Using digital multimeters in place of analog null meters for metrological applications

Historically, analog null meters have been used to determine zero voltage conditions in metrological applications. When digital multimeters (DMMs) became available with resolution comparable to null meters, they were adopted quickly, and analog null meters were set aside. Depending on the circuit and the DMM, significant measurement errors can be introduced. This paper discusses in detail investigations associated with one particular model of precision DMM when used as a null detector and provides measurement configuration details to minimize errors so that the DMM can out-perform analog null meters.