PURPOSE: To establish the trigger circuit suitable for the muting control circuit of FM receiver, by stopping the operation of the Schmidt trigger circuit with the control input signal other than the input signal to the circuit.

CONSTITUTION: The base of TR2 constituting the circuit is connected to the first input terminal 1, and the collector is connected to the power supply terminal 4 via the resistor 3 and to the base of TR6 via the coupling circuit 6. Next, the collector of TR6 is connected to the power supply terminal 4 via the resistor 7, and the emmiters of TR2 and 6 are connected to the collector of TR8 after common connection each other. Further, the base of TR6 is connected to the collector of TR9, and the bases of TR8 and 9 are connected to the bias terminal 10 after common connection. The emitters of TR8 and 9 are connected to the ground terminal 13 via resistors 11 and 12, the second input terminal 14 is connected to the base of TR15, and the collector of TR15 is in common with the collector of TR6, and the emitter is connected to the emitter of TR8 via the resistor 16.