| 摘要 |
PROBLEM TO BE SOLVED: To reduce the price of an element without increasing the voltage of secondary-side output when the voltage of a primary-side DC source is dropped. SOLUTION: In this RCC-system switching supply, the gate of an FET4 is connected to a terminal 31 of an auxiliary coil L3 via a capacitor C1 and at the same time is connected to a zener diode D3 for inhibiting the increase in a gate voltage, the base of a control transistor Q1 is connected to the emitter of a photo resistor Q2, a series circuit 1 consisting of a first resistor R1 and a first diode D1 is connected between the terminal 31 of the auxiliary coil L3 and the collector of the photo transistor Q2, and a second resistor R2 is connected between the gate of the FET4 and the collector of the photo transistor Q2.
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