An automatic inductance test circuit with Go-No-Go type indication

A method is presented to permit the automatic testing of the inductance parameter of magnetic components. The system described provides automatic balancing of the resistive components of the appropriate branches of a Maxwell Bridge. The remainder of the bridge output signal is used to indicate whether the measured inductance is above or below the limit set by the standard arm of the bridge. The balancing is accomplished with a photoresistive feedback element coupling the bridge circuit to a feedback control circuit. This system has resulted in a 6:1 reduction of production line testing time for inductance of some steel core inductors.