| 摘要 |
A solid state relay includes a light emitting diode receiving an input signal for emitting light, a photodiode array located to receive the emitted light for generating a photo voltage, a MOSFET having its gate connected to an anode of the photodiode array so as to receive the photo voltage. A source and a drain of the MOSFET are connected to a pair of output terminals, respectively, and an anode and a cathode of a thyristor are connected to the anode and a cathode of the photodiode array, respectively. A phototransistor is located to receive the emitted light. A collector and an emitter of the first phototransistor are connected to the cathode of the photodiode array and a positive gate of the thyristor, respectively. When the light emitting element is energized to emit the light, the phototransistor is turned on so as to turn off the thyristor. When the light emitting element is deenergized to emit no light, the phototransistor is turned off so as to turn on the thyristor.
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