| 摘要 |
PROBLEM TO BE SOLVED: To provide a power supply synchronous pulse signal generating circuit which assures stable operation and provides less deviation at zero-crossing point. SOLUTION: The present invention comprises a rectifier/filter circuit, a photo- diode drive circuit 12 and a detecting circuit 13. The rectifier/filter circuit 11 includes a diode D1, a filter resistor R1 and a filter capacitor C1. The photodiode drive circuit 12 includes a diode D2, a filter resistor R2, a filter capacitor C2, voltage divider resistors R3, R4 connected in parallel to the filter capacitor C2 and a drive transistor Q1 of which base is connected to the connecting point of the voltage divider resistors R3, R4. The detecting circuit 13 includes a detection photocoupler PC1 and an output transistor Q2. The detection photodiode PC1-D is connected between the connecting point of the resistor R1 and the capacitor C1 and the collector of drive transistor Q1. The collector of detection phototransistor PC1-Q is connected to the base of output transistor Q2.
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