Creating Kelvin Test Leads For Four-Wire Measurments

[VoltLog] has a cheap Hantek LCR meter, but it only has two probes. The best resistance and impedance measurements, though, use four wires to improve accuracy. The first order of business was a custom PCB to fit into the connector of the meter, along with a 3D-printed case.

Using a four-wire scheme requires unusual alligator clips that don’t electrical short the jaws together. The clips were hard to solder and even harder to strain relief. but [VoltLog] seemed to handle it with little problem.

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Circuit VR: Resistance Measurement With Four Wires

If you want to measure resistance and you know Ohm’s law, it seems like you have an easy answer, right? Feed a known current through the thing you want to measure and read the voltage required. A little math, and that’s it. Or is it? If you are measuring reasonably large resistance and you don’t mind small inaccuracies, sure. But for tiny measurements or highly accurate measurements, you’d be better off using the four-wire method. What’s more is, understanding why you want to use the four-wire method is a great example of using an understanding of electronics to find solutions to problems.
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