Fast-reading DVM with real-time autocalibration

The voltmeter described gives high accuracy and stability at reduced cost and with simplified calibration. It measures direct and alternating voltages and resistance. Under programmed control, it can make 25 direct-voltage readings per second with 5½ digit resolution. Alternating-voltage readings are made at a rate of 13 per second, also under programmed control. The true-RMS converter has a frequency range of 0–8 MHz, a crest factor of 10: 1, and AC and DC capability. The voltmeter calibrates itself by accounting automatically for gain and offset errors.