| 摘要 |
PURPOSE:To reduce the heat generation of a resistor by so conducting as to produce a partial waveform between a zero potential and a predetermined potential during its period. CONSTITUTION:A load 26 is connected through a triac 27 to both terminals of a commercial power source 1, and controlled to be driven by a photodetector 22 of a photocoupler connected through a rectifier 25. A full-wave rectifier 2 is connected to both the terminals of the power source 1 to full-wave rectify it to supply it to a stepdown circuit 11 of first stage. A sensor block 17 and a light emitting unit 18 and a light emitting diode 20 for forming a photocoupler are energized through a stabilizer 14 from the circuit 11. Thus, in the circuit 11, the output of the rectifier 2 is applied to first, second transistors 5, 6, and when the transistor 5 is conducted, the transistor 6 is interrupted. Accordingly, it is so energized to stabilize the output as to output a partial waveform between a zero potential and a predetermined potential.
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