| 摘要 |
PURPOSE:To reduce the power consumption and realize the miniaturization of an electronic feeding circuit without lowering the performance of the circuit, by connecting a resistance in parallel to the area between the collector and the emitter of the transisitors forming a feedback loop of an electronic feeding circuit of an electronic switchboard. CONSTITUTION:A feedback loop comprising transistors TR1 and TR2, resistances R1 and R2 plus an operational amplifier A is provided to call current supplying circuits BS1 and BS2 that supply the call current to a telephone TEL of an electronic switchboard. A resistance R4 is connected in parallel to the area between the emitter and the collector of the TR1 and TR2 respectively. With this parallel connection of the resistance R4 to the TR1 and TR2, these transistors can operate with a low level of elctric power to realize a reduction of power consumption. At the same time, the circuits BS1 and BS2 can be easily integrated with a miniature structure. |
