Author Topic: Yet another fast edge pulse generator  (Read 169891 times)

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Offline rx8pilot

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Re: Yet another fast edge pulse generator
« Reply #400 on: October 11, 2018, 12:36:40 am »
Just a heads-up for anyone who has missed this - BNC versions are in stock for immediate shipment.

I have modified a few units to take external trigger input instead of on-board TCXO.  This allows feeding external LVCMOS (1.0v to 3.3v) trigger input into SMA connector.  Trigger frequency can be from 1MHz to about 200MHz.

Thanks
Leo

http://www.leobodnar.com/shop/index.php?main_page=product_info&cPath=124&products_id=295

Leo - have you seen the Picotest product? They are selling a USB powered pulse gen for $3,500!!!
https://www.picotest.com/products_J2151A.html
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Offline kado

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Re: Yet another fast edge pulse generator
« Reply #401 on: October 11, 2018, 04:52:39 am »
rx8pilot: unfortunately $98 for shipping to EU country ?!

Is anybody willing to buy two units for me and send them private to me?

Karsten


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Online Berni

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Re: Yet another fast edge pulse generator
« Reply #402 on: October 11, 2018, 05:13:03 am »

Leo - have you seen the Picotest product? They are selling a USB powered pulse gen for $3,500!!!
https://www.picotest.com/products_J2151A.html

Wow it might even be a similar design because the specs look pretty close to Leos pulse generator.
 

Offline Leo BodnarTopic starter

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Re: Yet another fast edge pulse generator
« Reply #403 on: October 11, 2018, 09:05:33 am »
Press Release
Quote
Contact Information: Picotest.com Steve Sandler - Steve@picotest.com (877) 914-7426
June 6, 2018 Phoenix, AZ: Picotest.com, a leader in high resolution test and measurement equipment, has released a new, low cost, pocket-sized, fast edge signal generator and TDR in one convenient package. “Such a high speed, precise TDR/TDT has never before been available in this portable form, requiring only a USB power source, and at this price point,” according to Steve Sandler, Picotest CEO.

What can you say? "At this price point" is technically correct.

Leo - have you seen the Picotest product? They are selling a USB powered pulse gen for $3,500!!!
https://www.picotest.com/products_J2151A.html

 

Offline Hydron

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Re: Yet another fast edge pulse generator
« Reply #404 on: October 11, 2018, 09:21:50 am »
Just a heads-up for anyone who has missed this - BNC versions are in stock for immediate shipment.

I have modified a few units to take external trigger input instead of on-board TCXO.  This allows feeding external LVCMOS (1.0v to 3.3v) trigger input into SMA connector.  Trigger frequency can be from 1MHz to about 200MHz.

Thanks
Leo

http://www.leobodnar.com/shop/index.php?main_page=product_info&cPath=124&products_id=295
Leo, is this a new PCB design, or just a mod to a few existing units? (i.e. will it be a feature going forward?)
Also, with the external input, is it possible to change back to the 10MHz TCXO, or is it a permanent change? Most of the time I'd want to use the on-board oscillator, but an external input would be useful sometimes too (for me, more so than a trigger output).
 

Offline Leo BodnarTopic starter

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Re: Yet another fast edge pulse generator
« Reply #405 on: October 11, 2018, 09:28:21 am »
It's a permanent mod on existing PCB.  It might make it into the design in the future but I don't have anything imminent planned.
Leo
I have modified a few units to take external trigger input instead of on-board TCXO.
Leo, is this a new PCB design, or just a mod to a few existing units? (i.e. will it be a feature going forward?)
Also, with the external input, is it possible to change back to the 10MHz TCXO, or is it a permanent change? Most of the time I'd want to use the on-board oscillator, but an external input would be useful sometimes too (for me, more so than a trigger output).
 

Offline LapTop006

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Re: Yet another fast edge pulse generator
« Reply #406 on: October 11, 2018, 11:28:35 am »
Figured I might as well join in the crowd and share my screenshot. 2.5Ghz optioned MSO6004X, best result 114ps rise (*way* more scope than I need, but handy for some stuff I'm doing).

This is one of the 2.92mm versions as that's all Leo had in stock at the time, so there's also an SMA to BNC on it as well (yes I know I shouldn't do that to a 2.92), IIRC it tested out below 30ps.
 

Offline Converter

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Re: Yet another fast edge pulse generator
« Reply #407 on: October 11, 2018, 11:55:43 am »
Press Release
Quote
Contact Information: Picotest.com Steve Sandler - Steve@picotest.com (877) 914-7426
June 6, 2018 Phoenix, AZ: Picotest.com, a leader in high resolution test and measurement equipment, has released a new, low cost, pocket-sized, fast edge signal generator and TDR in one convenient package. “Such a high speed, precise TDR/TDT has never before been available in this portable form, requiring only a USB power source, and at this price point,” according to Steve Sandler, Picotest CEO.

What can you say? "At this price point" is technically correct.

Leo - have you seen the Picotest product? They are selling a USB powered pulse gen for $3,500!!!
https://www.picotest.com/products_J2151A.html
Their game of 10,000% profitability will be abruptly finished at the moment when the Chinese start copying it from 5% profitability of the price components :)
 

Offline electrolust

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Re: Yet another fast edge pulse generator
« Reply #408 on: October 11, 2018, 04:51:26 pm »
Why all the hate? geez. For one, picotest's is significantly faster than Leo's original (but on par with latest version). No over/undershoot and lots of features. Encapsulated as a dongle.

The cost of electronics is never the BOM cost. For the number of units they will probably sell, I doubt they'll break even on the R&D and the mold cost for the enclosure.

I'm just saying, they put thought and effort into it. They have salaries to pay. It's not fair to pick on them. It's totally different when it's a commercial product vs a one-man effort. You don't have to hate on the pico product to appreciate Leo's.

That said, I think I am going to pick up another Bodnar unit.  :)
« Last Edit: October 11, 2018, 05:01:04 pm by electrolust »
 
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Offline electrolust

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Re: Yet another fast edge pulse generator
« Reply #409 on: October 11, 2018, 04:52:11 pm »
Is there any hope to see Leo's edge on a UXR?
 

Offline electrolust

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Re: Yet another fast edge pulse generator
« Reply #410 on: October 11, 2018, 04:56:33 pm »
Leo, your sales page (linked from post#1) says both "sold out" and "in stock". Which is it please.

(not being critical here, just want to point out this is an example of costs that go into a commercial offering of the sort that picotest has. they have "people" to pay that manage the storefront. they could not tolerate this kind of mistake, even though it is a small one. they have to keep a polished corporate image. etc.)
 

Offline Mr. Scram

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Re: Yet another fast edge pulse generator
« Reply #411 on: October 11, 2018, 04:58:24 pm »
Why all the hate? geez. For one, picotest's is significantly faster than Leo's original (but on par with latest version). No over/undershoot and lots of features. Encapsulated as a dongle.

The cost of electronics is never the BOM cost. For the number of units they will probably sell, I doubt they'll break even on the R&D and the mold cost for the enclosure.

I'm just saying, they put thought and effort into it. They have salaries to pay. It's not fair to pick on them. It's totally different when it's a commercial product vs a one-man effort.

That said, I think I am going to pick up another Bodnar unit.  :)
With low volume specialist products the BOM cost quickly loses relevance.
 

Offline Leo BodnarTopic starter

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Re: Yet another fast edge pulse generator
« Reply #412 on: October 11, 2018, 05:11:34 pm »
Leo, your sales page (linked from post#1) says both "sold out" and "in stock". Which is it please.
Sorry, SMA and 2.92mm versions are out of stock and waiting to be made next week. 
The "sold out but in stock" bug is a known feature of the website - it is powered by Zen-cart so a bit transcendental sometimes.
Good criticism is very welcome!
Leo
 

Offline Leo BodnarTopic starter

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Re: Yet another fast edge pulse generator
« Reply #413 on: October 11, 2018, 05:22:37 pm »
I know that our website looks a bit shabby but we are a small company of four and a half people with no time for polishing our image.

If I were to buy a commercial pulser [in the absence of mine] I'd probably go for http://www.hyperlabsinc.com/HL9201.aspx from Agoston Agoston - the man who designed a lot of Tek sampling scope heads.
 

Offline KE5FX

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Re: Yet another fast edge pulse generator
« Reply #414 on: October 11, 2018, 10:46:03 pm »
Leo - have you seen the Picotest product? They are selling a USB powered pulse gen for $3,500!!!
https://www.picotest.com/products_J2151A.html

That comes with a directional coupler, though, doesn't it?
 

Offline rx8pilot

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Re: Yet another fast edge pulse generator
« Reply #415 on: October 11, 2018, 11:12:18 pm »
Leo - have you seen the Picotest product? They are selling a USB powered pulse gen for $3,500!!!
https://www.picotest.com/products_J2151A.html

That comes with a directional coupler, though, doesn't it?

Indeed, it does. Curious how the kit breaks down in price.
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Online Berni

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Re: Yet another fast edge pulse generator
« Reply #416 on: October 12, 2018, 05:21:41 am »
Its actually just a resistive power divider by the looks of it since those tend to be used for TDR while network analyzers use directional couplers.

Still that being said a 10GHz resistive power divider is still not very cheap. I built my own before that seamed to work well to 3GHz (Thats as far as the network analyzer could go), but i would imagine its a lot more difficult to diy a power splitter for 10 GHz.

I had a plan to try making one DIY and testing it for >10GHz but i never got around to it and my 22GHz spectrum analyzer needs some repair (Proabobly old caps in the PSU)
 

Offline Leo BodnarTopic starter

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Re: Yet another fast edge pulse generator
« Reply #417 on: October 12, 2018, 07:54:58 pm »
Directional coupler edge over power splitter is its lower insertion loss but the downside is, typically, lower bandwidth.  Or risetime degradation, depending on how you look at it.  Most classic TDR heads I have seen use power splitters. 
Do you want me to look into making one available?

 

Offline exe

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Re: Yet another fast edge pulse generator
« Reply #418 on: October 12, 2018, 08:02:02 pm »
Hi Leo!

Why do you use that chunky usb port, and not micro-usb / usb-c ?
 

Offline rx8pilot

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Re: Yet another fast edge pulse generator
« Reply #419 on: October 12, 2018, 08:09:24 pm »
Directional coupler edge over power splitter is its lower insertion loss but the downside is, typically, lower bandwidth.  Or risetime degradation, depending on how you look at it.  Most classic TDR heads I have seen use power splitters. 
Do you want me to look into making one available?

I would be a customer.
Looking into fabricating my own for my 20Ghz sampling scope/TDR. I was thinking of machining the PCB for the 3.5mm connectors and hopefully finding some RF friendly 16.6 Ohm resistors. Then machine an RF sealed enclosure for it.

Then I just need to find someone to help me characterize the result. If they were available for a palatable cost - I would just buy it. >20Ghz is generally rather $$$$
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Offline Leo BodnarTopic starter

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Re: Yet another fast edge pulse generator
« Reply #420 on: October 12, 2018, 08:11:12 pm »
Why do you use that chunky usb port, and not micro-usb / usb-c ?
Have you ever tripped over the cable in the same micro-usb port twice? :)
Leo
 
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Offline simontheu

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Re: Yet another fast edge pulse generator
« Reply #421 on: October 12, 2018, 09:06:37 pm »
Hi Leo!

Why do you use that chunky usb port, and not micro-usb / usb-c ?

Those are blatantly hipster USB connectors!
 

Online Berni

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Re: Yet another fast edge pulse generator
« Reply #422 on: October 12, 2018, 09:15:13 pm »
I like the big chunky USB connectors. These microUSB connectors are crap, they might be rated for more insertion cycles, but they break easier than any other USB connectors and are the most anoying kind of USB connector to plug in with your eyes closed. The previous miniUSB was pretty standard, more robust and easier to plug in while not really being all that much bigger.

I don't have any photos of my DIY power splitter, but what i basically did was solder 3 troughhole SMA connectors together into a star shape with the center pins pointing together. I soldered 0402 size resistors (I think you need 16.7 Ohm each for 50 Ohm at the port) from each SMA together into a common summing point in the middle. The small SMD resistors behave reasonably well a high frequency due to there small parasitics and flat straight construction. To finish it off i wrapped the whole thing in metal tape so that the resistors are completely shielded inside. Soldering those tiny resistors in mid air like that can be a bit annoying but you can throw one of these together in 10 minutes out of parts you likely have laying around.
Here is an example of a similar one that someone else built: http://www.simonsdialogs.com/2014/12/resistive-power-splitter-trying-out-a-low-cost-construction/
It also worked perfectly good to 3 GHz, but again no measurements beyond to see where the limits really are.

Im guessing with careful controlled impedance PCB design and keeping connections short you could build one of these to perform nicely even past 10GHz. Resistors are dirt cheep but the PCB and the connectors could get expensive in a hurry for such high frequencies.
 

Offline rx8pilot

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Re: Yet another fast edge pulse generator
« Reply #423 on: October 12, 2018, 09:21:54 pm »
This resistive splitter is way lower cost than I expected.

https://www.minicircuits.com/WebStore/dashboard.html?model=ZFRSC-183-S%2B
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Offline rx8pilot

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Re: Yet another fast edge pulse generator
« Reply #424 on: October 12, 2018, 09:26:30 pm »
I like the big chunky USB connectors. These microUSB connectors are crap, they might be rated for more insertion cycles, but they break easier than any other USB connectors and are the most anoying kind of USB connector to plug in with your eyes closed. The previous miniUSB was pretty standard, more robust and easier to plug in while not really being all that much bigger.

I don't have any photos of my DIY power splitter, but what i basically did was solder 3 troughhole SMA connectors together into a star shape with the center pins pointing together. I soldered 0402 size resistors (I think you need 16.7 Ohm each for 50 Ohm at the port) from each SMA together into a common summing point in the middle. The small SMD resistors behave reasonably well a high frequency due to there small parasitics and flat straight construction. To finish it off i wrapped the whole thing in metal tape so that the resistors are completely shielded inside. Soldering those tiny resistors in mid air like that can be a bit annoying but you can throw one of these together in 10 minutes out of parts you likely have laying around.
Here is an example of a similar one that someone else built: http://www.simonsdialogs.com/2014/12/resistive-power-splitter-trying-out-a-low-cost-construction/
It also worked perfectly good to 3 GHz, but again no measurements beyond to see where the limits really are.

Im guessing with careful controlled impedance PCB design and keeping connections short you could build one of these to perform nicely even past 10GHz. Resistors are dirt cheep but the PCB and the connectors could get expensive in a hurry for such high frequencies.

I was looking at 3.5mm connectors - which are indeed rather pricey. Vishay (and others) makes specialized RF resistors - but I have not found them in 16.66 Ohm. I thought about using 3x 50Ohm in parallel but that would be a mess to a >10Ghz signal.

The RF resistors are super expensive as well (relative to normal resistors)

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