Automatic Check and Calibration of Digital Voltmeters

Reliable measurement values require constant attention to the performance of the instruments. Great benefits would be achieved if the instruments had built-in fail-safe automatic check procedures. A new principle has been developed for automatic checking and calibration of a digital voltmeter. The entire instrument from the input terminals to the display is included in the check. To check the reference voltage two references are used, and they are automatically compared to each other. For each measurement value the instrument simultaneously checks itself. A simple single ramp voltmeter has been equipped with this self-checking device, and very promising results have been achieved.