| 摘要 |
PURPOSE:To avoid spark discharge at switching of a switch by closing the switch so as to make the circuit conductive from the leading point of AC and opening the switch so as to make the cirlcuit nonconductive at the trailing point of an AC current. CONSTITUTION:An AC power supply voltage AC is applied between the base and emitter of a transistor (TR)T through a resistor R3 and a collector current is formed into a rectangular wave of the same frequency as that of the power supply AC. Further, a controlling current is applied from the collector to a gate electrode of a two-way conduction thyristor K by means of a transformer coupling circuit. Further, a collector voltage of the TRT is converted into DC by means of a smoothing circuit consisting of a series circuit comprising a rectifier diode D and a resistor R1 and a parallel circuit comprising a resistor R2 and a capacitor C via a switch S. Thus, the DC voltage is elevated when the switch S is turned on. |
