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One way thyristor dimming light circuit with bidirectional trigger diode

As shown in the figure, it is a unidirectional thyristor dimming lamp circuit suitable for lamp table. 220V AC is converted into 100Hz pulsating DC through vd1-vd4 bridge rectification, and then added to the anode and cathode of the thyristor VT through bulb E. At the same time, in each half cycle of the power supply, the capacitor C is charged through RP and R1. When the charging voltage at both ends of C reaches the conversion voltage (about 26-40v) of the bidirectional trigger diode VDH, the VDH is turned on, and the C discharges to R2. At both ends of R2, a sharp pulse is formed and added to the gate of VT, so that VT is turned on and E is turned on. When VT is turned on, the voltage drop between positive and negative electrodes is about 1V. When the alternating current is over zero, V

As shown in the figure, it is a unidirectional thyristor dimming lamp circuit suitable for lamp table. 220V AC is converted into 100Hz pulsating DC through vd1-vd4 bridge rectification, and then added to the anode and cathode of the thyristor VT through bulb E. At the same time, in each half cycle of the power supply, the capacitor C is charged through RP and R1. When the charging voltage at both ends of C reaches the conversion voltage (about 26-40v) of the bidirectional trigger diode VDH, VDH is turned on, and C discharges to R2. A sharp pulse is formed at both ends of R2 and added to the gate of VT to turn VT on and E is turned on for light-emitting. After VT is opened, the voltage drop between positive and negative electrodes is about 1V. When the alternating current is over zero, VT is turned off. In the next cycle, capacitor C is charged again, and the above process is repeated. Therefore, adjusting the potentiometer RP can change the charging time of capacitor C, so that the average value of voltage on bulb e can be controlled and the brightness can be adjusted.