| 摘要 |
PROBLEM TO BE SOLVED: To obtain a constant current power supply for use in an electrostatic recorder, e.g. a copy machine or a printer, in which the size of the power supply and the peripherals is prevented from increasing due to large insulation required for high-voltage rise under noload. SOLUTION: The power supply comprises a voltage-doubler-rectifier circuit 5 connected with the secondary winding 1b of a transformer 1, where a diode 13 is connected between a transistor 3 and the primary winding 1a of the transformer 1 and overvoltage protection is effected by detecting the AC voltage at the joint of the primary winding 1a of the transformer 1 and the diode 13. Since the voltage under noload is lowered, by decreasing the difference between the maximum working voltage and the voltage under no-load, size of the power supply and the peripherals is reduced.
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