| 摘要 |
A power supply circuit securing a stabilized output DC voltage despite increases in the input DC voltage, uses an economical electromagnetic relay, in which a control current Ic' is supplied from a switching amplifier 1 to a control winding Nc' of a saturable ferrite transformer (CDT'). A class A amplifier formed of resistors R1 to R3 and a transistor Q8 of the switching amplifier 1 amplifies a DC input voltage E1 and controls the switching frequency ranging from 100 to 200 KHz according to input DC voltage ranging from 10 to 32V. Resistors R4 and R5 and a transistor Q7 for the switching amplifier 1 form a switching circuit of the control current Ic', while resistors R6 and R7 and a transistor Q8 form a switching circuit for the starting currents of switching transistors Q1 and Q3 of a first and a third half-bridge resonant converter.
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