Ordinary dimming table lamp circuit diagram

The circuit of the dimming table lamp is very simple, just a thyristor voltage regulator circuit. Most of the circuits seen on the market are the circuits shown in the second figure. The working principle is: When the positive half or the second half of the alternating current arrives, the power applied to the thyristor is unidirectional after full bridge rectification. The voltage charges the capacitor through the potentiometer. When the voltage on the capacitor C1 reaches a certain value, the thyristor is turned on. Adjusting the knob of the potentiometer can change the charging time to control the conduction angle of the thyristor. One-way thyristor uses MCR100-6, and diode uses 1N4007. The bulb should be selected from incandescent lamps below 60W.

In the first circuit, the 220V AC power supply directly charges the capacitor C through the bulb and the resistors R1 and R2. When the voltage across the C reaches the conduction voltage of the bidirectional trigger tube (DB-3), the bidirectional trigger tube is turned on, and the bidirectional can be The silicon control VS is also triggered to turn on at the same time, and the bulb is lit. Adjusting R2 can change the charge/discharge time constant of C, thus changing the length of the trigger pulse, changing the conduction angle (conduction degree) of VS, and achieving the purpose of adjusting the brightness of the bulb.