EEVblog Electronics Community Forum
Products => Test Equipment => Topic started by: t2kv on October 29, 2016, 12:48:48 pm
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Looking to obtain some Kelvin clips, and saw these -- they're four wire Kelvin leads, but built into probes. Does anyone have any experience with them? :-+ ? :-- ?
Are they likely to provide the same accuracy improvement as Kelvin clips over 2 wire measurements?
http://www.pomonaelectronics.com/pdf/d6303_100.pdf (http://www.pomonaelectronics.com/pdf/d6303_100.pdf)
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A slight discrepency between what you're looking for (clips) and what you've linked (probes).
Kelvin clips take the individual signals right to each jaw of each clip, measurement current and voltage sense are completely separated right to the measurement locations. Kelvin probes simply join the signals at the back of the probe tip, this eliminates the effect of lead resistance but do nothing to correct the contact resistance between the probe tips and measurement locations. This may be more convenient in some situations but is nowhere near as accurate for low resistances. It depends how low you want to go.
Edit: If you want decent accuracy in the single or tens of milliohms range, I'd go for clips.
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Thanks, Gyro. Pretty new to this, so appreciate you taking the time to explain the difference and provide advice! :)
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Member iloveelectronics (Franky) does these, have a look at this thread:
https://www.eevblog.com/forum/testgear/franky's-kelvin-clip-kit/ (https://www.eevblog.com/forum/testgear/franky's-kelvin-clip-kit/)
Reply #7 is him and at the foot of his post is his eBay store.
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Pomona quality varies between products. The Pomona Kelvin probes are one of their more junky products.
The soldering inside the probe doesn't withstand use. Dumped mine in the garbage when the sense in the probe failed. It was a few days old. (I had hoped the failure was in the double banana plug, but alas it was in the probe).
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Member iloveelectronics (Franky) does these, have a look at this thread:
https://www.eevblog.com/forum/testgear/franky's-kelvin-clip-kit/ (https://www.eevblog.com/forum/testgear/franky's-kelvin-clip-kit/)
Reply #7 is him and at the foot of his post is his eBay store.
Frank's DIY Kelvin probe kit is awesome quality. Best value on the internet from an awesome seller (ships from HK but arrives in 7-10 days).
EDIT: Just saw that Tautech linked to my review, not Franky's store. Removing the redundant link. I will just mention, Franky doesn't advertise these in his store but message him and he will provide them for you. He has a LOT of stuff that isn't in his eBay store because the eBay store isn't his day job. He just does it because he is a hobbyist like us and has access to a lot of great stuff being basically just across the bay from Shenzen.
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I have the Pomona Kelvin probes, and a set of Kevlin clips as well. The probes are a lot more convenient, I and are far better than standard 2-wire test leads if your meter supports 4-wire ohms.
I would say I have good experience with the Pomona Kelvin probes down to the mid or low tens of milliohms, but if you need milliohm accuracy, you need the clips or 4 wires. Note that if you end up measuring odd-shaped things like PCB traces, you might not be able to position the clips for a measurement.
BTW, had no issues with the Pomona probe quality, but maybe I got a good set. But if they fail, I'll use the leads and make my own tips. The concept is pretty simply.
John