Light Dimmer Circuit Using TRAIC

A PROJECT SEMINAR ON LIGHT DIMMER CIRCUIT USING TRAIC

BY MANISH KUMAYR SHARMA

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

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CIRCUIT DIAGRAM Light dimmer circuit schematic description: This circuit is designed for the 50Hz-60Hz sine wave wav e to accomplish this a bilateral diac is used to control the circuit circuit flow to to the traic.Initially 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 voltag voltage e to be applied to the light bulb . 3

The intensity of the circuit can be controlled by varying the angle for the circuit .This control by rate ra te at which the capacitor charging. And is determined by this time constant and series potentiometer potentiomet er the RC time constant constant must be 33  and potent potentiom iomet eter er lines lines the 0.1µF capacitance. capacita nce. The smaller the RC time const constant ant ,the quicker the capacitor reaches the breakover voltage voltag e and thus the greatest intensity intensity of light can be seen when potentiometer is set to zer zero, o, and the great greatest est portion of sine wa wave ve is applied over the bulb 4

A simple lamp-dimmer using a triac

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PARTS CIRCUIT ELEMENT 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 6

APPLICATION 1.The circuit is used for changing the phase angle = Toff/Tperiod*360 2.By an oscilloscope we measure the amplitude of higher harmonics 3.Speed control by varying the phase angle.

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ADVANTAGE AND DISADVANTAGE Advantage: 1. Sim Simple plerr and low low cost cost polarity. 2. Connection by two wires without polarity. 3. Absence of a sepera seperate te power power supply. supply. dissipated in resistance resistance and and triac. 4. Little power dissipated

Disadvantage: 1. The circuit circuit cannot cannot be used for for highly inducting inducting loads. failure over the whole adjusting range. 2. Risk of failure

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THANK YOU

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