Applications of operational amplifiers in strain gauge circuits

Abstract

Operational amplifiers, originally developed for analogue computation, are now widely used in analogue instrumentation, signal conditioning, servo controls, voltage and current regulators and an extensive range of other functions. In experimental mechanics, operational amplifiers are ideally suited to applications involving strain gauges. Both Wheatstone bridge and ballast (potentiometer) circuits are examined together with the limitations and constraints imposed by amplifier and external circuit considerations. These limitations are important, whether relatively simple operational amplifiers or the more complex instrumentation amplifiers are used. Many manufacturers provide a wide range of ‘off‐the‐shelf’ integrated circuit and discrete amplifiers, together with comprehensive specifications, permitting selection of a suitable device. Before discussing strain gauge applications, the properties of operational amplifiers will be reviewed briefly.