| 摘要 |
PROBLEM TO BE SOLVED: To make an auxiliary power source, which is applied to a base of an emitter/follower circuit using an NPN transistor, obtain a voltage higher than a main power source voltage, with a simple circuit. SOLUTION: An AC power source AC is connected with an input of a bridge rectifier circuit DB. Between the positive and negative terminals of the DB output, a series circuit of an inductor ID1 and a capacitor C1 which constitute a smoothing circuit from the positive terminal side is connected in parallel with a series circuit of a diode D1 and a capacitor C2. A main power source EM outputs a terminal voltage of the capacitor C1 after smoothing. An auxiliary power source EH outputs a terminal voltage of the capacitor C2 which is charged by a peak voltage of a ripple current before smoothing which is charged through the diode D1. These voltages are applied to the base of an NPN transistor operating as an emitter follower. A voltage between the collector and the emitter of the NPN transistor is saturated, so that a small-sized, lightweight emitter/follower circuit of low power loss can be obtained at a low cost. |
