Photoelectric coupling zero-crossing control socket circuit using TWH9205

As shown in the figure, the circuit includes a zero-crossing drive switch, a photoelectric coupling input circuit, a thyristor control circuit and an audio circuit. The phototransistor switch circuit in the picture is connected to the inverting input terminal (pin 9) of the differential switching amplifier of TWH9205. When the voltage at this terminal is lower than the clamping voltage of the non-inverting input terminal, that is, when the photoelectric transistor 3DU5 is illuminated by light, the TWH9205 The high level is output only when the AC crosses zero, driving the thyristor VS and conducting it, the socket XS is powered, and the electrical equipment connected to XS is put into operation. VS can select a 1-500A bidirectional thyristor according to the power of the electrical load.