If you like your test equipment and use it often, it’s nice to be able to perform spot checks on the calibration as it slowly drifts over time. For the average hacker, it’s not necessary to send your multimeters and oscilloscopes away to professional calibration services, not only because those services are very expensive, but also because the drift of our devices is small enough that it’s very unlikely to impact our measurements noticeably. However, being able to see if your devices are way out of calibration can be useful, and so this Selectable Precision Resistor Box is a quick way to see how accurate and stable your tools are!
The science of precise measurement is called metrology (not to be confused with meteorology) and it is an absolutely fascinating field. The calibration performed on your test equipment is (usually) traceable back to a national standards laboratory, where extremely precise standards are kept and used to certify the calibration of high-end measurement devices. In this way, a chain of trust can be created so that the calibration performed can be verified against a known and trusted standard.
This Precision Resistor Box comes with four terminals, which allow compensation of the resistance in the probe cables. This method is called a Kelvin four-wire measurement and is the best way to check your device if supported. The precision resistors included are accurate to 0.05% or better; if you get the Pro version, they are all 0.01% accurate with very low temperature coefficients. Additionally, you can use them as current shunts to test both current meters and voltmeters using Ohm’s law — so you can spot-check all your devices. Keep a record of the measurements over time, and you can see if your instruments are going out of spec as they age!
