Being able to verify or calibrate multimeters is something that used to be available only to large labs that could afford to send their equipment off to a metrology lab. But in recent years, amateur voltage standards have become more and more accessible. This small, credit-card-sized voltage standard is good for up to 4.5-digit multimeters.
It’s very portable and can run using battery power. The batteries are charged via USB-C. Four different voltages are selectable: 2.5, 5, 7.5 and 10V. The unit is designed around the venerable Analog Devices AD584, which offers 15ppm temperature stability from 0 to 70C. This design uses the AD584T, which has a base accuracy of +/-15mV in the 2.5V range. Pretty good for testing your average handheld multimeter!
If you’ve wanted to see how accurate your voltage measuring equipment is, this is a great way to do spot checks. If you have a calibrated multimeter that can characterize the reference in this device, you could even use this device to calibrate 4.5-digit multimeters with very high accuracy! The datasheet for the AD584 goes into quite a bit of detail on how the device works and how to get the best performance out of it — definitely worth reading if you pick up one of these!
