Author Topic: DIY Logic Analyzer Probe and Pods for Siglent (and LeCroy) scopes (Read 54522 times)

mawyatt · « **Reply #25 on:** March 06, 2021, 06:33:55 pm »

Nice video!!

Let us know what you think of the test clips.

Best,

oz2cpu · « **Reply #26 on:** March 06, 2021, 06:44:57 pm »

i got this bunch of hooks for free from a local friend :-)
they are not the ultra tiny tip types
but they do fine for most things specially if there are test points

oz2cpu · « **Reply #27 on:** March 06, 2021, 06:48:05 pm »

I think about adding the one pin female and one wire to each for most flexible solution,
but maybe It is tempting to just add regular IDC type of connector like pictured here,
so if that must be possible, i need to open the sides a bit more, in the 3D pod design !

oz2cpu · « **Reply #28 on:** March 07, 2021, 10:49:40 am »

3D printed parts for the PODS are now done and tested, see here

https://youtu.be/3Ttf7RSYKoU

mawyatt · « **Reply #29 on:** March 07, 2021, 08:28:59 pm »

Made a quick measurement of the scope input at the Digital Connector looking at the waveform attenuation based upon a simple resistive divider (100K with 1M scope probe). This works out to to be ~8.6K looking into the scope digital port line. Using this we made a quick spice model using a 3M 137 ohm twisted pair model, this has a velocity factor of 0.66 and a delay of 2ns (~400mm). As you can see the HP model parameter seem to produce a better overall waveform at the scope, and less perturbation to the input.

Best,

oz2cpu · « **Reply #30 on:** March 07, 2021, 10:15:14 pm »

thanks a bunch, this "reveal" why TK had great luck with the HP system he made :-)
the values simply trimmed it all perfect

oz2cpu · « **Reply #31 on:** March 08, 2021, 10:00:31 pm »

anyone playing with the logic analyzer today ?
I did not :-)
I played with the FFT mode, tested all sorts of frequency ranges,
all the way from 1Hz to 722MHz -5dB point,
I also learned about the full screen options of active features,
so it is very use full just to play a bit too.
amazing dynamic range and visual resolution this type of FFT can do,
see the 1Hz sine wave and its harmonics, now I just need to figure out what I can use this for,

mawyatt · « **Reply #32 on:** March 09, 2021, 12:52:53 am »

Quote from: oz2cpu on March 07, 2021, 10:15:14 pm

thanks a bunch, this "reveal" why TK had great luck with the HP system he made :-)
the values simply trimmed it all perfect

Can you provide a link to this HP System? I've looked without success.

Best,

oz2cpu · « **Reply #33 on:** March 09, 2021, 08:18:41 am »

here you go Mike,
see the bottom of the first post, main thread : Siglent SDS2000X Plus

https://www.eevblog.com/forum/testgear/siglent-sds2000x-plus-coming/

tautech · « **Reply #34 on:** March 09, 2021, 08:36:33 am »

Quote from: oz2cpu on March 09, 2021, 08:18:41 am

here you go Mike,
see the bottom of the first post, main thread : Siglent SDS2000X Plus

https://www.eevblog.com/forum/testgear/siglent-sds2000x-plus-coming/

oz2cpu · « **Reply #35 on:** March 10, 2021, 04:42:33 pm »

the 4 layer scope plug in PCB´s just arrived
now i need to se how easy it is to sand the front connector edge at 20 deg.

oz2cpu · « **Reply #36 on:** March 10, 2021, 08:00:07 pm »

PCB sanding tool, 3D printed and tested

oz2cpu · « **Reply #37 on:** March 11, 2021, 10:53:17 am »

the sanding tool in action, works great, dont even think the screws are needed, the pcb go that tight in, and stay there just fine

mawyatt · « **Reply #38 on:** March 11, 2021, 03:38:57 pm »

Nice

Best,

oz2cpu · « **Reply #39 on:** March 11, 2021, 05:20:28 pm »

a tiny tine adjustment of the 3D printed shell, it turns out the PCB and connector is NOT in centre,
6mm from bottom, 5 mm from top, and the lock grove is 1.4mm wide,
it also works, i see 2nS sample resolution on digital channels

oz2cpu · « **Reply #40 on:** March 11, 2021, 06:37:11 pm »

first 8ch tested :-)

mawyatt · « **Reply #41 on:** March 11, 2021, 07:27:48 pm »

Looks like you may be getting some "ringing" causing multiple edge detection? If so, likely due to the wire/cable/connector terminations.

Best,

DL2XY · « **Reply #42 on:** March 11, 2021, 08:26:39 pm »

This is how it looks on my diy adapter (see https://www.eevblog.com/forum/testgear/siglent-sds2000x-plus-coming/msg3094410/#msg3094410)

DIY Logic Analyzer Probe and Pods for Siglent (and LeCroy) scopes

[ Specified attachment is not available ]
Only the inevitable 500 megasample jitter, even at 10000 sequences.

oz2cpu · « **Reply #43 on:** March 11, 2021, 08:53:32 pm »

look at my timebase, and I used the scopes own probe calibrator as the signal source :-)
it is not that sharp edged,
all i cared about was to verify all channels are right order,
I just put some random resistors in series, and tapped all channels along the way,
to give them all a little bit visual delay to identify them. tomorrow I use a faster, more stable signal source, and see if I can get alot less jitter.

oz2cpu · « **Reply #44 on:** March 13, 2021, 10:35:58 am »

4 digital
1 analog
100ns/div

NO cables, on digital.

oz2cpu · « **Reply #45 on:** March 13, 2021, 10:47:24 am »

here a lot of timebase settings, (this apply to all types of LA hardware, DIY and official hardware, it is a scope thing, confirmed)

the Digital got 2ns resolution (500MSa/s) so of course we expect the level change to be detected in 2ns steps...
however the clock to the digital sampler is NOT in phase or locked to the 2G samples the analog part uses !!!
so the jitter is random, and actually sometimes looking a bit funny depending on your curve frequency. (sample interference)

The same thing apply the other way : if you trigger on digital, they are now steady and locked to each other in fixed 2nS steps.
and now the analog curve gets "wide" from the random jitter. again it is 2nS wide, and it is only visible at speeds under 100nS/div.

the only way to fix this : is to lock the clocks together inside the scope design.

oz2cpu · « **Reply #46 on:** March 13, 2021, 12:04:27 pm »

lets find the perfect resistor values for the trigger levels to work correctly.
sorry still dont have 91k 0603 on stock
so i tried with 100k
and it is a little bit on the low side, see here

circuit:
120R 100k//8p2

https://youtu.be/H0SrdBlnq14

oz2cpu · « **Reply #47 on:** March 13, 2021, 02:22:02 pm »

OK found it..
all the other channels = 120R 100k // 8p2
D3 = 120R 87k // 8p2 now the trigger level is perfect
I used the digital level adjustment, and turned up, until the point where just a tiny pulse is visible, now it is very close to the 4.9V input signal
and it also show a better match in timing to this slow sine

I made 87k with 100k // 680k
this is not the way I like it, E48 series got 86k6 that is perfect

bielec · « **Reply #48 on:** March 13, 2021, 09:31:33 pm »

This has been a wonderful project and the engineering has been very well carried out. I wonder if you would sell one of your pcb's to this man in Scotland?

oz2cpu · « **Reply #49 on:** March 13, 2021, 10:16:55 pm »

sure, the shop is open from next week, when the last pcb, the pod pcb´s arrive,
or you only need the scope pcb ? I got that one all ready.
I can also offer 3D printed parts real cheap, or send your the latest STL files, in case you got a 3D printer ?

you know JLC PCB, they are real cheap, I plan to sell the pcb´s at the double cost i payed, this way I have brake even when halve is sold,
I dont expect to see that many customers.

you got the SMD components ? or can get them easy locally ?

email : my user name, at gmail dot com


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Author Topic: DIY Logic Analyzer Probe and Pods for Siglent (and LeCroy) scopes (Read 54522 times)

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