A PROJECT SEMINAR ON LIGHT DIMMER CIRCUIT USING

TRAIC

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BY

MANISH KUMAYR SHARMA

INTRODUCTION

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This is a standard 220V-240V AC circuit which can be used to adjust the brightness of mains light.It uses a triac,diac,flourescent lamp and generates very little heat .That offer simplicity and high performance .the intensity of the light is determined by the proportion of the sine wave that is applied across the load

CIRCUIT DIAGRAM

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Light dimmer circuit schematic description:This circuit is designed for the 50Hz-60Hz sine wave to accomplish this a bilateral diac is used to control the circuit flow to the traic.Initially the capacitor is discharged and during each half cycle of the input the capacitor is charged to its breakover voltage, when this occurs the diac begins to conduct and discharges the capacitor through the triac gate. it allows the voltage to be applied to the light bulb .

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The intensity of the circuit can be controlled by varying the angle for the circuit .This control by rate at which the capacitor charging. And is determined by this time constant and series potentiometer the RC time constant must be 3-3 Ω and potentiometer lines the 0.1µF capacitance. The smaller the RC time constant ,the quicker the capacitor reaches the breakover voltage and thus the greatest intensity of light can be seen when potentiometer is set to zero, and the greatest portion of sine wave is applied over the bulb

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A simple lamp-dimmer using a triac

Elements Description Quantity Rs

R1 250K 1 2

R2 56K 1 2

R3(Dot) 3.3K 1 1

Diac 2A104J 1 22

Triac BT131,09H 1 25

Capacitor 0.1µF,33T 1 4

Lamp 60W 1 9

Wires - Lump-sump 10

PARTS CIRCUIT ELEMENT

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APPLICATION

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1.The circuit is used for changing the phase angle α= Toff/Tperiod*360

2.By an oscilloscope we measure the amplitude of higher harmonics

3.Speed control by varying the phase angle.

ADVANTAGE AND DISADVANTAGE

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Advantage:1.Simpler and low cost2.Connection by two wires without polarity.3.Absence of a seperate power supply.4.Little power dissipated in resistance and triac.Disadvantage:1.The circuit cannot be used for highly inducting loads.2.Risk of failure over the whole adjusting range.

THANK YOU

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