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Sunday, January 12, 2014

12V DC Light Dimmer Circuit Using 555 Timer IC

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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.
12V Lamp Dimmer Circuit Diagram Using 555 Timer IC
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.
555 Timer IC pin configuration NE555 SA SE555 SE555C
555 Timer IC PIN Configuration
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.
BC140 NPN transistor pinout
BC140 PIN Configuration
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.
12V DC Lamp Dimmer Circuit Using 555 Timer IC Light Dimmer Circuit using ne555 2n2955 bc140 12V Lamp Dimmer Circuit Using 555 Timer IC