Light dimmer circuit using DIAC and TRIAC

Posted by Srihari Rao On Friday, December 14, 2012 14 comments
Lamp

Light dimmer circuit is using to adjust the illumination of lamp. The below circuit shows the basic TRIAC triggering circuit using DIAC. Here in this circuit the light illumination is controlled using TRIAC and DIAC. 

Working:

The resister and capacitor are connected in series. The capacitor is made to charge through the 500K resistor. When the capacitor starts charging and when it reaches above the breakover voltage of DIAC, it starts conducting. Hence capacitor voltage is applied to TRIAC gate and it turns-on. The charging of the capacitor can be controlled by the variable resistor. Which indirectly controls the firing delay of TRIAC.

Light Dimmer Circuit


You can do this circuit and vary the illumination of the bulb. 

Hope you all like this basic light dimmer circuit. Feel free to comment. 

14 comments:

OHM My said...

Is it ok if i replaced the potentiometer with LDR?

mike said...

what is value of diac and triac

master said...

triac value bt136

ranjitha raveendran said...

what about the maximum load

omkar kamble said...

can I replace 500k resistor with potentiometer

Dan Bc said...

the resistor in there is a variable one.. if it wasnt , this wasnt a dimmer circuit at all

ankit said...

If potentiometer can be replaced by LDR so it can be normal or LDR of higher value to be used?

Vikram Sha said...

Wahat is the maximum load it can handle and can it be used for inductive loads.

chethan nayak said...

Y usually Diac is used for triggering triac....?? can we apply d capacitor voltage directly to d gate f triac..??

Anonymous said...

WELL DONE --U HAVE CLEARED UP THIS DIAC /TRIAC MYSTERY ONCE AND FOR EVER
THANKU SO MUCH --
NOW --WHAT ON EARTH IS A THYRISTOR AND A SCR INRELATION TO DIAC /TRIAC ?

CARL WINTER said...

TAKEN YEARS OF SEARCHING FOR EXPLANATION OF DIAC /TRIAC RELATIONSHIP
& FUNCTION ----SUDDENLY YOUR VERY CLEVER CIRCUIT MADE IT SO CLEAR --
U R A SUPERSTAR -----WELL DONE--

NOW ----WHAT ON EARTH DOES A THYRISTOR DO ? OR SCR DO AS RELATED TO YOUR CIRCUIT -------CANNOT UNDERSTAND WHICH IS WHICH !!

Online Ads said...

Great circuit sir

nathan264 said...

Is this a blog series? If not, it should be. I would love to read the next installment on this subject. koglenlampe.dk

Kiran said...
This comment has been removed by the author.

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