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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.
| 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
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 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.
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