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| Test Equipment Recommendations for Measuring USB Cable Resistance |
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| reborn1212:
I am looking for tools with somewhat decent accuracy (about 2% in the few dozens to over a hundred milliohms range). After some studying, I listed some choices (in conjunction with USB breakout boards); 1) Micro-Ohmmeter 2) LCR Meter 3) Power Supply and Electronic Load I am a hobbyist and have about a sub-2000 USD budget for this. I am aware of DIY methods to achieve what I want, but I prefer tested products with known specifications across all measured ranges. Also, I am looking to expand my toolset with good value for money items. Recommendations of tools with make / model are highly appreciated. On a side note: Using USB breakout boards inevitably adds significant error when measuring. Any advice on how to mitigate this? |
| srb1954:
--- Quote from: reborn1212 on July 20, 2022, 01:18:14 pm ---I am looking for tools with somewhat decent accuracy (about 2% in the few dozens to over a hundred milliohms range). After some studying, I listed some choices (in conjunction with USB breakout boards); 1) Micro-Ohmmeter 2) LCR Meter 3) Power Supply and Electronic Load I am a hobbyist and have about a sub-2000 USD budget for this. I am aware of DIY methods to achieve what I want, but I prefer tested products with known specifications across all measured ranges. Also, I am looking to expand my toolset with good value for money items. Recommendations of tools with make / model are highly appreciated. On a side note: Using USB breakout boards inevitably adds significant error when measuring. Any advice on how to mitigate this? --- End quote --- A good quality bench multimeter with 4-wire resistance measurement capability would also be suitable and you could easily obtain reading resolutions to 1milli-ohm or lower. The ever popular HP 34401A would be a good choice and is fairly readily available on the second-hand market for reasonable prices. The secret of getting reliable, accurate measurements of low resistances is to use Kelvin probes, which eliminate the errors due to the resistance of your test leads and variations in the connection resistance of your test clips. A good set of Kelvin probes won't be cheap and a name brand might cost almost as much as second-hand multimeter. However, you can buy the special Kelvin clips reasonably cheaply and make up your own probes. If your are testing cables already terminated with connectors you will still have to use a USB socket to connect to but a break-out board shouldn't really be necessary as suitable Kelvin probes should be able to make direct connection to a THT USB connector. I suggest you do some research on 4-wire resistance measurement techniques. The Keithley handbook "Low Level Measurements" is a good starting point for information on this and many other tricky measurement problems. |
| Martin72:
What micro/milli-ohm-meters concerns, I´m happy with my used bought hioki 3450. At work I´ve bought a calibrated one from GwInstek with deliver up to 1A into the testobject. https://www.reichelt.de/de/en/gw-instek-gom-804-dc-milliohm-meter-gom-804-p176003.html?r=1 |
| Tjuurko:
--- Quote ---Using USB breakout boards inevitably adds significant error when measuring. Any advice on how to mitigate this? --- End quote --- Make a homemade ultra-short cable with USB-connectors and use it as a "zero". |
| reborn1212:
--- Quote from: srb1954 on July 20, 2022, 11:29:46 pm ---The secret of getting reliable, accurate measurements of low resistances is to use Kelvin probes, which eliminate the errors due to the resistance of your test leads and variations in the connection resistance of your test clips. --- End quote --- I know about 4-wire measurements with Kelvin probes and the reasoning behind it, just am unsure which benchtop DMMs with this capability and the accuracy I require are within my budget. I'll look up the HP 34401A. --- Quote from: srb1954 on July 20, 2022, 11:29:46 pm ---If your are testing cables already terminated with connectors you will still have to use a USB socket to connect to but a break-out board shouldn't really be necessary as suitable Kelvin probes should be able to make direct connection to a THT USB connector. --- End quote --- I found some THT USB-A connectors, but are THT USB-C connectors commonplace as well? I have several A-C and C-C cables I want to test. Also, do Kelvin probes come in sizes or are one-size-fits-all? |
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