| 摘要 |
PURPOSE:To prevent a load from operating by the consumed current of a light emitting diode by connecting the light emitting element of a photocoupler to a load power source through a current limiting resistance. CONSTITUTION:A series circuit consisting of a resistance R3, the light emitting diode of a photocoupler PC2, and a transistor TR2 is connected across a load power source E2. The base current of the TR2 is applied through a voltage dividing circuit consisting of resistances R4 and R5 interposed between one terminal of a load L and the load of the load power source E2. Once the light emitting diode of the photocoupler PC2 turns on, the phototransistor of the photocoupler which is grounded at its emitter and also applied with electric power at its collector through a pull-up resistance R6 turns on. The phototransistor of the photocoupler PC2 sends out a monitor signal to a control circuit C. |
