| 摘要 |
PURPOSE:To attain low power consumption by providing a constant voltage element which charges a capacitor with the output voltage and then turns on a switching element and off a switching transistor respectively when the capacitor is charged up to a prescribed level. CONSTITUTION:A commercial power supply AC is connected between terminals T1 and T2 and rectified by a diode D1. This rectified voltage drives switching transistors TRQ1 and Q2, and a capacitor C2 is charged with the outputs of both TRQ1 and Q2. At the same time, the outputs of both transistors are supplied to a constant voltage circuit 1 as the power supply. the constant voltage of the output of the circuit 1 is supplied to a control circuit 2. Here a thyristor SCR is connected to the base of the TRQ1, and the gate of the SCR is connected to a junction between a Zener diode ZD connected to the emitter of the TRQ2 and a capacitor C1. Thus the diode ZD is turned on to charge the capacitor C1 when the capacitor C2 reaches the Zener voltage level. When this charging voltage reaches a prescribed level, the SCR is ignited to turn off the TRQ2. Thus the current is cut to the capacitor C2. |
