Universal polarity test circuit

The invention relates to the field of electrical tests, in particular to a universal polarity test circuit and solves problems of probability of failure in accurate determination, high cost, inconvenience in use and requirement of alternating-current 220V power source support in application of an existing current transformer polarity test method. The universal polarity test circuit comprises a battery, an integrated circuit, four optical couplers, two light emitting tubes, three diodes, eleven resistors, five capacitors, a switch and a terminal block. In testing, input signals are subjected todouble limiting and capacitor filtering through the diodes, polarity judgment is completed by a double-voltage comparator, and self retaining and mutual locking of two polarity indicator light-emitting tubes are realized through the optical couplers. The universal polarity test circuit is simple, clear in principle, easy to operate, reliable in operation, small in size and low in cost; in addition, the circuit is high in