Working principle of adjustable desk lamp is made of resistor R2, potentiometer RP1, c composition RC phase-shift
Circuit, RP1, can be changed bi-directional thyristor breakover angle of v, thus changing the bulb brightness of EL. Resistor R1 resistor within the limit. C charge rate associated with the parallel loop. In the case of R1, RP2, fixed, split size decided by photoresistors resistance RL. When the voltage rises, lights brighter, RL value gets smaller, shunting increases capacitance c voltage rise slowed, v of thyristor conduction angle decreases, the output voltage decreases, luminance decline and vice versa when the voltage drops, RL value increases, shunt decreases thyristor conduction angle increases, the output voltage increases, light levels increase. In this way, light is automatically stabilized at a set value.