Adjustable table lamp Working principle is by the resistance R2, potentiometer RP1, capacitance C composed of resistance phase shift circuit, adjust the RP1, you can change the bidirectional thyristor V's Guide angle, thus changing the brightness of the light bulb EL. Resistance R1 limit flow resistance. The charging speed of C is also related to the parallel circuit. In the case of R1 and RP2 fixed, the size of the shunt is determined by the resistance value of Photoresistor RL. When the voltage of the power grid rises, the brightness of the light increases, the RL resistance becomes smaller, the shunt increases, the voltage of the capacitance C at both ends slows down, the V-guide angle of the thyristor decreases, the output voltage decreases, and the brightness of the light decreases, and conversely, when the voltage of the power grid drops, the RL resistance is increased The brightness of the light is automatically stabilized at the set value.