Author Topic: Yet another fast edge pulse generator  (Read 27752 times)

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Offline rx8pilot

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Re: Yet another fast edge pulse generator
« Reply #275 on: November 03, 2017, 12:09:22 PM »
That is pretty cool.....especially for a tiny $75 device.

Glad I got one.
Thank you EEVBlog for all the support in the Keysight Test to Impress Giveaway voting!
 

Offline texaspyro

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Re: Yet another fast edge pulse generator
« Reply #276 on: November 23, 2017, 01:45:24 PM »
I got in my pulser a couple of days ago.  A couple of new measurements for the table:

Tek TDS3034 (non-A) up-hacked to TDS3054:  560 ps / 715 MHz
Tek THS730A: 1.4 ns /  285 Mhz

Used 0.4 / rise time for the calculation.
 

Offline Jwalling

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Re: Yet another fast edge pulse generator
« Reply #277 on: November 27, 2017, 11:30:55 PM »
Got mine a week or so ago. Build quality is excellent and it works great!

Results:
Agilent   54832D   1000         331   
Tektronix   TDS784A   1000         270   
Tektronix   TDS3052     500           620   
Tektronix   TDS694C   3000         106   
Agilent   54855A   6000         68
Jay

System error. Strike any user to continue.
 

Offline HighVoltage

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Re: Yet another fast edge pulse generator
« Reply #278 on: November 28, 2017, 02:59:45 AM »
Got mine a week or so ago. Build quality is excellent and it works great!

Results:
Agilent   54832D   1000         331   
Tektronix   TDS784A   1000         270   
Tektronix   TDS3052     500           620   
Tektronix   TDS694C   3000         106   
Agilent   54855A   6000         68

I had to look up the Agilent model number 54855A.
It is a real-time scope with a bandwidth of  7 GHz?
Nice result of 68 ps!


There are 3 kinds of people in this world, those who can count and those who can not.
 

Offline grumpydoc

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Re: Yet another fast edge pulse generator
« Reply #279 on: November 29, 2017, 12:12:46 AM »
Keysight DSO1024A



2.48ns seems borderline slow for a 200MHz 'scope - I guess it comes in as 0.5/BW and the DSO1024A drops to 500Ms/s when all channels are in use so it probably has a pretty tight filter on the front end.
 

Offline Howardlong

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Re: Yet another fast edge pulse generator
« Reply #280 on: November 29, 2017, 12:19:45 AM »
Keysight DSO1024A



2.48ns seems borderline slow for a 200MHz 'scope - I guess it comes in as 0.5/BW and the DSO1024A drops to 500Ms/s when all channels are in use so it probably has a pretty tight filter on the front end.

Is the scope 50-ohm terminated?
 

Offline grumpydoc

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Re: Yet another fast edge pulse generator
« Reply #281 on: November 29, 2017, 12:33:31 AM »
Keysight DSO1024A

2.48ns seems borderline slow for a 200MHz 'scope - I guess it comes in as 0.5/BW and the DSO1024A drops to 500Ms/s when all channels are in use so it probably has a pretty tight filter on the front end.

Is the scope 50-ohm terminated?
No and I suspect that might have something to do with the response.

Disappointingly though for a 200MHz 'scope the DSO1024A has no built in 50 ohm termination.

However the path from Leo's pulser to the front end is so short that I suspect putting any external termination in will make things worse, not better.

I have a home made 50 ohm pass-through somewhere - I might dig it out and see if my suspicion is correct.
 

Offline grumpydoc

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Re: Yet another fast edge pulse generator
« Reply #282 on: November 29, 2017, 08:43:40 AM »
I have a home made 50 ohm pass-through somewhere - I might dig it out.....

OK, so, makes a huge difference! 1.24ns

Trying to get my head around the interaction of the termination resistance and the input capacitance of the 'scope (18pf, so about 8.8 ohms at a GHz).



Fair bit of ringing though, similar with a T piece and the usual crappy 50 ohm terminator.



The data sheet gives 1.8ns but that is just a calculated figure (using 0.35/BW)
 

Offline WastelandTek

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Re: Yet another fast edge pulse generator
« Reply #283 on: December 02, 2017, 03:52:22 PM »
hey Leo

Are you thinking the design iterations are pretty much done now?
I'm new here, but I tend to be pretty gregarious, so if I'm out of my lane please call me out.
 

Offline Leo Bodnar

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Re: Yet another fast edge pulse generator
« Reply #284 on: December 02, 2017, 08:44:54 PM »
hey Leo
Are you thinking the design iterations are pretty much done now?
Hiya,
Pretty much so. 
Pulser performance went beyond what I originally wanted it to do. It even has an LED now.
Cheers
Leo

Offline WastelandTek

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Re: Yet another fast edge pulse generator
« Reply #285 on: December 03, 2017, 04:33:59 AM »
hey Leo
Are you thinking the design iterations are pretty much done now?
Hiya,
Pretty much so. 
Pulser performance went beyond what I originally wanted it to do. It even has an LED now.
Cheers
Leo

right on, I think I am deserving a Christmas present  ;)
I'm new here, but I tend to be pretty gregarious, so if I'm out of my lane please call me out.
 

Offline FriedLogic

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Re: Yet another fast edge pulse generator
« Reply #286 on: December 03, 2017, 09:53:32 AM »
It's not that the performance of the BNC connector is unacceptable in itself, it's that the whole idea behind a fast pulser is to test fast hardware.  Having to use a BNC-to-SMA adapter with a fast DUT is certainly worse than having to use an SMA-to-BNC adapter with a slower DUT.
I accept your reasoning but I had problems with people not being able to find suitable USB cable locally.
Looks like I'd have to make and stock SMA version as well at some point.
Leo

Has anyone come across any readily available good and cheap SMA(f) - BNC(m) adaptors? (not surplus expensive ones, but cheap when bought new)

The main problem with most of the cheap BNC adaptors and plugs that I've seen is that they are missing the raised flange around the end of the ground connection on the plug, so don't connect well with the socket. The plating on a lot of them does not help much either.

I've sometimes bent the contacts out a little so that they connect better, but that's certainly not ideal.
 

Offline Leo Bodnar

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Re: Yet another fast edge pulse generator
« Reply #287 on: December 03, 2017, 10:00:07 AM »
Has anyone come across any readily available good and cheap SMA(f) - BNC(m) adaptors? (not surplus expensive ones, but cheap when bought new)

The main problem with most of the cheap BNC adaptors and plugs that I've seen is that they are missing the raised flange around the end of the ground connection on the plug, so don't connect well with the socket. The plating on a lot of them does not help much either.

I've sometimes bent the contacts out a little so that they connect better, but that's certainly not ideal.
I use these https://www.digikey.co.uk/products/en?keywords=314-1184-ND when testing the pulsers.
« Last Edit: December 03, 2017, 10:02:13 AM by Leo Bodnar »
 

Online Berni

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Re: Yet another fast edge pulse generator
« Reply #288 on: December 04, 2017, 05:26:28 PM »
I would buy another one of these if a SMA version becomes available.

I would guess that most people would still prefer it to be BNC since that makes it a great scope speed testing tool. But with the sort of speeds this thing is going at makes the rated few GHz frequency on a BNC seam a bit lacking. While SMA on the other hand goes in to the low 10s of GHz and is pretty widespread so i'm sure anyone that dabbled with RF has some SMA cables and adapters laying around.

You can probably make the PCB compatible with both SMA and BNC, then just solder BNCs on most of them while leaving a few without connectors. That way you can make small quick runs of the SMA version, but if there is not enough interest you can still go ahead and put BNCs on those too. Guess it would make sense to make the SMA version a few dollars more expensive for the extra trouble.
 

Offline HighVoltage

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Re: Yet another fast edge pulse generator
« Reply #289 on: December 04, 2017, 09:22:22 PM »
I would buy another one of these if a SMA version becomes available.

Same here.
if you make the SMA version available, I will take one too.
There are 3 kinds of people in this world, those who can count and those who can not.
 

Offline WastelandTek

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Re: Yet another fast edge pulse generator
« Reply #290 on: December 05, 2017, 12:44:05 PM »
OK Leo, order 23042 in

Thank you and have a good holiday!
I'm new here, but I tend to be pretty gregarious, so if I'm out of my lane please call me out.
 

Offline EEngo

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Re: Yet another fast edge pulse generator
« Reply #291 on: December 06, 2017, 07:55:03 AM »
Leo, thank you very much, my order arrived today. :-+ :box:

the Lecroy DDA125 (aka LC684, 1.5GHz analog bandwith) was mentioned in your very first post with 295ps  :-//, here are some additional measurements (see attachments):

Channel A: 248 ps
Channel B: 245 ps
Channel C: 249 ps
Channel D: 241 ps

perhaps someone with access could update the list, some more scopes will hopefully follow tomorrow (HP54616B, HM2008,Rigol MSO2202)
 

Offline Leo Bodnar

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Re: Yet another fast edge pulse generator
« Reply #292 on: December 06, 2017, 08:15:48 AM »
OK Leo, order 23042 in
Thank you and have a good holiday!
Thank you for your order, it has shipped today.

Leo, thank you very much, my order arrived today.

the Lecroy DDA125 (aka LC684, 1.5GHz analog bandwith) was mentioned in your very first post with 295ps  :-//, here are some additional measurements (see attachments):

Channel A: 248ps
...
My pleasure!  That was the older pulser model based on ADCMP***, its design has changed since then.  Amplitude increased too.
Leo

Offline Converter

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Re: Yet another fast edge pulse generator
« Reply #293 on: December 07, 2017, 03:29:27 AM »
Hello, Leo,
Order Number is: 23079
Please send the latest version of the design.

Sergey.
 

Offline EEngo

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Re: Yet another fast edge pulse generator
« Reply #294 on: December 07, 2017, 09:13:59 AM »
another measurements (see attachments):

HP 54616B (500 MHz): 540 ps  :-+
Hameg HM2008 (200 MHz): 1,5 ns  :palm:
Rigol MSO2202 (200 MHz): 1,3 ns  ;)

cool project, thanks leo!  :-+

 

Offline Leo Bodnar

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Re: Yet another fast edge pulse generator
« Reply #295 on: December 08, 2017, 05:46:42 AM »
cool project, thanks leo!  :-+
You are welcome!
Thanks to everyone who ordered one.
All the orders have been shipped - usually within one working day from placing them.
Leo

Offline H.O

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Re: Yet another fast edge pulse generator
« Reply #296 on: December 08, 2017, 06:27:52 AM »
The list has been updated, 94 entries this far.
 

Offline grumpydoc

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Re: Yet another fast edge pulse generator
« Reply #297 on: December 08, 2017, 07:52:36 PM »
The list has been updated, 94 entries this far.

The DSO1024A entry needs correcting to 1240ps. It turns out that termination does matter after all** :)


** In other news: Pope is Catholic etc.
 

Offline richnormand

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Re: Yet another fast edge pulse generator
« Reply #298 on: December 09, 2017, 03:43:42 AM »
Nice work H.O.
For the very fast systems (sampling scopes et al) you might have to note if the pulser is the early or the late version.
I would think that 40ps compared to 50ps  Tr will make a difference on a system with a 20ps risetime and such...

 

Offline H.O

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Re: Yet another fast edge pulse generator
« Reply #299 on: December 09, 2017, 04:08:15 AM »
I'm sure it does but I can only put in the list what the user reports here, I unfortunately don't know which user has which version.

I usually have to Google scope sample rate and look at the attached photos/screenshots to figure out if internal/external/no termination has been used. When I don't know I leave that entry blank.

And, as you can see, for the very fast system the formula fails so the list is far from perfect.

I'll fix the DS1204A entry on the next round.
 


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