Precision Inductance-Capacitance Meter Applying Pulse Width Modulation

Abstract

For accurate measurement of inductance and capacitance, an impedance bridge or a Q-eter has long been used. Each of them, however, is big in size, consumes much power and besides, is a little complicated in use.
The device described in this report is a transistorized precision inductance-apacitance meter which has several characteristics such as low power consumption, long life, easy handling, simple electrical circuit, etc. It consists of a square wave generator, delay circuit, and-gate, amplifier and indicator. Both of the branched square waves are fed to the and-gate, one directly and the other through the delay circuit which delays the time proportional to the value of inductance or capacitance to be measured. Then, pulse width modulated voltage can be obtained as the resultant output of the and-gate. Through such method of measurement, it is easy to keep errors within ±0.5% of the rated value.