| 摘要 |
PROBLEM TO BE SOLVED: To provide a power-on-demand control circuit of a simple constitution which needs small electric power by placing a control loop consisting of a diode series circuit and bipolar transistor TR between the collector and the base of an output TR. SOLUTION: The emitter of a bipolar TR Q2 whose collector is connected to a power supply potential VCC is connected to the base of an output bipolar TR Q1. A resistance R2 is connected between the base of the TR Q2 and the potential VCC, and the diodes D1 and D2 are connected between the base of the TR Q2 and the collector of the TR Q1. Then the TR Q1 is connected to a power supply potential VEE via a resistance R1. The diodes D1 and D2 generate the voltage drop equivalent to at least the base-emitter voltage Vbe1 and Vbe2 of both TR Q1 and Q2 at the base of the TR Q2. Thus, the base current of the TR Q1 is controlled. |
