| 摘要 |
PROBLEM TO BE SOLVED: To provide a power supply, in which the variation in the output voltage level from a plurality of power supply circuits can be suppressed. SOLUTION: Each power supply circuit 1 in the power supply comprises a transformer 3, a switching transistor 4 connected with a primary winding T1 of the transformer 3, a primary control circuit 5 for turning on/off the switching transistor 4, a phototransistor 6a in a photocoupler 6 for switching the operation of the primary control circuit 5, a rectifying circuit 7 connected across a secondary winding T2 of the transformer 3, a light-emitting diode 6b in the photocoupler 6, a resistive element R1, and a diode D1 connected in series between the output terminal of the rectifying circuit 7 and the ground terminal, and a reference voltage source 2. Since the reference voltage source 2 is shared among a plurality of power supply circuits 1, secondary output voltage of each power supply circuit 1 can be controlled accurately.
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