Recommendations for long (5-15 meter) test leads for DMM and/or Oscilloscope? - Page 1
Forum section: electronics / testgear

author: victorhooi
author_rank: Regular Contributor
timestamp: September 23, 2024, 01:57:51 am
content: Hi,I need to diagnose some potential issues in the field with very long digital addressable LED strips (~ 20m long strips). The strips are glued inside an aluminum profile, which is then glued to the ceiling quite high up (there is a lift platform available). I suspect I'm going to need two people, one for each of the two probes, to push it down to the contact pads on the strips:Thanks to @artag for some super helpfuladvice here.However, even with a DMM and oscilloscope (will need to figure out a way to make my Analog Discovery ADP2230 portable, haha), I still need to find a long enough lead to reach test points along the LED strip.My standard DMM leads are only around 36" (91cm) - and my oscilloscope leads I believe are similar.I looked at Probemaster (where I got my leads originally), and the longest lead them have is 120" (~3m).https://probemaster.com/9151-probe-lead/I did find these leads online (LANG1130) - they're 30" (10m) - but they seem to have alligator clips on the end, not banana plugs - so assuming they can't be used here?https://www.henchman.com.au/LANG1130/Test-Lead-retractable-30ft/pd.php?srsltid=AfmBOoqSVS7LykHK8ArNgl--hzX3YoB9cfHBGro9QLMYuu1hkjsv3P3kOr there's this version - which has 3 leads - but is only 10" (3m) - and once again only has alligator clips, not banana plugs:https://sydneytools.com.au/product/te-tools-3346-10ft-3050mm-3-colour-retractable-test-leadsElement14 also has their in-house Multicomp Pro brand ones - 5m (green), 10m (yellow), 20m (red) - however one end seems to be a fixed alligator clip as well:https://au.element14.com/multicomp-pro/mp770519/test-lead-set-plug-alligator-clip/dp/349049202(datasheet)I did find RS Components does have aTest Lead Extension Reels category. In there, they have one of their in-house brand black leads, 12m long - with banana plugs on both ends:https://au.rs-online.com/web/p/test-lead-extension-reels/6120829(datasheet)Mueller Electric is a US company that specializes in cables - they have these two test lead reels that are 40' (12.19m) - seem like good quality options:https://www.muellerelectric.com/products/ai-5920t1202https://www.muellerelectric.com/products/ai-5920t11-0Digikey has this Pomona set - 144" (~ 3.5m):https://www.digikey.com.au/en/products/detail/pomona-electronics/EM5908A-144/6125877Anyway - it seems so far that the Mueller Electric set is the best option - 12m long, seem like a reputable company.If I want 3m long ones - I guess maybe Probemaster or Pomona are the best options?For the oscilloscope - from what I've read, I can't simply extend the existing oscilloscope probes with a BNC extension cable, right? I don't need a massive amount of bandwidth, I just want to make sure that the digital signaling for the strips is getting through (artag suggested even 10Mhz would be fine).RS Components also has this 7.6m BNC cable:https://au.rs-online.com/web/p/test-leads/1799397Or what else would people suggest to extend the oscilloscope probes?Thanks,Victor

author: KungFuJosh
author_rank: Super Contributor
timestamp: September 23, 2024, 02:10:24 am
content: Have you considered getting a portable scope like a Micsig?

author: victorhooi
author_rank: Regular Contributor
timestamp: September 23, 2024, 02:32:59 am
content: Quote from: KungFuJosh on September 23, 2024, 02:10:24 amAha - I actually have an older Micsig =) - but the battery had issues, and I found the OS a bit dinky. If you have one - how are the newer models?However, I've just checked - the ADP2230 can apparently be powered by just USB 3.0 power alone. So if I just have my laptop, and connect that to the ADP2230, it should be portable (just not all integrated like say a Micsig, which is basically an Android tablet). From the ADP2230 spec sheet, it seems like there's some restrictions on using the ADP as power-supply when using it with just USB power - but I just need it as an oscilloscope here.https://digilent.com/reference/test-and-measurement/analog-discovery-pro-2230/specificationsHowever, that still doesn't sort out the issue with the length of the DMM leads, or the oscilloscope leads - as in, if I need to read two different points that are far apart along the 20 meter LED strip.

author: KungFuJosh
author_rank: Super Contributor
timestamp: September 23, 2024, 03:10:45 am
content: I don't have a Micsig, but I know a lit of people like them for this sort of thing. My only portable scope is a toy not worthy of discussion. 😉I guess I don't understand how you're probing. I assumed you would be going with a ground connection and probe tip to what you're testing. Ground is common throughout that strip, so I assumed you wouldn't need the leads to be long if the scope could get close.

author: victorhooi
author_rank: Regular Contributor
timestamp: September 23, 2024, 01:30:55 pm
content: Yes, you're right =) if I'm only measuring the data signal at one point, then I can just use a probe with a short lead, and also tap into the ground right next to it.However, the ADP2230 I have does have two channels - so if I wanted to compare the LED data signal at the start of the strip, versus the signal later down the strip, or even towards the end - then that's where I'd need at least one of the leads to be slightly longer.For the DMM on the other hand - I think I will probably need longer leads from the start - as I need to measure resistance between various points along the 20 metre LED strip, to see if there's any breaks in continuity (although I'm open to ideas here).

author: coromonadalix
author_rank: Super Contributor
timestamp: September 23, 2024, 01:49:36 pm
content: yes get a protable scope ...long wires will complicate things, antenna effects, capacitances , impedances, parasistic problems ... and finally safety issues

author: KungFuJosh
author_rank: Super Contributor
timestamp: September 23, 2024, 05:02:04 pm
content: Quote from: coromonadalix on September 23, 2024, 01:49:36 pmExactly this.You can use 1 channel at a time on a portable scope, save screenshots with measurement data, and compare after. Live comparisons aren't necessary, and will complicate things logistically.

author: victorhooi
author_rank: Regular Contributor
timestamp: September 24, 2024, 12:35:23 pm
content: Hi,Got it - yeah, I can just use a single channel on the scope, and move along the strip, bit by bit.For the DMM - if I need to check continuity, or try to see if there are shorts between adjacent pins (e.g. data to ground).Should I just get the 12 meter banana extensions?https://www.muellerelectric.com/products/ai-5920t1202Or if there another way you achieve this?Thanks,Victor