One-way silicon controlled voltage regulator circuit diagram

The silicon controlled AC voltage regulator consists of two parts: a controlled rectifier circuit and a trigger circuit. The circuit schematic diagram is shown in the figure below. It can be seen from the figure that the diodes D1-D4 form a bridge rectifier circuit, and the double-base diode T1 forms a relaxation oscillator as a synchronous trigger circuit for the silicon controlled thyristor. When the voltage regulator is connected to the mains, the 220V alternating current is rectified by the diodes D1-D4 through the load resistor RL, forming a pulsating DC voltage at the A and K ends of the thyristor SCR. This voltage is stepped down by the resistor R1 and serves as a trigger circuit. DC power supply. During the positive half cycle of the alternating current, the rectified voltage charges the capacitor C through R4 and W1. When the charging voltage Uc reaches the peak voltage Up of the T1 tube, the T1 tube changes from off to on, so the capacitor C is rapidly discharged through the e and b1 junctions of the T1 tube and R2, resulting in a sharp pulse on R2. This pulse is sent to the control electrode of the thyristor SCR as a control signal to turn on the thyristor. The tube voltage drop after the thyristor is turned on is very low, generally less than 1V, so the relaxation oscillator stops working. When the alternating current passes through the zero point, the thyristor switches off automatically. When the alternating current is in the negative half cycle, the capacitor C is recharged...and so on, the power on the load RL can be adjusted.

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