12V DC Light Dimmer Circuit Using 555 Timer IC

This is a 12 volt at 2 amp Lamp dimmer that can be used to dim a standard 25 watt bulb by controlling the duty cycle of a astable 555 timer oscillator.





PARTS LIST R1 1KΩ R2 1KΩ R3 100Ω 2W VR1 50KΩ Preset C1 0.1µF (104) C2 470µF 25V D1 1N4001 Q1 BC140 Q2 2N2955 LAMP1 12V Light

When the potentiometer is at the up position, the capacitor will charge quickly through both 1k resistors and the diode, producing a short positive interval and long negative interval which dims the lamp to near darkness.

When the potentiometer is at the lower position, the capacitor will charge through both 1k resistors and the 50k potentiometer and discharge through the lower 1k resistor, producing a long positive interval and short negative interval which brightens the lamp to near full intensity.

The duty cycle of the 200Hz square wave can be varied from approximately 5% to 95%.

You can drive more power light using 2 or more parallel 2n2955 transistors with good heat sink.



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