| 摘要 |
PROBLEM TO BE SOLVED: To save energy at the time of outputting a constant DC voltage from a switching power supply circuit to be adapted to a television receiver. SOLUTION: When it is required to obtain the DC output voltages E04 to E06 from an AC voltage generated in a secondary coil N5B provided at the secondary of an insulated converter transformer PIT, a control current into the control coils NC2 to NC4 of each universal control transformer PRT-2 to PRT-4 is controlled with control circuits 2 to 4 depending on the level change of the DC output voltages E04 to E06, and the inductance of coils NR2 to NR4 to be controlled is variably controlled. As a result, the DC output voltages E04 to E06 can made constant, and power loss generated by such conversion of the DC output voltages E04 to E06 to the constant voltages can be lowered.
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