EEVblog #306 - Jim Williams Pulse Generator

[sdscotto]

Guess I should have checked here instead of waiting by the mailbox.   Any estimate on when the next batch goes out?

[EV]

I got the kits today, Thanks!

[G7PSK]

Joy oh joy and jubilations the kit arrived today. Thank you, now comes the fun!

[EV]

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.

[BravoV]

EV, is that extra 20cm cable was intentional ? How about direct SMA to BNC socket result ?

[EV]

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.

[EV]

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.

[jpb]

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.

[jpb]

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.

[robrenz]

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?

[jpb]

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

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.

[fmaimon]

Any news on the shipping and data of the serial number 50? I'm very curious of the results...

[BravoV]

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. 

[e-pirate]

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.

[free_electron]

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...

[notsob]

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

[nack]

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.

[jpb]

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 

[AlfBaz]

Received my kits today, thanks Vincent 

[free_electron]

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.

[enz]

I also received mine yesterday, thanks.

Martin

[Christe4nM]

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.

[e-pirate]

Is it a good idea to mount SMD trim cap instead of 2 pF on the collector, I have some 1.4-4 pF?

[fmaimon]

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?

[free_electron]

I will post the final cal screenshots this weekend. Last batch goes out the door tomorrow. Fmaimon was in the last batch.(last week)