to mention the voltage of the pulse too.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: Zalexei on October 01, 2013, 11:11:22 am
You need to mention the voltage of the pulse too.

Thanks for reminding. In fact, the peak voltage ~2-2.5V would be great. Lower voltage is not desirable. But even 200mV still acceptable.
In my application, I need to apply the generated pulses to fast laser diode (VCSEL). If the voltage will be enough I would like to connect LD directly to the pulse generator. If not. maybe SFP+ transceiver module will be needed.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: ElectroIrradiator on October 02, 2013, 07:57:03 am
It may be worth mentioning, that JW also designed a triggered version of his free running pulse generator, complete with up to 300ns variable trigger delay. Requires a +5V PSU. Check AN72 (http://www.linear.com/doclist/?dt=2&au=Jim+Williams), figure 75 on page 33.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: kcozens on October 15, 2013, 09:58:42 pm
i will try to do another run towards the end of the year. these will be kits only.

Please add my name to the list of people interested in obtaining a kit when the next batch of them is ready.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: alank2 on October 28, 2013, 11:26:50 pm
Any update on these yet? :)
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: JohnB on November 08, 2013, 09:06:50 pm
i will try to do another run towards the end of the year. these will be kits only .

Please add me to your list as well.

Thanks,
John
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: GingGangGooly on November 08, 2013, 11:22:06 pm
I would be interested in buying a kit also :)
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: mtdoc on November 08, 2013, 11:27:16 pm
Yep, me too, me too.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: simmiv on November 23, 2013, 11:16:04 pm
Yep, count me in as well for one kit..
Simmi
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: arvidj on November 24, 2013, 02:29:22 am
+1 to be added to the list.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: oe6kyg on November 27, 2013, 08:15:55 am
+1 for me to
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: ted572 on November 27, 2013, 02:04:25 pm
May I please buy one of the Pulse Generator kits (as described directly below in your Reply #477, or > PCB, Transistor, Case), what ever is easier for you, or quicker, from you also?

Thank you for considering my request, Ted572
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: free_electron on November 27, 2013, 03:28:37 pm
Wow, this seems to be picking up again...
I need to look into this. I was planning on doing another run by the end of the year, but that's not going to happen . I am too busy.

I have secured a supply of the transistors though. I have a few thousand of em now. All new old stock made by signetics. They avalanche nicely.

I will place an order for a batch of boards.
I am assuming everybody can easily get standard passive smd parts in his/ her country

I would do the kit as follows
Pcb
The linear boost chip
The switch
The diodes and high voltage caps
The battery clip
Two of the transistors , so you have a spare
The angled sma connector
The 50 ohm output resistor (we need a non inductive here)
The case

Essentially the parts that may be hard to get locally.

Then again.. The remainder is 4 resistors and 2 caps...

Or i could simply do pcb,transistor,case.

The problem is always the cost of international shipping. Flatrate boxes have gotten expensive,
That turns some people down... And the customs paperwork and other blabla...

I need to find a better way.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: alank2 on November 27, 2013, 03:33:11 pm
Thank you free electron!  I will be happy to get whatever kit you get together.  I don't mind building it.  Let me know when you have the pcbs and they are available!
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: H.O on November 27, 2013, 03:39:33 pm
Yep, me too if possible!
No problems with getting standard parts.

Thanks!
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: VintageTekFan on November 27, 2013, 03:51:33 pm
I would also be interested, in kit form.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: FTM777 on November 27, 2013, 04:02:02 pm
One set of whatever you produce for me too please.  I can source standard components.
Nick
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: kvitekp on November 27, 2013, 04:18:15 pm
pcb only, pcb + avalanche transistors, full kit -- anything works for me here.

Packaging kits is terribly time consuming. DigiKey used to do kitting/packaging but the price was a little too high to make it attractive for DIY kit suppliers. Hiring someone here in Bay Area to do kitting is cost prohibitive. So for the time being pcb + rare parts + case and DigiKey/Mouser BOM seems like the way to go.

Filling intl customs forms is another hassle. I'm trying to get myself an old dot matrix or daisy wheel printer to try printing those custom forms. Weird Stuff has some, but none were functional last time I checked.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: G7PSK on November 27, 2013, 05:13:29 pm
Get the boards sent from China, for some reason they don't seem to have customs problems, guess they just ignore them like every thing else.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: oe6kyg on November 27, 2013, 06:59:58 pm
i have no problems to get custom parts
and no problems with higher shippingcosts

Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: JohnB on November 27, 2013, 09:05:01 pm
Anything works for me as well.

Happy Thanksgiving to those in the US
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: AndersAnd on December 11, 2013, 12:44:11 am
Finally got some time to finish mine and 'hand select' the transistors for the kits. ( i ran them on the curve tracer and selected the ones that avalanched at around 40 volts. there is notable difference between the 2N2369 and 2N2369A and then manufacturers...
the ones from ST avalanche much higher .... i found a bunc of motoroils at the local junk dealer. these work fine.
So you're saying that 2N2369A is better suited than 2N2369 non-A, or is it the other way around?

And Motorola is better suited than ST?

Any manufacturing dates working better than others?

I found a source selling various NOS (new old stock) 2N2369 and 2N2369A from different manufacturers like Motorola, ST, NEC, Philips and Microsemi I think. Would Motorola be the best suited of these? Anyone tested other manufactures than Motorola and ST?
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: BravoV on December 11, 2013, 12:53:38 am
Remember, at LT app note, even Jim Williams had to sort out from many samples until he found the one that avalanched nicely.

If they're cheap, I would buy few each from every different brands.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: free_electron on December 11, 2013, 02:17:22 am
i'm stocked up on 2n2369's. i got a few thousand now :)

i'm out for now. Battling a very nasty MRSA infection.... all because of a tiny little scratch on my back.

There won't be anything coming before january.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: all_repair on December 11, 2013, 02:56:31 am
Always wanted one, but not sure you want to be troubled again to do that.  But I don't check the forum on a regular basis, likely shall miss the boat again.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: robdot on December 27, 2013, 12:16:44 pm
Hi free_electron, how are you going ?
Cheers,
Rob.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: jboard146 on January 01, 2014, 12:31:02 am
+1 kit for me
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: alank2 on January 01, 2014, 01:14:39 am
Hi free_electron, how are you going ?
Cheers,
Rob.

+1 I hope you are feeling better soon.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: GreyWoolfe on January 01, 2014, 07:01:01 am
Free_electron, get better soon and put me down for one.  Many thanks.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: Fsck on January 01, 2014, 07:35:38 am
+1 to the kit too.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: apelly on January 13, 2014, 12:52:56 am
Another +1

Hope you're well again.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: MrAureliusR on January 14, 2014, 12:38:59 am
@free_electron

Hope you're doing well. A good friend of mine had an MRSA infection in her leg, and she lost most of the muscles in one leg, and parts of her other leg as well. VERY brutal bacteria... unfortunately it can spread through bare skin to bare skin contact!!!

Really hope you're doing better...

Also, wishing for a kit :) I will be sure to check back often, I've been keeping an eye on your website as well.

On an aside to everyone, I've started a new electronics site @ http://frozenelectronics.com (http://frozenelectronics.com) ... I'm very excited and look forward to all the work associated with a video blog / writing blog.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: idpromnut on January 14, 2014, 03:09:24 am
@free_electron:

I hope the new year finds you in better health!  If/when you decide to do another run of kits, I would be in for +1.

Cheers!
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: taemun on January 16, 2014, 02:45:10 am
+1 In for a kit.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: gdewitte on January 17, 2014, 07:38:38 pm
@free_electron

I would be interested in a kit.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: Pezo on February 06, 2014, 12:32:51 pm
Hey guys, just wanted to show you my version of the pulse generator (Link to the album (http://imgur.com/a/rUgLu)).
I built a version with around 1m of RG174 for the delay line, the last picture shows the output signal on a 300MHz sampling oscilloscope.
Maybe I get the chance to measure it with a faster oscilloscope at the university.

Have a look at the album for a little more text.
(http://i.imgur.com/189zaDos.jpg) (http://imgur.com/189zaDo) (http://i.imgur.com/5Qh7eUrs.jpg) (http://imgur.com/5Qh7eUr) (http://i.imgur.com/v87VWJvs.jpg) (http://imgur.com/v87VWJv) (http://i.imgur.com/M8pi1Bfs.gif) (http://imgur.com/M8pi1Bf)
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: m100 on March 20, 2014, 04:30:05 pm
+1 on a kit
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: HackedFridgeMagnet on March 27, 2014, 06:43:18 am
So you're saying at some unknown (to me) voltage, we could get a percentage of 2n2222s to avalanche in a similar way? Would they need to be some old batch do you think or any more modern 2n2222s could avalanche?
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: T3sl4co1l on March 27, 2014, 09:46:58 am
No need for such a poorly defined transistor (seriously, the world would be a better place if everyone forgot about 2N2222 and picked 2N4401 instead ;D ), it's been my experience that 2N3904 is avalanche capable.  Typically around 90-100V, with a 4.7k B-E resistor.

Tim
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: linux-works on March 28, 2014, 02:26:13 am
I just saw this thread.  I'd like a kit, also ;)

I'm in the bay area, so if I can be of help, just ask.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: eurofox on April 12, 2014, 09:39:02 pm
+1 In for a kit MKII version.

eurofox
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: kmel on April 28, 2014, 08:03:00 pm
+1 for a MKII kit
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: joetorelli on May 10, 2014, 03:21:40 am
Hi,
New to the EEVBLOG. I just found this forum ~3wks ago. I have been reading and watching this blog forum so much my wife thinks I am cheating on her, because I been doing nothing else. Except getting majors headaches from all the reading.
Anyway are these kits still being made? I went to ebay and could not find anything. And this subject seems to have faded off. If they are still being made count me in for a calibrated kit.

Thanks
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: e-pirate on May 18, 2014, 04:51:52 pm
Hi, folks!
I'm currently designing my own version of PCB for this avalanche pulse generator. This board will be placed in aluminum box. BNC connector is a PCB vertical thought hole connector that will be soldered to the board parallel. The 50 ohm resistor mounted vertically right under signal/central wire. This is me very first design of such type generators (and frequency), so I want to know what do you think about ground polygon distribution. I separated grounds of voltage source and the output part. Any ideas how to improve?
Oh, and there is a switch on the right side of the box.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: OldTech on May 20, 2014, 06:39:35 am
@free_electron,

Hope you are well soon.

I am interested in two calibrated Picosecond Pulser MK-II units.

OldTech
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: EV on May 20, 2014, 08:23:42 am
You don't have delay line in your kit? The pulse will be very short and not flat. Look at pictures of reply 214 in this thread. There is delay line.


Hi, folks!
I'm currently designing my own version of PCB for this avalanche pulse generator. This board will be placed in aluminum box. BNC connector is a PCB vertical thought hole connector that will be soldered to the board parallel. The 50 ohm resistor mounted vertically right under signal/central wire. This is me very first design of such type generators (and frequency), so I want to know what do you think about ground polygon distribution. I separated grounds of voltage source and the output part. Any ideas how to improve?
Oh, and there is a switch on the right side of the box.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: e-pirate on May 20, 2014, 11:09:50 am
You don't have delay line in your kit? The pulse will be very short and not flat. Look at pictures of reply 214 in this thread. There is delay line.
Well, I don't know how to calculate wave guide  :-//
And I will probably combine ground polygons. I don't think there is a reason to separate them.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: han on May 20, 2014, 11:18:06 am
is there anyone ever try the impulse generator on Spectrum analyzer?
sorry if there already the answer in the 31 page before...
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: c4757p on May 20, 2014, 11:51:05 am
You don't have delay line in your kit? The pulse will be very short and not flat. Look at pictures of reply 214 in this thread. There is delay line.
Well, I don't know how to calculate wave guide  :-//

Google seems to do well for "how to calculate waveguide"...

Quote
And I will probably combine ground polygons. I don't think there is a reason to separate them.

Agreed. Unless you have a real reason to force ground currents to be separate, you're just creating extra inductance, which may or may not be a problem for you.

I like it otherwise. Nice, compact design, even though it's PTH. Perhaps you could fit some length of delay line under the battery. Alternatively, use coax!
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: free_electron on May 20, 2014, 02:54:51 pm
This project has been on the backburner a bit.

I will place an order for blank circuit boards this week.

Calibrated kits are bo longer available. I don't have access to the scope anymore.
Now, since we have a good sample spread from the original batch we know what these generators do in terms of rise time. So calibration is not really necessary

I am still in doubt what i should make available.

A) Board + 2 NOS transistors from the same batch.
B) Full kit including case

Board and transistors can be sent in a regular envelope. But , if everyone then has to start digging for all the other stuff .. Its time consuming and wont meet minimum shipping requirements from digikey or others.

Let me do a price calculation for the full kit. Parts prices may have fluctuated.

Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: alank2 on May 20, 2014, 03:18:06 pm
Awesome news!  I'd prefer one with a case, but I'll take whatever is available and don't mind sourcing parts from digikey if needed.

Please keep us posted!
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: gdewitte on May 20, 2014, 04:58:23 pm
+1 for the case kit.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: e-pirate on May 20, 2014, 06:56:26 pm
Here is a new layout with a single ground polygon. I will search through Internet how to make a waveguide and probably design another version.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: GeorgeOfTheJungle on May 20, 2014, 10:20:31 pm

I will place an order for blank circuit boards this week.


I think the name of Jim Williams ought to be on the board!

Jim Williams' avalanche (FAST) pulse generator (See Linear Technology AN47), or something like that, perhaps?

https://www.youtube.com/watch?v=3S-AS86bj4w&t=12m25s (https://www.youtube.com/watch?v=3S-AS86bj4w&t=12m25s)

Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: Chris.M on May 21, 2014, 12:43:37 am
Could you please put me down for one Full kit including case.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: H.O on May 21, 2014, 06:53:11 am
Excellent news!
I'm (still) in for a kit, whichever you decide, thanks!
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: e-pirate on May 21, 2014, 09:51:52 am
I think the name of Jim Williams ought to be on the board!
Jim Williams' avalanche (FAST) pulse generator (See Linear Technology AN47), or something like that, perhaps?
Completely agree! Just in respect to Jim.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: fpliuzzi on May 21, 2014, 11:35:28 am
Thanks for making these available again. Please put me down for one full kit including the case.
(if you decide to just make the board and two transistors available, that would be fine too)
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: linux-works on May 21, 2014, 02:36:10 pm
+1 kit for me, please.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: cyr on May 21, 2014, 05:26:42 pm
is there anyone ever try the impulse generator on Spectrum analyzer?
sorry if there already the answer in the 31 page before...

SA and scope below (with some external attenuation).
Note how the first null in the spectrum corresponds to 1 / pulse width.

Also, there is a rule of thumb that most of the frequency content of a square wave is below approximately 0.5 / rise time. That would be 2.5GHz for a 200ps edge, which looks about right.

Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: han on May 23, 2014, 03:08:01 am
is there anyone ever try the impulse generator on Spectrum analyzer?
sorry if there already the answer in the 31 page before...

SA and scope below (with some external attenuation).
Note how the first null in the spectrum corresponds to 1 / pulse width.

Also, there is a rule of thumb that most of the frequency content of a square wave is below approximately 0.5 / rise time. That would be 2.5GHz for a 200ps edge, which looks about right.



Thanks for the effort. :D
i just remember the Fourier theory when i in univ

Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: idpromnut on May 23, 2014, 09:31:58 am
If the parts + case can be sourced via digikey then i am ok with just the board and transistors. 
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: kumar on June 12, 2014, 10:58:39 am
Dear Free-electron'

I am interested in buying this generator. Can you please let me know the availablity and price?
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: HighVoltage on June 21, 2014, 12:09:01 pm
A) Board + 2 NOS transistors from the same batch.
B) Full kit including case

I would also like to get a board and transistors only, to keep your effort to a minimum.
But if you would make the full kit available, I would buy it too.
Thanks for your great support.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: arvidj on June 23, 2014, 01:47:24 am
+1 on a complete kit, +.5 on the board, transistors and a recommended parts list. We can convert the parts list to a digikey and\or mouser list and share it for those in the US.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: electronic_eel on September 12, 2014, 09:53:14 am
Any progress with the pulser board or kit?

I'm fine with just a pcb, transistor and a Digikey/Mouser parts list. But I'd also buy a kit if international shipping isn't too expensive.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: free_electron on September 12, 2014, 02:11:12 pm
Time for an update. I have received the boards (i was on vacation for the last 3 weeks.)
So i will do a pricecalc over the weekend for the kits and post details
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: linux-works on September 12, 2014, 03:36:59 pm
good news; thanks.

I'm still interested in one.

Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: idpromnut on September 12, 2014, 08:17:32 pm
Time for an update. I have received the boards (i was on vacation for the last 3 weeks.)
So i will do a pricecalc over the weekend for the kits and post details

Thank you for the update!
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: van-c on September 12, 2014, 08:56:05 pm
Yes, free_electron, thanks for the update.  I'm still interested in the kit full or partial.

--Van
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: johnh on September 13, 2014, 02:17:24 am
+1 for a kit
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: GeorgeOfTheJungle on September 17, 2014, 09:18:22 am
I'd want one too, please. Did you finally put "Jim Williams" anywhere on it?

Thank you!
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: LADmachining on September 17, 2014, 03:30:24 pm
Registering interest in a kit - will keep a close eye on this thread for updates.  ;)
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: HighVoltage on September 20, 2014, 08:54:31 am
Hello free_electron,

I am definitely still in to buy at least one kits from you, if possible, I would like to get 2 kits.
Thanks for the update.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: steverino on September 21, 2014, 04:06:02 pm
I'd be interested in a kit also...
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: MauriceS on October 02, 2014, 04:21:26 am
+1 for kit
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: VintageTekFan on October 07, 2014, 01:28:34 pm
STILL interested in 1-2 kits.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: wreeve on October 13, 2014, 10:51:43 am
Hi, this looks ideal for "calibrating" a new attenuator in an old infinium 'scope I've acquired. Datasheets suggest a rise time of <175ps will work! Has anyone in the UK got a Jim Williams board I could borrow for a day please! Bottle of wine and all postage costs covered!
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: Electro Fan on October 18, 2014, 04:18:25 am
interested in a kit with a case (or maybe an assembled unit?)
- any idea on price and availability?
Thx
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: David Hess on October 18, 2014, 04:45:27 am
Hi, this looks ideal for "calibrating" a new attenuator in an old infinium 'scope I've acquired. Datasheets suggest a rise time of <175ps will work! Has anyone in the UK got a Jim Williams board I could borrow for a day please! Bottle of wine and all postage costs covered!

If the pulse length using a charge line is long enough then it will work great.  I think you will also need some good RF attenuators though.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: Gixy on October 21, 2014, 04:15:37 pm
Hi,
+1 kit here! Looking for procedure for payment and shipping. Thanks in advance.  :-+
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: Precipice on November 12, 2014, 10:54:10 am
I'd be interested in one, too. Want to see what this 'ere 6GHz scope can actually do!
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: EV on November 17, 2014, 07:20:28 am
I'd be interested in one, too. Want to see what this 'ere 6GHz scope can actually do!

It is not fast enough for your scope. Risetime of Gaussian 6 GHz scope is about 350/6 = 58 ps and the risetime of Jim Williams pulse generator is about 170 ps.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: Precipice on November 17, 2014, 03:49:04 pm
Err, I hope it's a little quicker than 58ns...
Also, I very much doubt that this scope is Gaussian response. I think it's one of the magical downshift-frequencies and reassemble things versions, which complicates everything. (DSA70604 - the book says that it should be 65ps 10%-90% and 45ps 20-80%. It's software upgradeable to the full 20GHz, so I'd expect that all I'm seeing is a DSP filter doing a brick-wall impression to get it down to a measly 6GHz...)
(I also have a few proper analogue scopes to hand that it'd be fun to test. (Analogue from 10MHz to 1GHz, and a few points inbetween).
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: free_electron on November 17, 2014, 03:54:35 pm
i have receive about a hundred bare boards. this thing has been slipping , vacation , changing jobs , remodelling the lab..
i  need to pick this up again. lemme do some homework tonite.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: EV on November 17, 2014, 04:10:42 pm
Err, I hope it's a little quicker than 58ns...
Also, I very much doubt that this scope is Gaussian response. I think it's one of the magical downshift-frequencies and reassemble things versions, which complicates everything. (DSA70604 - the book says that it should be 65ps 10%-90% and 45ps 20-80%. It's software upgradeable to the full 20GHz, so I'd expect that all I'm seeing is a DSP filter doing a brick-wall impression to get it down to a measly 6GHz...)
(I also have a few proper analogue scopes to hand that it'd be fun to test. (Analogue from 10MHz to 1GHz, and a few points inbetween).

Sorry, my mistake! It is ps not ns. I have edited my text. However Jim Williams pulse generators risetime is only about 170 ps. For analogue (non sampling) scopes it is fast enough.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: dr.diesel on November 17, 2014, 04:18:36 pm
changing jobs

Thanks!

What is new job?  Please fill us in.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: G7PSK on November 17, 2014, 04:28:40 pm
I think the new job was mentioned on the Amp-hour a while back. something to do with Tesla I believe.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: VintageTekFan on November 17, 2014, 04:30:39 pm
this thing has been slipping , vacation , changing jobs , remodelling the lab..

I hope the job change was for the better!
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: AwArD_RzD on November 19, 2014, 01:05:13 pm
Count me in for a kit !
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: msraya on November 19, 2014, 01:27:49 pm
I'm interested also in one unit.
Please send me some information when you can..

I have a Agilent MSO9404 Scope wandered here in the lab with some 4GHz bandwidth that I want to test  :-+

Thank You for the good job!

Regards
Manuel
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: free_electron on November 19, 2014, 03:52:44 pm
changing jobs

Thanks!

What is new job?  Please fill us in.
i am now lead PCB designer at Tesla motors.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: alank2 on November 19, 2014, 04:00:25 pm
i am now lead PCB designer at Tesla motors.

Excellent!  :)
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: Gixy on November 19, 2014, 09:27:18 pm
Hi Vince,
I confirm my interest for one kit, I just bought your book on SMT to improve my skills on these little things  :). I just had a PM on my profile.
I'm an old reader as I already had your first book on Electronic with VB!
Thanks a lot and wish you all the best in your new job. Great cars!
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: VintageTekFan on November 19, 2014, 09:46:28 pm
i am now lead PCB designer at Tesla motors.

Awesome  :-+ :-+
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: Dave on November 21, 2014, 07:39:49 am
i am now lead PCB designer at Tesla motors.
Nice! :-+
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: dr.diesel on November 21, 2014, 12:08:39 pm
i am now lead PCB designer at Tesla motors.


 :-+


We all know Tesla is on the cutting edge and has lots to protect, but hopefully you'll be able to share some of the coolness with us. 
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: etl17 on November 25, 2014, 11:49:16 pm
+1 for a kit (if it's not too late!)....
Title: single pulse from Jim Williams Pulse Generator
Post by: croyleje on November 30, 2014, 10:46:46 pm
Hi Everyone,
I have built a pulser similar to the original design the one i build is from AN61 Triggered 250PS Rise Time Pulse.  The reason I went with this design is so I could have a manual trigger single pulse but I have tried using a simple momentary push button but the switch bounce is giving me issues and when I tried putting some debounce in the circuit I believe it was the cap that then caused issues.  Looking for a simple idea on how I could trigger a single very fast pulse for testing my scopes and other things in the future?  No real reason I only want to be able to trigger the single pulse just like that idea more then the repetitive pulse of the original.
Thanks Jason

http://cds.linear.com/docs/en/application-note/an61fa.pdf (http://cds.linear.com/docs/en/application-note/an61fa.pdf)

couldn't post whole pdf here is link page 21 and 22
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: vasilistzo on December 04, 2014, 02:19:15 pm
+1 kit please for me .
I ve been reading all the posts since 2012 for the last few hours.

Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: motocoder on December 05, 2014, 02:47:32 am
i have receive about a hundred bare boards. this thing has been slipping , vacation , changing jobs , remodelling the lab..
i  need to pick this up again. lemme do some homework tonite.

If it's not too late, please mark me down for one kit.

Congrats on your new job, too.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: AlessandroAU on December 19, 2014, 03:39:44 am
Does any know what changes I could try make to make the top of my pulse flatter?
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: marshallh on December 19, 2014, 04:01:31 am
Get a scope with more bandwidth?

That's a pretty good result for a 1Meg input with I assume a feedthru termination
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: Jay_Diddy_B on December 19, 2014, 04:05:03 am
Does any know what changes I could try make to make the top of my pulse flatter?

Can you post your schematic and a photograph of your circuit?

And have a look a the pdf document attached to this post:

https://www.eevblog.com/forum/projects/transmission-line-avalanche-pulse-generator/msg185639/#msg185639 (https://www.eevblog.com/forum/projects/transmission-line-avalanche-pulse-generator/msg185639/#msg185639)

Regards,

Jay_Diddy_B
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: AlessandroAU on December 19, 2014, 04:19:59 am
Does any know what changes I could try make to make the top of my pulse flatter?

Can you post your schematic and a photograph of your circuit?

And have a look a the pdf document attached to this post:

https://www.eevblog.com/forum/projects/transmission-line-avalanche-pulse-generator/msg185639/#msg185639 (https://www.eevblog.com/forum/projects/transmission-line-avalanche-pulse-generator/msg185639/#msg185639)

Regards,

Jay_Diddy_B


The pulse generator uses a 2n2369 with a 1pf tank cap and 1m of semi rigid coax.

Are the waves in the top of the pulse caused by internal reflections past the 50ohm feedthrough terminator?
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: Jay_Diddy_B on December 19, 2014, 01:17:37 pm
Hi,
Some of what you are seeing is the scopes performance. The top of the screen says 1G sample per second and 60 points. I assume that there are only 60 samples for the information displayed. The scope is joining the dots between the samples. I don't know if the Rigol scope has an option to highlight the data points or turn off the vectors.

If you turn on a second channel, the sample rate, per channel will drop to 500 Ms/s, and see if this changes your waveform.

This scope picture from my TDS744A converted to a TDS784A has 100 G samples per second, equivalent time, so there is 100 time more information used build the waveform. This requires a repetitive waveform to acquire all the samples.



(https://www.eevblog.com/forum/testgear/conversion-of-500mhz-tds744a-to-1ghz-tds784a/?action=dlattach;attach=124648;image)

Regards,

Jay_Diddy_B
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: Gixy on February 04, 2015, 01:02:07 pm
No news from Vincent concerning kits' availability? He seems to be very busy testing DEX  :-/O
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: silicon_ghost on April 08, 2015, 03:14:32 am
On the slim chance I can still get one...

+1 kit for me please
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: moocow on July 22, 2015, 04:43:26 pm
Probably a long shot, but any way to get one of these still?
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: DarthBubba on August 05, 2015, 05:30:22 pm
Once again, late to the dance...    :palm:

@Free_Electron, any pulse generator kits still available?  I'm here in the 'States so mailing/customs would not be a problem.   :-+

PM/email also sent to you.

Thanks,
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: dadler on August 06, 2015, 08:35:58 pm
Can someone just post a gerber or put the layout on OSHPark?

I searched and couldn't find the layout anywhere.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: HighVoltage on August 07, 2015, 07:51:55 am
Can someone just post a gerber or put the layout on OSHPark?

I searched and couldn't find the layout anywhere.
+1
I am also really interested in that oine.
Thanks to anyone that can help with this.
Title: Testing on Tek 2467/65
Post by: Electro Fan on October 08, 2015, 01:46:10 am
Anyone out there with a Jim Williams type pulse generator and either a Tek 2467 or a Tek 2465 that would be up for checking to see what rise time, fall time, width, and frequency measurements you get on your scope?  Thx, EF
Title: Re: Testing on Tek 2467/65
Post by: mtdoc on October 08, 2015, 10:02:34 am
Anyone out there with a Jim Williams type pulse generator and either a Tek 2467 or a Tek 2465 that would be up for checking to see what rise time, fall time, width, and frequency measurements you get on your scope?  Thx, EF

Can't do it now, but I should be able to this weekend.
Title: Re: Testing on Tek 2467/65
Post by: Electro Fan on October 08, 2015, 09:41:37 pm
Anyone out there with a Jim Williams type pulse generator and either a Tek 2467 or a Tek 2465 that would be up for checking to see what rise time, fall time, width, and frequency measurements you get on your scope?  Thx, EF

Can't do it now, but I should be able to this weekend.

Thanks - I found that when you use the auto measurement function the scope takes over and gives you a measurement (I got 570ps for rise time) but it wants to change the waveform display to it's preferred format.

I found that using the X10 mag and the positioning controls I could get a better looking (more relevant/insightful) waveform.  I used the variable voltage feature to line up (what I thought was) the bottom and top on 0% and 100% and then used the 10% and 90% markings to position the cursors which displayed the measure rise timed as being 520ps (0.52ns). 

In the specs for the 2467B Tektronix gives a rise time of 875ps.  The rate Tektronix spec of 400MHz corresponds to a period of 2.5ns.  Using the formula of BW = 0.35 / Tr gives a rise time of the same 875ps as specified by Tektronix. 

I have tried inputting signals higher than 400MHz into the 2467B and found that the frequency counter will hang in there until well above 600MHz - which leads me to believe that other parts of the scope can exceed the specs by up to 50%.  Using the 50% factor would indicate that perhaps the scope can really measure better than the 875ps for rise time - possibly to 583ps or maybe better.  Let's say the scope can actually measure to 500ps.  When we get a reading such as 520ps is that measuring the rise time of the Jim Williams-type pulse generator (which I think might have been designed to achieve a 270ps rise time) or is the scope displaying a combination of what the pulse generator is doing plus what the scope is capable of doing?  (Maybe what the scope displays is simply it's own best performance which is masking what the faster pulse generator is doing?)  Not sure if I phrased this right....  Thanks   
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: Howardlong on October 08, 2015, 10:42:34 pm
Is that really the rise time? From the trace, I'm not sure that the vertical ever gets the chance to reach the peak before it returns.

You can extend the pulse with a foot of RG174 open ended stub in parallel with the cap.

I found the Y goes a bit non linear too, even adjusting the Y pos up and down alters the pulse shape somewhat.

(http://i34.photobucket.com/albums/d123/photobucket391/6550e624f28eeb7644a92e865bd4d145_zpsud4eqznb.jpg)
(this pulse generator plus 20dB pad measures 340ps on a 1GHz Agilent 7000 and 360ps on s 600MHz Agilent 54831D running in equivalent time.)

(http://i34.photobucket.com/albums/d123/photobucket391/b681452aaf40637998740e9b407ff7ee_zpsuupykxug.jpg)

(http://i34.photobucket.com/albums/d123/photobucket391/f1be30571b154c8522259ec338f2820f_zps8qmwxxae.jpg)
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: Electro Fan on October 09, 2015, 12:12:46 am
Howard, What would keep the pulse from reaching it's peak and shorten the time before the fall?

(It does look somewhat similar to the shape shown in the video.... but maybe I'm missing something....)

Thanks, EF

Updates:

A quick scan for others who have gone down similar paths found this:
http://www.i9t.net/fast-pulse/fast-pulse.html (http://www.i9t.net/fast-pulse/fast-pulse.html)

- seems like on EEV and elsewhere some JW pulses look kind of pointy and some have flat tops....  :-//

Also found this - seems like the author made one version (MK-I) that was substantially per J. Williams and a second version (MK-II) that modified the original design to add "a stripline charge capacitor to lengthen the pulse so there would be a nice plateau at the top"
http://www.siliconvalleygarage.com/projects/picosecond-pulser.html (http://www.siliconvalleygarage.com/projects/picosecond-pulser.html)

The plot thickens.  Found this:
http://webpages.charter.net/dawill/tmoranwms/Elec_Pulse.html (http://webpages.charter.net/dawill/tmoranwms/Elec_Pulse.html)
"Two designs are given by Jim Williams of Linear Technology: one in AN47, High Speed Techniques, pp.93-95, and more of a "luxury model" in AN94, The Taming Of The Slew. Both of these are available for download from Linear Technology."
http://www.linear.com/designtools/app_notes.php (http://www.linear.com/designtools/app_notes.php)

Found this:
http://cds.linear.com/docs/en/application-note/an47fa.pdf (http://cds.linear.com/docs/en/application-note/an47fa.pdf)
which included a scope trace shown below (that looks kind of "pointy")
... still looking for the "luxury model" in AN94...

Getting closer:
http://cds.linear.com/docs/en/application-note/an94f.pdf (http://cds.linear.com/docs/en/application-note/an94f.pdf)
- I think the answer (or part of it) is in here but I need some help from the many much more knowledgeable EEVers to glean it from this document.

In the meantime, I found one more item that gives a sense for Jim Williams - fourth image below.  He was prolific and had a sense of humor, for sure  :-+ :-+

Think I found it:
'The 10pF capacitor supplies the initial pulse response, with the charge lines prolonged discharge contributing the pulse body. The 40" charge line length forms an output pulse width about 12ns in duration'

Pulse Width Set with Charge Lines

Figure 8. Variable Delay Triggers a Subnanosecond Rise Time Pulse Generator. Charge Line at Q5’s Collector Determines
»10 Nanosecond Output Width. Output Pulse Occurance is Settable from Before-to-After Trigger Output
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: Jay_Diddy_B on October 09, 2015, 02:01:22 am
Hi,

The there are two kinds of Jim Williams pulse generators. The first kind has a capacitor attached to the collector of the avalanche transistor. This type produces the peaky waveform.

In the second kind, the capacitor is replaced by a transmission line. The transmission is either a piece of coax or it can be placed in the PCB artwork.

During the time Free_Electron was developing the project in this thread, I was working on my version which used a transmission line. The final version can be found in this post:

https://www.eevblog.com/forum/projects/transmission-line-avalanche-pulse-generator/msg606142/#msg606142 (https://www.eevblog.com/forum/projects/transmission-line-avalanche-pulse-generator/msg606142/#msg606142)

I spent a long time getting to this performance.

(https://www.eevblog.com/forum/projects/transmission-line-avalanche-pulse-generator/?action=dlattach;attach=135387;image)

At some point free_electron modified his design to incorporate the transmission line:

https://www.eevblog.com/forum/projects/transmission-line-avalanche-pulse-generator/msg185694/#msg185694 (https://www.eevblog.com/forum/projects/transmission-line-avalanche-pulse-generator/msg185694/#msg185694)

With the transmission line, the pulse width is twice the electrical length of the line.

Regards,

Jay_Diddy_B
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: Electro Fan on October 09, 2015, 02:14:15 am
Ok, I think we just contributed to moving toward a doubling of the installed base.

Some EEVers who thought they already had a Jim Williams Avalanche Pulse Generator now might need at least one more:  :-+ :-+
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: Electro Fan on October 09, 2015, 02:43:50 am
Jay_Diddy_B,

I saw in the specs there was an 11801 (maybe an A version?) and maybe B and C versions with specs that were in the range of 28-7ps rise times?!  Amazing.

If a scope had a rise time spec of 30ps and a pulse generator had a rise time of 100ps, would the scope show the rise time to be 100ps, or would it add it's own "latency?" and show the measured rise time to be 130ps?  Thanks, EF
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: Jay_Diddy_B on October 09, 2015, 02:57:29 am
Hi,

The scope is being used with a SD24 sampling head. This has a rise time of 17.5ps (20 GHz of BW).

http://w140.com/tekwiki/wiki/SD-24 (http://w140.com/tekwiki/wiki/SD-24)


If you have a 100ps rise time generator and 100ps rise time scope the displayed rise time is

Rise time displayed = sqrt (100ps2 + 100p2) = 141ps

working backwards

I have a displayed rise time of 91ps and a scope rise time of 17.5ps

generator rise time = sqrt (91ps2 - 17.5ps2) = 89ps

since my scope is 5 times faster than the generator it gives an accurate reading of the rise time.

Similar to measure a scope rise time you need a signal that is 4 or 5 times faster than the scope.

How fast is 90ps ?

The speed of light is 3 x 108 ms-1

The speed of propagation on FR4 board is about 0.66 times the speed of light so 2 x 108 ms-1

Multiply by the rise time 90 x 10-12

And you get the signal would travel

2 X108 x 90 x 10-12 = 0.018 metres, 18 mm (3/4 of an inch)

So you can visualize a wave.

Regards,

Jay_Diddy_B
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: Electro Fan on October 09, 2015, 04:18:05 am
Thanks for the formulas - I was able to follow your first example

Rise time displayed = sqrt (100ps2 + 100p2) = 141ps

and your second example

generator rise time = sqrt (91ps2 - 17.5ps2) = 89ps

but I'm still lost somewhere.

What would you think would be the displayed rise time for a scope with a rise time of 875ps and a generator with a rise time of 270ps?  (These are supposedly the specs on my scope and generator).  If I use the formula in your first example above I get about 916ps - but when doing measurements with my scope the scope is reporting 570ps when using the Auto rise time measurement and 520ps when using the manual cursors.  Not to mention, I can't quite get my head around how a scope could ever show a generator rise time or any rise time faster than it's inherent rise time (ie, 875ps for the 2467B).

Thanks
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: T3sl4co1l on October 09, 2015, 04:42:38 am
The exact relation depends upon the type of response the scope has.  For example, the old tube scopes (which usually used distributed amplifiers, which cut off very sharply above their passband) will give a different result to the more gradual passband typical of DSOs.  Which will, in turn, be different depending on how they are peaked -- a lot of the crappier Teks of recent history had this (a ringing step response!!), while the ideal for a scope is a Bessel or approximated Gaussian filter response.

The result is more sensitive to response because an ideal spike has constant amplitude harmonics, while a step waveform has harmonics that drop off inversely.  It's not an ideal way to measure rise time -- since, after all, rise time is defined as the step rise!

Tim
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: Electro Fan on October 10, 2015, 05:01:22 am
The exact relation depends upon the type of response the scope has.  For example, the old tube scopes (which usually used distributed amplifiers, which cut off very sharply above their passband) will give a different result to the more gradual passband typical of DSOs.  Which will, in turn, be different depending on how they are peaked -- a lot of the crappier Teks of recent history had this (a ringing step response!!), while the ideal for a scope is a Bessel or approximated Gaussian filter response.

The result is more sensitive to response because an ideal spike has constant amplitude harmonics, while a step waveform has harmonics that drop off inversely.  It's not an ideal way to measure rise time -- since, after all, rise time is defined as the step rise!

Tim

Tim, that's interesting but obviously the 2467B isn't a tube scope (assuming you are talking about vacuum tubes).

Also, as discussed above, it appears that Jim Williams designed (at least) a couple different pulse generators; the first produced a somewhat "peaky" pulse and the second produced a longer lasting pulse with a "pulse body".

Given that his first and perhaps most famous version produced a "peaky" pulse and that he published a fair amount of data regarding his design and testing it appears that it is very possible to measure such a waveform.

In any event, I'm still trying to figure out why the 2467B shows a rise time of 520-570 picoseconds and how it does that when it's own rise time specification is 875 picoseconds.  EF

Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: T3sl4co1l on October 10, 2015, 09:15:35 am
That was for flavor, not for direct application.

SS analog scopes can fall inbetween; they usually tried to have ample bandwidth in earlier stages (1GHz+), limiting it only where necessary (usually at the vertical driver).  This gives a more gradual (e.g. lower order Bessel) response.  I don't know how common it was to use distributed amps in SS scopes, but if one uses them, expect the same reasoning and tradeoff.

My point was also that a pulse is a different signal, that follows different rules.  A very short (say 100ps) pulse is completely over and done before the output has began to rise; how can you justify the assumptions concerning risetime when such action is present?  A proper step comes, and stays there, until the output has stabilized, it's not darting up and down.

You can't apply the BW = 0.35 / t_r or risetime addition formulas, because those were derived under one set of assumptions, which aren't true here.

The FWHA of a pulse is the most common measure; this I think tends to be more well-behaved, though I don't know if it follows the same rules.

Tim
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: Electro Fan on October 10, 2015, 06:36:09 pm
That was for flavor, not for direct application.

SS analog scopes can fall inbetween; they usually tried to have ample bandwidth in earlier stages (1GHz+), limiting it only where necessary (usually at the vertical driver).  This gives a more gradual (e.g. lower order Bessel) response.  I don't know how common it was to use distributed amps in SS scopes, but if one uses them, expect the same reasoning and tradeoff.

My point was also that a pulse is a different signal, that follows different rules.  A very short (say 100ps) pulse is completely over and done before the output has began to rise; how can you justify the assumptions concerning risetime when such action is present?  A proper step comes, and stays there, until the output has stabilized, it's not darting up and down.

You can't apply the BW = 0.35 / t_r or risetime addition formulas, because those were derived under one set of assumptions, which aren't true here.

The FWHA of a pulse is the most common measure; this I think tends to be more well-behaved, though I don't know if it follows the same rules.

Tim

Thanks for the flavor.

If a rocket goes perfectly straight up 10 miles in 2 seconds but then completely stalls and falls nearly straight back to Earth, we can still say the rocket went up 10 miles in 2 seconds.

I think it's a generally accepted practice to measure rise time independent of the width of a pulse.

From Wikipedia:
"rise time is the time taken by a signal to change from a specified low value to a specified high value. Typically, in analog electronics, these values are 10% and 90% of the step height" - no reference to the duration of the step or pulse width.

Likewise, Dave's video on the Jim Williams pulse generator discusses and measures rise time with a very similarly shaped ("peaky") pulse.  Whether it's 0.35 or 0.4, or somewhere in that vicinity, I think what Dave says at roughly 2:30 in the video is that the formula can be used to calculate the bandwidth of the scope and it seems by math that would imply it can also be used to calculate the rise time of the pulse.

I also noted the reference to Full Width Half Amplitude and I think I understand your suggestion that the nature of some waves makes them more "well-behaved" than others - but at the end of the day we either get a rise time measurement or we don't.  If we do, it might be an accurate measurement or it might not.  Fair.

With all that in mind, back to the original question:  how/why does a 400 MHz oscilloscope with a rise time spec of 875ps measure and display a rise time of 570ps or 520ps on the (admittedly peaky) pulse?  The only thing I can guess (beside the fact that the rise time created by the pulse generator is at least 570ps, and probably faster) is that the scope significantly exceeds it's bandwidth and rise time specifications.  Or maybe it's a bogus measurement - I tend not to think so but it would be good to see some other tests results. 

Still hoping to see others with a Jim Williams type generator and a 2467 or 2465 make some rise time measurements and report the findings.

If others get a similar measurement and if we have reason to believe the 246X is showing accurate measurements, then I'd like to go back to Jay_Diddy_B's formulas and see if we can derive how much of the rise time was contributed by the scope and how much was contributed by the pulse generator.  The goal is to measure the rise time on the generator and a secondary objective is to determine the rise time capability of the scope.  (Obviously, other JW generator designs may produce other results.) 

At the end of the day, I'm just trying to figure out how to measure something through analysis because I don't have high enough performance test equipment to directly measure and display the answer.  It's a challenge and a learning process.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: T3sl4co1l on October 10, 2015, 11:43:12 pm
The answer is simple: it has absolutely nothing to do with the instrument, but the signal.  Perform the measurement correctly (consistently -- measuring the step response with a step!) and you will observe the rated spec of the instrument.

Quite frankly, Dave is most likely following the same rules of thumb as anyone else.  I expect he hasn't, for example, worked out the impulse response and dispersion relations of typical filter types, and derived the rules independently and accurately -- he's much too lazy (= good) of an engineer to do that!  Moreover, given his lack of enthusiasm for higher math(s), he probably doesn't know how to work that out (or very quickly), anyway.  (No offense, if you're reading, Dave -- I hope I'm not underestimating your knowledge level here.)

And to be fair, I don't know either, but, I'm not afraid of working a little calculus to figure things out, and if I were charged with finding it, I feel confident I could.

I guess if you don't have a solid footing in filter and signals theory, and Fourier analysis, there isn't much I can quickly tell you that will convey this, other than to continue to assert that I am right (that the signals are different, and incomparable by the same rule of thumb, which depends upon gross assumptions).  Are you incapable of taking that in confidence?  :-//

As for physical analogies, we can work with that.  Acceleration to velocity is a single pole filter (namely, an ideal integrator), and acceleration with drag is a single pole filter at some frequency (where the cutoff frequency is given by mass and drag coefficient).  Suppose we label acceleration as input, and velocity as output.

The pulse is not simply a "rocket going up", but a proper impulse, such as a rocket engine which burns out much faster than the drag time constant, or, say, the blast wave from an explosion.  The rocket instantaneously accelerates (it's able to, because this is a single pole system; aside from the few scopes with deflection plates tied directly to the input transmission line, this is not representative of scopes, though), then gradually slows down at a rate determined by that time constant.

The risetime is therefore zero, because it can accelerate instantly from a stop, limited only by the rate of the impulse itself.  FWHA is proportional to one fall time.

Whereas a step applies variable acceleration, so as to achieve a certain steady-state value (velocity, in this case).  If we apply a constant acceleration, it will eventually balance against the drag force, so the total acceleration goes to zero, and the velocity stabilizes to a constant.  The 10-90% risetime is something like 2.2 time constants (assuming the usual exponential single pole response).

If it were a two pole filter of some type (like critical damping), the impulse response won't rise instantly, and the result will be a hump that's going up and down completely on its own, with no force from the impulse as it goes.  Whereas the step has to continue dragging through the whole range, like a tsunami coming in.

Oh, it may also help just to realize the relationship between ideal step and impulse responses: impulse is the derivative of step.  The entire rising edge of the step is the entire width of the impulse.  If the 'corners' are symmetrical (such as a Gaussian passband has), 10-90% points on the step correspond to 10-10% points on the impulse!  (Or something like that.)  The 10-90% points on the impulse are only the beginning of the toe of the entire step.

Tim
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: mtdoc on October 11, 2015, 12:28:27 am
I'm still trying to figure out why the 2467B shows a rise time of 520-570 picoseconds and how it does that when it's own rise time specification is 875 picoseconds.

Why do you think the rise time of your scope is 875 psecs?  The Tek 2400 series scopes routinely have much higher bandwidth than their nominal specification.

My 2467 has a measured -3dB bandwidth of almost 450 Mhz  - far above it's nominal 350MHz and in line with the rise times seen in the pics below.  First pic is my JW pulser, second is waveform without coax attached. Last is with 18 inch length of coax to give a flat top.

Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: Electro Fan on October 11, 2015, 02:27:02 am
I'm still trying to figure out why the 2467B shows a rise time of 520-570 picoseconds and how it does that when it's own rise time specification is 875 picoseconds.

Why do you think the rise time of your scope is 875 psecs?  The Tek 2400 series scopes routinely have much higher bandwidth than their nominal specification.

My 2467 has a measured -3dB bandwidth of almost 450 Mhz  - far above it's nominal 350MHz and in line with the rise times seen in the pics below.  First pic is my JW pulser, second is waveform without coax attached. Last is with 18 inch length of coax to give a flat top.

Thanks for sharing your test results.

It's not that I "think" the rise time specification for the Tektronix 2467B is 875ps, it's that 875ps is the published specification for the Tektronix 2467B - as shown in the image below.

To be clear, I hypothesized more than once earlier in this thread that the actual performance of the 2467B exceeds it's specification, maybe by 50%, or more.  Your measurement with the 350MHz version of the scope indicates that the scope does in fact exceed it's specification.  This is a plausible reason for the test results.  Thanks again for sharing your test results.

Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: Electro Fan on October 11, 2015, 02:33:15 am
The answer is simple: it has absolutely nothing to do with the instrument, but the signal.  Perform the measurement correctly (consistently -- measuring the step response with a step!) and you will observe the rated spec of the instrument.

Quite frankly, Dave is most likely following the same rules of thumb as anyone else.  I expect he hasn't, for example, worked out the impulse response and dispersion relations of typical filter types, and derived the rules independently and accurately -- he's much too lazy (= good) of an engineer to do that!  Moreover, given his lack of enthusiasm for higher math(s), he probably doesn't know how to work that out (or very quickly), anyway.  (No offense, if you're reading, Dave -- I hope I'm not underestimating your knowledge level here.)

And to be fair, I don't know either, but, I'm not afraid of working a little calculus to figure things out, and if I were charged with finding it, I feel confident I could.

I guess if you don't have a solid footing in filter and signals theory, and Fourier analysis, there isn't much I can quickly tell you that will convey this, other than to continue to assert that I am right (that the signals are different, and incomparable by the same rule of thumb, which depends upon gross assumptions).  Are you incapable of taking that in confidence?  :-//

As for physical analogies, we can work with that.  Acceleration to velocity is a single pole filter (namely, an ideal integrator), and acceleration with drag is a single pole filter at some frequency (where the cutoff frequency is given by mass and drag coefficient).  Suppose we label acceleration as input, and velocity as output.

The pulse is not simply a "rocket going up", but a proper impulse, such as a rocket engine which burns out much faster than the drag time constant, or, say, the blast wave from an explosion.  The rocket instantaneously accelerates (it's able to, because this is a single pole system; aside from the few scopes with deflection plates tied directly to the input transmission line, this is not representative of scopes, though), then gradually slows down at a rate determined by that time constant.

The risetime is therefore zero, because it can accelerate instantly from a stop, limited only by the rate of the impulse itself.  FWHA is proportional to one fall time.

Whereas a step applies variable acceleration, so as to achieve a certain steady-state value (velocity, in this case).  If we apply a constant acceleration, it will eventually balance against the drag force, so the total acceleration goes to zero, and the velocity stabilizes to a constant.  The 10-90% risetime is something like 2.2 time constants (assuming the usual exponential single pole response).

If it were a two pole filter of some type (like critical damping), the impulse response won't rise instantly, and the result will be a hump that's going up and down completely on its own, with no force from the impulse as it goes.  Whereas the step has to continue dragging through the whole range, like a tsunami coming in.

Oh, it may also help just to realize the relationship between ideal step and impulse responses: impulse is the derivative of step.  The entire rising edge of the step is the entire width of the impulse.  If the 'corners' are symmetrical (such as a Gaussian passband has), 10-90% points on the step correspond to 10-10% points on the impulse!  (Or something like that.)  The 10-90% points on the impulse are only the beginning of the toe of the entire step.

Tim

So you are saying the scope measurements (shown with my generator and scope, and with mtdoc's generator and scope) are or are not accurate measurements?
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: mtdoc on October 11, 2015, 02:37:36 am

It's not that I "think" the rise time specification for the Tektronix 2467B is 875ps, it's that 875ps is the published specification for the Tektronix 2467B - as shown in the image below.


Ok thanks for clarifying. I would look at the 875ps in the specs as just another way of them stating the nominal bandwidth - since 875 ps corresponds to a calculated bandwidth of 400 MHz.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: Electro Fan on October 11, 2015, 02:52:03 am

It's not that I "think" the rise time specification for the Tektronix 2467B is 875ps, it's that 875ps is the published specification for the Tektronix 2467B - as shown in the image below.


Ok thanks for clarifying. I would look at the 875ps in the specs as just another way of them stating the nominal bandwidth - since 875 ps corresponds to a calculated bandwidth of 400 MHz.

Right - there is little to no doubt in my mind that a normally functioning Tek 246X scope will exceed it's published specs; I think these scopes might exceed their specs by a significant margin.  So, I think the rise time you saw on the 350 MHz version is reasonably consistent with the rise time on the 400 MHz version.  Of course we don't know is how similar our JW pulsers are - which might account for some of the difference in our test results.  Regardless, I am pretty sure that JW pulsers can produce a rise time that is faster than what the 246X can keep up with.  So I think what we are seeing is the mostly the rise time threshold of the 246X and to a lesser extent the rise time performance of the JW pulser.  It's interesting to see that the rise time measurements on your "peaky" version and your "flat top" version are not all that much different.  Which leads me to believe that if in fact the scope is capable of measuring the more conventional flat top version there is not much reason to doubt it's ability to measure the peaky version - but Tim might have some reason to think otherwise. :)
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: mtdoc on October 11, 2015, 03:06:00 am
Of course we don't know is how similar our JW pulsers are - which might account for some of the difference in our test results.  Regardless, I am pretty sure that JW pulsers can produce a rise time that is faster than what the 246X can keep up with.  So I think what we are seeing is the mostly the rise time threshold of the 246X and to a lesser extent the rise time performance of the JW pulser. 

Yes, exactly.  My 2467 is the fastest scope I have. (nominal bandwidth of 350MHz compared to your 400 MHz).  When I've tested my JWP on my other scopes (hacked Rigol DS2072, Teks 2236, 475, 465b and BK 60MHz scope) the measured rise time has been in each case very close to what I would expect based on the measured -3dB bandwidth of those scopes.  I just wish I had a super fast scope to see what the rise time of my JWP really is.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: Jay_Diddy_B on October 11, 2015, 03:09:38 am
Hi,

Here is a picture from my Tektronix 2467B.

I adjusted the variable gain and position to put the top and bottom of the waveform on the 0% and 100% lines respectively. I then adjusted the cursors to intersect the 10% and 90% lines.

(https://www.eevblog.com/forum/blog/eevblog-306-jim-williams-pulse-generator/?action=dlattach;attach=175624;image)

Regards,

Jay_Diddy_B
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: mtdoc on October 11, 2015, 03:37:58 am
Hi,

Here is a picture from my Tektronix 2467B.

I adjusted the variable gain and position to put the top and bottom of the waveform on the 0% and 100% lines respectively. I then adjusted the cursors to intersect the 10% and 90% lines.


Thanks for posting the pic and exposing the Faux Pas in my measurement technique!  I need to pay closer attention next time  :o . I just checked mine again with the waveform properly aligned and the measurement doesn't change much :  0.75--->0.72 ns (or so ..probably +/- 0.01 ns error by eyeball).   

Nice wave form!  Not sure why your 2467b should have a slower rise time than my 2467....
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: Electro Fan on October 11, 2015, 03:42:03 am
Hi,

Here is a picture from my Tektronix 2467B.

I adjusted the variable gain and position to put the top and bottom of the waveform on the 0% and 100% lines respectively. I then adjusted the cursors to intersect the 10% and 90% lines.

(https://www.eevblog.com/forum/blog/eevblog-306-jim-williams-pulse-generator/?action=dlattach;attach=175624;image)

Regards,

Jay_Diddy_B

Thanks

So, given that your pulse generator operates at (an incredibly fast!) 89ps, what you are largely showing is largely the rise time of the 2467B - yes?

All good - I'm just down to trying to figure out how I got 0.57 to 0.52ns....?
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: Howardlong on October 11, 2015, 07:28:06 am
EF:

Simply that because the pulse width is so short, well before your scope's vertical could even reach the real voltage peak, the pulse generator was already heading south. By extending the pulse width, it gives time for the scope to reach the actual voltage peak.

Therefore, I'd say you weren't measuring 90% of the peak voltage, just 90% of how far the vertical made it before the input had dropped back.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: T3sl4co1l on October 11, 2015, 08:57:40 am

So you are saying the scope measurements (shown with my generator and scope, and with mtdoc's generator and scope) are or are not accurate measurements?

They are what they are, of that there can be no doubt.  But the impulse response is not the step response, and so cannot be used to measure it.

Tim
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: Electro Fan on October 11, 2015, 09:27:30 am
EF:

Simply that because the pulse width is so short, well before your scope's vertical could even reach the real voltage peak, the pulse generator was already heading south. By extending the pulse width, it gives time for the scope to reach the actual voltage peak.

Therefore, I'd say you weren't measuring 90% of the peak voltage, just 90% of how far the vertical made it before the input had dropped back.

Ok, that seems understandable and plausible - but how does it explain the mtdoc's results posted below?  Seems like mtdoc's 350MHz scope caught the peaky pulse (and the wider pulse didn't yield a much different result).  So it would seem that a 400MHz scope should have also caught the peaky pulse.... unless there is something notably faster about my generator, which would be difficult thing to determine at the rate I'm going.... :)
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: T3sl4co1l on October 11, 2015, 11:19:34 am
Like I said, these things need not be consistent, because the response to different generators isn't.

Tim
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: Jay_Diddy_B on October 11, 2015, 11:45:44 am
Hi,

Like Tim said, I think the pulse from your pulse generator is too short. Here is a simulation of a filter being tested with a short pulse and a long pulse:

(https://www.eevblog.com/forum/blog/eevblog-306-jim-williams-pulse-generator/?action=dlattach;attach=175681;image)

You would think the short pulse indicates higher BW, but the filters are identical.

Try adding about 18 inches of 50 Ohm coax in parallel with the capacitor in your pulse generator. This will length the pulse to about 4ns.


Regards,

Jay_Diddy_B
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: mtdoc on October 11, 2015, 05:59:48 pm
I just picked up on eBay one of these Tek scope demo boards (http://www.ebay.com/itm/191712059881). It includes a fast, <200 ps pulse output for checking scope rise time. It will be interesting to see what it looks like on my 2467.

FWIW my best offer of $30 was accepted though I specifically said I did not need the manual included (it's online). As of now, it looks liike there is one left.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: Electro Fan on October 11, 2015, 08:01:49 pm
Hi,

Like Tim said, I think the pulse from your pulse generator is too short. Here is a simulation of a filter being tested with a short pulse and a long pulse:

You would think the short pulse indicates higher BW, but the filters are identical.

Try adding about 18 inches of 50 Ohm coax in parallel with the capacitor in your pulse generator. This will length the pulse to about 4ns.


Regards,

Jay_Diddy_B

Jay_Diddy_B, Thanks.

Ok, these questions are going to officially get me labeled as a complete rookie.... :-[

(I didn't build the pulse generator - I'm just using it.  Except for the transistor pretty much everything on the board looks like SMD; so it's kind of small stuff and I'd prefer not to wreck an otherwise nice pulse generator. :scared:)

I see a 1M Ohm resistor (connected to the Collector?) and a 10k resistor (connected to the Base) near the transistor; instead of one 50 Ohm resistor connected to the Emitter I see two 50 Ohm resistors next to each other - not sure why there are two there.

There are only two capacitors that I see near the transistor (and also reasonably near the BNC connector) - one that is considerably larger and further from the transistor and another that is relatively smaller and a little closer to the transistor.  The one that is larger is pretty much the same physical size as two other capacitors also on the board - all three measure about 420nF.  The one that is smaller and closer to the transistor and BNC is difficult to measure; sometimes I measured it as being about 3-5pF and sometimes around 60pf??  Any chance it is this smaller capacitor that is the right capacitor to connect to the coax?

Assuming I have the right capacitor (the one that measures 3-5pF and occasionally 60pF), any chance you could post a diagram showing where to add the 18" of 50 Ohm coax (from where to where)?

Thanks

Howard, I saw your suggestion:  "You can extend the pulse with a foot of RG174 open ended stub in parallel with the cap."  I wasn't sure if "open ended stub" meant just solder the length of the coax onto one side (either side?) of the capacitor and let the other end of the coax dangle free, or something else.  Any clarifications or suggestions on how not to mess up a working generator would be very welcome.  Thx! EF
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: Howardlong on October 11, 2015, 08:54:33 pm
Coax shield to ground plane, inner to the collector, directly across the cap, but keep the exposed coax as short as possible, a mm or two, best done under an illuminated magnifier at least.

Open ended stub means the far end of the coax is left open rather than shorted (or anything else), mine's about 15" or so.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: EV on October 14, 2015, 07:51:47 am
Here are 2 pictures about rise time of my 2465B scope.

In first picture the pulse is from Tektronix type 284 pulse generator. Its rise time is faster than 35 ps.

In second picture the pulse is from JW pulse generator (MK-2 rise time tester Nr 32). I have used it with 10 dB attenuator. Its rise time is 190 ps.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: Electro Fan on October 14, 2015, 08:29:57 pm
Here are 2 pictures about rise time of my 2465B scope.

In first picture the pulse is from Tektronix type 284 pulse generator. Its rise time is faster than 35 ps.

In second picture the pulse is from JW pulse generator (MK-2 rise time tester Nr 32). I have used it with 10 dB attenuator. Its rise time is 190 ps.

Very cool - Thanks for posting.

This would seem to confirm that the rise time of the scope is roughly as specified (875ps) and that Jay_Diddy_B's formulas are working :), and that your JW Mk-2 is very fast and that your 284 is blazingly fast.   :-+ :-+
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: Electro Fan on October 16, 2015, 11:49:42 pm
A progress report.

First, thanks to everyone here for the ongoing education  :-+

A bit of extra thanks to mtdoc for mentioning the Tek demo board earlier in this thread.  It happens to have a <200ps rise time signal which provides a much wider (~20ns) pulse than the very "peaky" pulse produced by the JW pulser I've been trying to measure.  As noted in the photo below the Tek demo board produces a rise time that is measured by the 2467B as being 720ps - which seems reasonably consistent with others results shown in this thread.

A second thing/further thanks to EEVers.  This forum is really, really helpful.  The other thing that is helpful is to just keep plugging (haha) with more experiments and gaining more experience.  When I received the demo board I tried powering it with a 9V battery but that had it's limitations.  So, next I tried using the leads from the plug-on cap for the battery as attachment points for the alligator clip leads on my DC power supply.  For some reason it wasn't working - turns out that while I recognize the larger 9V battery terminal as the minus and the smaller battery terminal as the plus, when you look at the cap the connector sizes are of course the opposite (inside the cap the larger connector goes over the smaller plus terminal on the battery, and vice versa on the other connector/terminal).  So by habit I clipped them backwards, and .... no power on the board.  Duh.

Between trial and error and EEVblog it's a doable and very enjoyable learning journey  :)
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: Jay_Diddy_B on October 17, 2015, 01:20:23 am
Hi,

Can you reverse engineer this section of the Tektronix demo board? Or put a high resolution picture of this part of the board on the forum?

Thanks !!

Jay_Diddy_B
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: Electro Fan on October 17, 2015, 01:59:33 am
Reverse engineer?  I can hardly forward engineer. :-DD

(It's a nice product - I'd recommend one for purchase.  Since it's in the public domain I think it's A-OK to show it / look at it.)
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: mtdoc on October 17, 2015, 02:08:38 am
Hi,

Can you reverse engineer this section of the Tektronix demo board? Or put a high resolution picture of this part of the board on the forum?

Thanks !!

Jay_Diddy_B

Manual with schematics is available HERE (http://www.mhzelectronics.com/ebay/manuals/tektronix_quickstart_8_dpo_demonstration_board_manual.pdf). Pulse generator schematic on A-11.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: Electro Fan on October 17, 2015, 03:05:30 am
Question:

On the test board the spec says it can run between 6 and 12 Volts and it wants a 5 Watt transformer.  I calculated that 9 Volts would support 0.555 Amps (and stay within 5 Watts).  It turns out that at 9 Volts the board draws less than 0.4 Amps.  Given that the spec says the range is 6 to 12 Volts, is there any reason to think that supplying the board with more voltage (beyond 9V but less than 12V) and lowering the current, or supplying less voltage (below 9V but at least 6V) and raising the current would somehow enable the board to produce a cleaner pulse and/or a faster rise time?  Or within the range of 6-12 Volts the pulse and rise time performance will not be impacted?
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: Electro Fan on October 18, 2015, 09:44:08 am
Some more measurements and observations.

I found a SMA to BNC connector which allowed me to directly attach the Tek demo board to the scope (with no cable).

With the automeasure function the scope shows 850ps.  With 30" of RG223 the automeasure shows the same 850ps as with the directly attached board.  I tried with a 5' RG174 cable and the automeasure shows 960ps.

With the directly attached board using the cursors the scope shows 740ps.  I think part of this is due to my uncertainty of where to line up the 0% and 100% lines.  I can get a pretty good line on 0% by tracing backward on the waveform well before it begins to ascend, but I'm not so sure about what constitutes the 100% peak.  Even so, the automeasure seems to provide significantly more conservative (slower) results.

Conclusions:

1. The automeasure is consistently (always) slower (more accurate?) than the cursor measurements.
2. With the directly attached board and the 30" of RG223 I think the automeasure is bumping up against the threshold of the scope's rise time.
3. 5' of RG174 is enough to add some delay.
4. If you want to get a more impressive rise time use the cursors instead of the automeasure :)
5. YMMV
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: Electro Fan on October 22, 2015, 06:32:02 pm
Still trying to measure the peaky JW type pulse gen.  Here is an attempt with a Tek 7A19 (500MHz).  The timebase readouts are correct - the Voltage readout is not correct.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: mtdoc on October 24, 2015, 06:59:10 am
Finally got around to playng with the Tek Demo board fast rise output.  Fastest rise time I get is with board directly connected to my 2467 (50 ohm input).  Rise time of 0.78 - 0.79 ns is a bit slower than what i get with my JWP.
Title: Pulse Generator on the Grid
Post by: notadave on October 24, 2015, 06:13:52 pm
I build my own version that is powered by an unregulated 12V AC wall adapter (just a Transformer).
I got it to work after I increased the capacities in my charge ladder from 220nF to 22uF. To my surprise the capacity had a great impact on the voltage. Especially the lower capacitors have to be bigger than I thought.
By using 6x 22uF capacitors in only 3 steps I got a peak voltage that is so much higher than the breakdown voltage, that the breakdown occurs, but so low that it will happen only once per grid cycle.
It is good enough to measure a cable of 9ft, or less if it is shorted. Since I do not use a delay line I get a normal discharge shape.
I designed a version with a 0.2m coplanar PCB 50 Ohm line that is not yet build.

My 2N3904 breaks at 112V.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: max-bit on October 27, 2015, 06:51:01 pm
OK
To dispel doubts
Based post :
https://www.eevblog.com/forum/buysellwanted/pulse-generator-kits-or-ready-to-use/ (https://www.eevblog.com/forum/buysellwanted/pulse-generator-kits-or-ready-to-use/)
and my topic:
https://www.eevblog.com/forum/projects/new-version-pulse-generator-(based-jim-williams-pulse-gen)/msg775033/#msg775033 (https://www.eevblog.com/forum/projects/new-version-pulse-generator-(based-jim-williams-pulse-gen)/msg775033/#msg775033)
used oscilloscope:
LeCroy LC584AL 1 GHz 8GS/s (rise time ~330-350ps)
Pulse the load 50Om
(http://www.rflab.pl/projekty/Pulse_gen/LeCroy/D013.jpg)
(http://www.rflab.pl/projekty/Pulse_gen/LeCroy/D008.BMP)
Pulse the load 1MOm
(http://www.rflab.pl/projekty/Pulse_gen/LeCroy/D006.BMP)
jitter trigger pulse
(http://www.rflab.pl/projekty/Pulse_gen/LeCroy/D014.BMP)
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: max-bit on October 27, 2015, 08:47:18 pm
An interesting generator with a small rise time 35ps
Basen on IC ONET8501
http://www.ti.com/lit/ds/symlink/onet8501p.pdf (http://www.ti.com/lit/ds/symlink/onet8501p.pdf)
Link project
https://www.kickstarter.com/projects/1855991221/10-ghz-usb-oscilloscope (https://www.kickstarter.com/projects/1855991221/10-ghz-usb-oscilloscope)
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: LY1 on January 15, 2017, 05:40:27 pm
Where I can bay fast pulse generator?
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: luisprata on April 01, 2017, 08:21:31 am
Hi,

Anybody knows if I can use the board bellow confiured as 60MHz clock generator with 200ps rise time as a pulse generator?
https://www.digikey.com/products/en?keywords=LMK61PDEVM (https://www.digikey.com/products/en?keywords=LMK61PDEVM)

Thank you.
Luis.
Title: Re: EEVblog #306 - Jim Williams Pulse Generator
Post by: David Hess on April 01, 2017, 11:16:44 am
Anybody knows if I can use the board bellow confiured as 60MHz clock generator with 200ps rise time as a pulse generator?

You could but:

1. It is not 200ps even in the worst case.  The specification is for a 20/80 transition time.
2. There are no specifications or even graphs showing the output transient response.  Texas Instruments does not even provide a simplified schematic of the output structures.
3. The output is not ground referred.

So you would just have to buy one and test it.