An application of the diode to the measurement of A.C. voltages
James Taylor · Journal of Scientific Instruments · 1926
The paper contains a description of a method for measuring alternating current voltages by placing a microammeter of the direct current measuring type in series with a diode valve and high resistance. The valve is utilized to provide one-way conduction and the indication of the microammeter is a measure of the average voltage of the alternating supply connected to the apparatus. The apparatus may be calibrated on either A.C. or D.C. There are several advantages in this method of measurement. The microammeter reading is directly proportional to the average voltage of the A.C. supply, consequently the calibration is linear and the voltmeter is equally sensitive over the whole reading range. Further, by increasing the magnitude of the resistance in series with the microammeter, the range of the apparatus may be increased to any extent.