| 摘要 |
PROBLEM TO BE SOLVED: To reduce loss of a series-regulator type power supply device. SOLUTION: An AC voltage inputted to a power supply device is stepped down by a power supply transformer 3 is rectified, smoothed and outputted as a DC voltage. A switching circuit 10, which opens and closes the connection between an AC power supply 2 and the power supply transformer 3 is connected between the AC power supply 2 and the power supply transformer 3. A control circuit 20 which controls a period while the switching circuit 10 is closed and a detection circuit 40 which detects the value of the output DC voltage are provided. A control circuit 20 controls the closed period of the switching circuit 10, so as to make the output DC voltage value detected by the detection circuit 40 constant, and by having the output DC voltage stabilized, power loss can be reduced.
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