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

[Wahyueko]

The pcb arrived, it's not compatible with MSO5000 Tektronix, hehe.
now I'm trying to measure the dimensions of the pcb and the plate in it. all have 40 pins. after I measured it looked like there was indeed a 16-pin signal. 17pin Ground, 1pin NC, 2 pins I measured to gnd the resistance read 110Ohm BDV 0.1V, and 4 pins resistance to ground 10k Ohm BDV 0.58V. and I try to make it again. I don't know what the 2 pins and 4 pins are for and 1 NC pin.

[Uppic]

Hi, I have recently retired and taken up my hobby. They gave me a PM3885 that was cornered in a storage room, but without cables. The question is, could this pod probe serve me for the Philips PM3585. thank you very much to all.

[oz2cpu]

>could this pod probe serve me for the Philips PM3585.

NO

[julian1]

This question is not specifically about the DIY version (have one ordered), but this thread has the most SPL2016 info/knowledgable.

If one wanted a dedicated 2x8 or 1x10 IDC pcb connector, to plug the SPL2016 LA cable directly,

What termination/passives are needed to match the pod/flying lead assembly - if anything?

I measure 91R series resistance, for the pod/flying leads. 

Note, Siglent support this configuration when direct connecting their LA test generator board (see Defpom http://youtu.be/X_cVpH7GLtI?t=88 ).

[julian1]

I found a close-up pic of the Siglent pattern generator that supports a directly connecting to a pcb idc header. There don't appear to be any passives used near the connector.

[teddychn]

Rob,

Thanks for the data, here's what we came up with as a quick estimate model of the LA. The Digital Input pulse was manipulated to try and create what we think the actual pulse to the LA looks like, and show the offset as shown on your DSO measured trace above.

The Digital Probe wire self inductance is based upon 200 & 150mm of #26 AWG wire, the 1100mm coaxial cable (shown as twisted pair in schematic) is modeled as having a Zo of 45 ohms and delay of 6.1ns based upon a velocity factor of 60%. Later we'll need to see how the twisted pair cable (and ribbon) rather than the coaxial cable effects these simulations.

Hi Mike,

This thread is informative. I'm trying to adapt my existing 54622D logic probe to SDS2104X HD and conduct some simulations concurrently. However, I'm not sure what R1 and C2 in your simulation represent. Have you already known the impedance model of the SDS2000X Plus/HD logic port?

Thanks,
Ted

[mawyatt]

Rob,

Thanks for the data, here's what we came up with as a quick estimate model of the LA. The Digital Input pulse was manipulated to try and create what we think the actual pulse to the LA looks like, and show the offset as shown on your DSO measured trace above.

The Digital Probe wire self inductance is based upon 200 & 150mm of #26 AWG wire, the 1100mm coaxial cable (shown as twisted pair in schematic) is modeled as having a Zo of 45 ohms and delay of 6.1ns based upon a velocity factor of 60%. Later we'll need to see how the twisted pair cable (and ribbon) rather than the coaxial cable effects these simulations.

Hi Mike,

This thread is informative. I'm trying to adapt my existing 54622D logic probe to SDS2104X HD and conduct some simulations concurrently. However, I'm not sure what R1 and C2 in your simulation represent. Have you already known the impedance model of the SDS2000X Plus/HD logic port?

Thanks,
Ted

Hi Ted,

These (R1 and C1) were used to attempt to mimic the Siglent response tautech had shown earlier, check the thread prior to the one this schematic originated from. You can see the simulated response and compare to the one tautech posted.

We used twisted pair for the signal lines and later just ribbon cable, recall both worked well for our needs, memory's not that good tho 

Anyway, at one time we were going to "tweak" the component values for optimum response but never needed to do such, as it worked well enough for our needs right from the start as shown, so we've never revisited this since.

Best,

[teddychn]

Thanks Mike,

After some trials, I found that the cable length has a significant impact because the transmission line impedance doesn't perfectly match the LA's input impedance. I'm starting by inserting a 75-ohm resistor at the front end of the microstrip line of the adapter. I feel the front end resistor of the LA adapter in your picture seems to be ferrite beads, am I right?

[mawyatt]

No ferrite beads were used, just R and Cs I recall.

Best,

[KungFuJosh]

I bought one of the DIY type LA probes on eBay for $40 shipped. It worked great in the Batronix MSO board tests. I assume the seller is a member of this site.

[mawyatt]

Likely copies of Thomas (oz2cpu) original work, not sure if authorized or not. As clock speeds increase the details of the probe begin to show, this includes the type and nature of the cables utilized. These are improper terminated cables on both ends, either coaxial, twisted pair, or ribbon type with SGSG configuration.

Tautech kindly provided what the OEM Siglent Probes waveforms looked like, so we attempted to duplicate that performance blindly, meaning not knowing about the details inside the DSO case, and created a model for what we "thought" might be a good representative, proof being did the simulation waveform resemble the tautech provided actual waveform.

So we created our version based upon this and planned to "tweak" the component values and such to optimize the performance. We never got around to this optimization tho, as the 1st cut performed well enough for our needs at the time, and we haven't had a need to revisit this for improved behavior.......yet 

Best,

[KungFuJosh]

So we created our version

Gonna share? 😉

[mawyatt]

So we created our version

Gonna share? 😉

All listed within this thread

Best,

[KungFuJosh]

Likely copies of Thomas (oz2cpu) original work, not sure if authorized or not.

Well, now that I've read the thread, I know who the seller was. It did work well on the MSO demo board. 🤷

[tautech]

These (R1 and C1) were used to attempt to mimic the Siglent response tautech had shown earlier, check the thread prior to the one this schematic originated from. You can see the simulated response and compare to the one tautech posted.

We used twisted pair for the signal lines and later just ribbon cable, recall both worked well for our needs, memory's not that good tho 

Anyway, at one time we were going to "tweak" the component values for optimum response but never needed to do such, as it worked well enough for our needs right from the start as shown, so we've never revisited this since.

Best,

Now I have new and better SMD tweezers (ST42) I can do these measurements again if required including mainboard input measurements on a warranty replacement board.
Maybe these is a termination network there too that could help with a better match.

Tell me what you need. 

[teddychn]

Maybe these is a termination network there too that could help with a better match.

You're very possibly right. Here's the information in the 54622D manual:

[KungFuJosh]

I want to build oz2cpu's version intended version of this. Is there a limitation to the length of the wires used? And what's the best wire for use with this?

Thanks,
Josh

[tautech]

I want to build oz2cpu's version intended version of this. Is there a limitation to the length of the wires used? And what's the best wire for use with this?

OEM are 1M long 8ch pairs of micro-coaxial ribbon cable.

Find one from another brand and modify it as Defpom did here:
https://www.eevblog.com/forum/testgear/diy-logic-analyzer-probe-and-pods-for-siglent-scopes/msg3691729/#msg3691729

[KungFuJosh]

Has anybody tried shielded ethernet cable? It's 4 sets of twisted pairs (2 per pod). Cat6A is rated up to 500MHz. Regular Cat6 is rated 250MHz, and Cat7 and Cat6E are rated for 600MHz. Cat8 is rated for 2GHz. Aren't all of those beyond the capability of the DIY adapter?

[Martin72]

Hi,
I´ve bought the original SPL2016 and post it in the Siglent HD thread, with pics.
https://www.eevblog.com/forum/testgear/siglent-sds2000x-hd-12bit-(published-for-chinese-domestic-market-only)/msg4997911/#msg4997911

Now you must do a battle with the clone version.

Clone version...I don´t know a clone version(where to buy), but If I can help finding things out I´ll do (except opening something).
Got the STB-3 demoboard and the batronix demoboard here, if I should measure something with them, let me know.

[KungFuJosh]

Clone version...I don´t know a clone version(where to buy), but If I can help finding things out I´ll do (except opening something).

The files (gerbers and 3D print) are available in the first post of this thread. Another project for you to build. 😉

[kripton2035]

I bought my clone on ebay : https://www.ebay.com/itm/225024212937
arrived in france in a few weeks.
at that kind of price I did not bother to build my own.


oh and there was some delay in the shipping, the item seemed to be stuck somewhere
the seller was very kind and responsive.


the hooks are some kind of first price one, but they work. you can buy better one eventually.

[KungFuJosh]

I received the PCBs, but I'm having issues with the 3D parts.

JLC is giving an under 1mm thickness warning for the parts. Did anybody else have that issue? Is that correct, or is there something wrong with their system or the 3D models?

Thanks,
Josh

[Martin72]

Got the same message from the 3D parts of the voltage reference (not the heater case).

[KungFuJosh]

Got the same message from the 3D parts of the voltage reference (not the heater case).

Me too, that's partly why I'm concerned. I hope it's not a design file compatibility issue with JLC.

Did you get the parts in yet?