The use of capacitance in the measurement of angular and linear displacement

This paper describes the use of capacitor bridges in instrumentation for the measurement of relatively large angular and linear displacements. The particular feature of interest lies in the use of printed circuit board technology which allows repeatability at low cost associated with a rugged overall structure. Two possible electronic configurations are described, one being direct and the other using feedback in which the output depends only on the ratio of the capacitances. Experimental results are given for examples of angular and linear devices. They show that this approach readily yields devices with an accuracy of ±1% and indicates that results considerably better than this are ultimately possible