Dimming and flashing dual-purpose socket

This dual-purpose socket can be used to dim the light of the lamp plugged into the socket steplessly; it can also make it flash with an adjustable flashing frequency, which can be used to create an indoor atmosphere.

How it works

The circuit is shown in Figure 1. When S is open, the circuit is a dimming socket. The AC voltage is rectified by VD1-VD4 and becomes a DC pulsating voltage, which is added between the anode and cathode of VS. R1, R2, RP and C1 form a RC trigger circuit. When the voltage across C1 rises to a certain value, VS is turned on and the light is lit. When the pulsating voltage applied between the anode and cathode of VS passes through zero, VS is turned off. Adjusting the potentiometer RP can change the charging rate of C1, which changes the conduction angle of VS, so that the voltage across the bulb changes accordingly, achieving the purpose of stepless dimming. The voltage adjustment range across the bulb of this circuit is 150-220V, which meets the dimming requirements of general indoor electric lights. When S is closed, due to the connection of the large capacitor C2, the circuit becomes a flashing circuit. Because C2 has a large capacity and a long charging time, when the voltage across C2 is charged to a certain value, C2 discharges to the VS control electrode through RP and R2, turning VS on and the light is on. When the AC passes through zero, VS is blocked and the light goes out. C2 is recharged, and the cycle repeats to form an ultra-low frequency oscillation, and the light flickers. By adjusting the potentiometer RP, the discharge rate of C2 can be changed, and thus the flickering frequency of the light can be changed.

Component selection and production

The components list is shown in the table below.

It is best to use RP with an insulated swivel to ensure safe use.