Mean square voltmeter
S M Bozic · Journal of Scientific Instruments · 1962
A circuit for the measurement of mean square voltages is described in which a temperature limited diode is held at a constant total emission by means of an a.c. servo amplifier using transistors. The response time, determined by the heat inertia of the diode filament and the associated circuitry, is about three seconds, and the stability is good. The scale is linearly proportional to the mean square applied voltage, and the circuit is suited to the measurements of noise voltages in the range 20 c/s-10 Mc/s.