Author Topic: EEVblog #306 - Jim Williams Pulse Generator  (Read 245782 times)

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Offline robrenz

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Re: EEVblog #306 - Jim Williams Pulse Generator
« Reply #125 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 ::)

Offline prenato

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Re: EEVblog #306 - Jim Williams Pulse Generator
« Reply #126 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:)
Paulo
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Offline free_electron

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Re: EEVblog #306 - Jim Williams Pulse Generator
« Reply #127 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.
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Offline robrenz

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Re: EEVblog #306 - Jim Williams Pulse Generator
« Reply #128 on: October 15, 2012, 05:58:50 pm »
Mine showed up in todays mail  :).  Thanks free_electron for the cable and the suprise  :P

Offline free_electron

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Re: EEVblog #306 - Jim Williams Pulse Generator
« Reply #129 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.

« Last Edit: October 28, 2012, 04:18:45 pm by free_electron »
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Offline esharmon

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Re: EEVblog #306 - Jim Williams Pulse Generator
« Reply #130 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
 

Offline carpin

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Re: EEVblog #306 - Jim Williams Pulse Generator
« Reply #131 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

« Last Edit: October 17, 2012, 10:39:17 pm by carpin »
 

Offline free_electron

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Re: EEVblog #306 - Jim Williams Pulse Generator
« Reply #132 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.
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Offline notsob

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Re: EEVblog #306 - Jim Williams Pulse Generator
« Reply #133 on: October 24, 2012, 04:30:36 pm »
arrived in wednesday's mail, those poor freight pigeons must be worn out.
 

Offline notsob

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Re: EEVblog #306 - Jim Williams Pulse Generator
« Reply #134 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.
 

Offline free_electron

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Re: EEVblog #306 - Jim Williams Pulse Generator
« Reply #135 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]
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Offline chavotronic

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Re: EEVblog #306 - Jim Williams Pulse Generator
« Reply #136 on: October 28, 2012, 06:05:33 pm »
Hi Free Electron, Did you receive my message?

Best Regards,

David :)
 

Offline HackedFridgeMagnet

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Re: EEVblog #306 - Jim Williams Pulse Generator
« Reply #137 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?
 

Offline notsob

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Re: EEVblog #306 - Jim Williams Pulse Generator
« Reply #138 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
 

Offline chavotronic

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Re: EEVblog #306 - Jim Williams Pulse Generator
« Reply #139 on: November 01, 2012, 02:41:34 pm »
Okay, seems like noone is getting my personal messages. :'(
Anyone has 2 PCBs left for me?

 

Offline free_electron

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Re: EEVblog #306 - Jim Williams Pulse Generator
« Reply #140 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 ?
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Offline chavotronic

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Re: EEVblog #306 - Jim Williams Pulse Generator
« Reply #141 on: November 01, 2012, 04:48:55 pm »
2 kits please parts incl. :) :)
 

Offline HackedFridgeMagnet

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Re: EEVblog #306 - Jim Williams Pulse Generator
« Reply #142 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?





 

Offline free_electron

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Re: EEVblog #306 - Jim Williams Pulse Generator
« Reply #143 on: November 10, 2012, 05:37:41 pm »
will post this today.
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Offline spelunker

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Re: EEVblog #306 - Jim Williams Pulse Generator
« Reply #144 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
 

Offline branadic

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Re: EEVblog #306 - Jim Williams Pulse Generator
« Reply #145 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.
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Offline HackedFridgeMagnet

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Re: EEVblog #306 - Jim Williams Pulse Generator
« Reply #146 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?
« Last Edit: January 01, 2013, 05:41:28 am by HackedFridgeMagnet »
 

Offline HackedFridgeMagnet

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Re: EEVblog #306 - Jim Williams Pulse Generator
« Reply #147 on: January 01, 2013, 05:36:05 am »
More pics.
 

Offline carpin

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Re: EEVblog #306 - Jim Williams Pulse Generator
« Reply #148 on: January 02, 2013, 01:10:23 pm »
Here two schematic drawings that I have.
 

Offline free_electron

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Re: EEVblog #306 - Jim Williams Pulse Generator
« Reply #149 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.
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