| 摘要 |
PURPOSE:To realize a normal operation of a phase control circuit regardless of a high level of power supply voltage, by adding a diode for suppression of voltage to a switching element for trigger of a thyristor. CONSTITUTION:A resistance R6 and a phototransistor (TR) Q2 are connected between the gate and the anode of a thyristor CR; and diodes D2 and D3 for suppression of voltage are connected between the collector of the TRQ2 and the cathode of the thyristor CR. The TRQ2 does not conduct in case no signal is applied between input terminals 3 and 4, and accordingly, the CR is not turned on. While the TRQ2 conducts when the signal is applied between the terminals 3 and 4, and accordingly, the CR is turned on. Thus a Triac BCR is triggered to supply the electric power to a load 5. |
