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| Kelvin leads for DMM |
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| Traceless:
Currently I'm looking for a set of kelvin leads to go along with a new DMM. Does anyone have any experience with these? Is there any good reason (other than the extra ground lead) to go with these or these rather than the ebay ones? This seems to be one of the cases where you pay almost 6 times the price just for a brand name, or am I mistaken and there is any real value that justifies that kind of surcharge? |
| TimFox:
I like the idea of shielded wires and a fifth wire for ground, but most modern DMMs seem to lack a "ground" connection on the front panel. When measuring high resistance values with such a DMM, I have a noticeable problem with hand capacitance, even with the metal chassis near the resistor connected to the LO terminal on the ohmmeter (usually two-terminal for high values). |
| mawyatt:
Have a few DIY versions. Left Right is dual with 2 wires & shields, right left is cut off BNC types and replaced with Banana plugs, each wire is shielded, top bottom is small Kelvin clips with unshielded wires and Banana plugs. All seem to work OK for what we need, the best are the individual shielded wire types. Best, Edit: Whoops image came out inside down!! So changed above! |
| Someone:
time to start selling audiophile voltnuttery cryo treated individual triax wired palladium clips with optional antitriboelectric PTFE wire stands? |
| alm:
The clips on the "GW-Instek" leads look quite cheap to me. Also, the way the wire is coiled makes it look quite stiff. The nicer clips, wire and higher-quality gold-plated banana plugs is probably where the extra money goes, beyond brand name and paying for a fairly low-volume item compared to normal DMM probes. Whether this is worth paying 6x as much is of course debatable. You may already know this, but you don't need Kelvin clips to do a four-wire (Kelvin) measurement. It works pretty much as well if you use four separate wires. The only downside is the extra hassle of having to attach four clips, and possibly extra noise pickup unless you twist the wire together (sense with sense, force with force). These kind of Kelvin clips are usually quite large. So they'll fit on unsoldered leaded resistors, but good luck clipping them to a 1/4W resistor that's tightly bent and soldered to a PCB. Never mind any SMD. Four small hook / pincer clips may very well work better for PCB work unless you're measuring a large through-hole current shunt resistor. I only use purpose-built Kelvin clips when measuring loose resistors. For any other four-wire measurement, like in circuit, I'll usually use some other way of attaching the four wires. |
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