| 摘要 |
PROBLEM TO BE SOLVED: To provide a DC power supply which can be connected to the AC power supplies in the 100 V region and 200 V region and will not increase heat generated, even if it is connected to the AC power supply in the 200 V region. SOLUTION: The DC power supply comprises a transformer, which is connected to an AC power supply of 50 Hz to 60 Hz, a rectifying circuit which outputs an DC voltage by rectifying an AC voltage, a switching circuit for turning on and off a rectifying diode and a voltage discrimination circuit for discriminating a voltage of the AC power supply. The rectifying circuit includes a smoothing capacitor of 0.33μF to 47μF and the first and second rectifying diodes connected to both ends of a secondary coil, to output a DC voltage by setting an output terminal of the center tap of the secondary coil to 0 V and connect a switch circuit to the second rectifying diode. The voltage- discriminating circuit controls the switch circuit to turn on the second rectifying diode, when it discriminates that a voltage of the AC power supply is the first voltage and turn off, when it determines that a voltage of the AC power supply is the second voltage.
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