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  • PWM Lamp Dimmer

  • Created: Sep 25, 2014

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This circuit is a simple yet efficient lamp dimmer. It uses pulse width modulation to dim the intensity of the lamp. The main component of the circuit is an NE555 timer where the duty cycle varies. When duty cycle varies, it will generate a pulse with different widths causing the lamp's brightness to either increase or decrease. The PWM based dimmer that has a maximum efficiency of 90 percent is more efficient than using a linear regulator which has a maximum efficiency of 50 percent. Thus, this PWM lamp dimmer delivers high efficiency that is excellent for changing the ambience while saving energy consumption.

NE555 timer IC is a precision timing circuit capable of producing accurate time delays or oscillation. In the astable mode of operation, the frequency and duty cycle can be controlled independently with two external resistors and single external capacitor.The circuit is wired as an astable multivibrator operating at 2.8KHz which is the brain of this circuit. Resistors R1,R2, POT R3 and capacitor C1 are the timing components. Duty cycle of the IC's output can be adjusted using the POT R3. The higher the duty cycle means the higher the lamp brightness and the lower the duty cycle means the lower the lamp brightness. Diode D1 by-passes the lower half of the POT R3 during the charging cycle of the astable multivibrator. This is done in order to keep the output frequency constant irrespective of the duty cycle. Transistors Q1 and Q2 form a darlington driver stage for the 12V lamp and resistor R4 limits the base current of transistor Q1.

PWM Lamp Dimmer can be used to any electric lights or light emitting devices such as table lamps, fluorescent, or LEDs that are convenient to the user. This can alter the ambience of a certain environment by adjusting the light's brightness while conserving energy by allowing the lamps to last longer by at least 25 % of its life span. Furthermore, this is essential to users that demands to save energy while leaving their houses secured by keeping the lights on during night time.



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