Simple Multimeter Calibration with a Voltage Reference

Using a voltage reference and a simple technique you can calibrate your multimeters to provide better accuracy. This level of accuracy is far from what a real Calibration Lab would provide, but for some it is enough.
AITRIP Adjustable Voltage Reference
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Voltage Reference Module
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[@mikejones-vd3fg]

Thanks for the tips, i also got a cheap one but i thought it was off reading higher then my others, turns out the others were too low when i checked it against a reference. I used the 3.3v pin on a stm32 microcontoller, maybe not the most accurate but the cheap meter read 3.331 so i figure it was ok, and calibrated the other to 3.3v. It was off by .05v which doesnt sound like much, but even for hobyyists setting proper voltages for batteries, you really dont want to be off by much charging a lithium cell. Good stuff, now i got a another usable multimeter. Even if theyre a little off having them all the same is nice.

[@StuartPatterson]

Thanks! Good idea using a 3.3v pin on the stm32.

[@qno-oj3py]

A bit strange that the pot has this huge range from 4.2 to 5 volts. These 10 turn pots are not known for stability. A bit of vibration could influence the setting. Usually the range is much smaller.
Also check other ranges like resistance and current to verify that the fault was with the pot.

[@StuartPatterson]

Good point. Thanks. Not sure if it is clear in the video but I did not turn that pot much at all. Maybe a quarter turn.

[@ivolol]

Unfortunately DMMs with manual ADC adjustment pots are becoming a thing of the past in modern designs. For instance, UNI-T made an update to this model - UT61E+. It no longer has any pots.

[@StuartPatterson]

Yeah, a few I own don’t have potentiometers either. Nothing is ever easy.

[@mumbaiverve2307]

I have the same DMM. It drifts by about 20mV pretty soon after calibration.

[@StuartPatterson]

Good to know. Thanks.