| 摘要 |
PURPOSE:To prevent a current from flowing round by connecting a diode in series to a resistor connected to the base of a transistor of a main circuit. CONSTITUTION:There is provided a diode 26 having an anode connected to a resistor 22 which is connected to an emitter of a driving transistor 18 and a cathode connected to negative side of the second DC power unit 14A. According to this constitution, an emitter terminal voltage of a transistor 12 of a main circuit (5) becomes almost equal to a positive side terminal voltage of a DC power unit 10, when the transistor 12 of the main circuit (5) is kept on, and the transistor 12 of the main circuit (5) can thus be prevented from being on, thereby keeping a short-circuit mode from arising to the DC power unit 10. |
