A modified Schering bridge for measurement of the dielectric parameters of a material and the capacitance of a capacitive transducer

摘要

Measurement of the dielectric parameters of a material and the change in capacitance of a capacitive transducer by the bridge technique may suffer from errors due to the effect of the stray capacitance between the bridge output lead wires and between the lead wires and the ground. The conventional Wagner-earth technique used to minimise this effect may not be suitable for continuous measurements. In the present paper, a modified operational amplifier-based Schering bridge network is proposed, where the effect of stray capacitance may be assumed to be negligible and continuous measurement is possible. Moreover, the bridge sensitivity may be adjusted by a linear potentiometer. The performance of the bridge network was studied experimentally by assuming a parallel combination of known values of capacitance and resistance instead of an actual dielectric material capacitor or capacitive transducer. The experimental results reported in the present paper reveal the satisfactory performance of the bridge network.