| 摘要 |
PURPOSE:To eliminate a phenomenon of unstable oscillation by giving a part of output current to a switching element control electrode via a resistance and a reverse blocking diode. CONSTITUTION:A self-excited DC-DC converter is composed of a transformer T, a transistor TR1 being a semiconductor switching element and so on and gives a double end voltage Vout of a capacitor C2 as an output to an output terminal 2. Also, this output is connected with an output voltage controlling TR2 base via a zener diode ZD2. In this case, the output terminal 2 is connected with a switching TR1 base through a current limiting resistance R3 and a reversely blocking diode D3. In this manner, when a first action is started, an electric current does not flow through the resistance R3 and the TR2 is also in an OFF-state. Therefore, only an electric current of a starting resistance R1 flows to the TR1 base to start oscillation. If an output voltage Vout rises after start of oscillation, said voltage is added to a TR1 base current to stabilize oscillation.
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