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| Automatic Lamp Dimmer Circuit using Triac |
Lamp dimmers circuit can be found through out the internet since these kind of circuits are have a great significance in real time. Here is a similar circuit which was used to control a AC lamp connected to it based on the light present in the environment. To summarize, this will make the lamp glow brighter in the absence of light and in the presence of light the lamp will glow dim or will be turned off. Lets move into the working of this above lamp dimmer circuit.
WORKING OF AUTOMATIC LAMP DIMMER CIRCUIT:
Triac and LDR holds the significant place in the working of this lamp dimmer. Here LDR (Light Dependent resistor) was used as a light sensor which offers high resistance to the current flow in the absence of light and low resistance when light incident on it. A Triac (Triode for Alternating Current) is a semi conductor device commonly used for switching and power control of AC systems. Triac can be switched On by either negative or positive gate pulse regardless of the polarity of the AC supply input.
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| Triac |
When there is no light in the environment LDR shows high resistance thereby the voltage across the gate terminal of the triac will be high. This makes the Triac to drive the lamp connected to it and the light will glow brighter when there is complete dark. When light intensity was high the LDR shows low resistance therefore the voltage across it will be less or zero. This makes the lamp switch off when the light intensity in the environment was high. The Triac will dim the lamp gradually when there is a increase in light intensity and make the lamp brighter when there is decrease in light intensity.
NOTE:
– AC 220V, 5Watt Incandescent light bulb should be used with this circuit.
– The above circuit can only handle only low loads so never use high loads than the specifications mentioned in the diagram.
– Never touch the circuit or you will be electrocuted.
Hi. How to make a similar circuit for 5v led strip? With a potentiometer to adjust the light?
Thank you in advance.
I don’t need on/off function.
hi i connected as the circuit but the lamp is on in the light in the dark is off
so i need to know how to make it in the dark glow
thanks
Hi Munib,
Not sure why it works in opposite the way it intend to be. Its worth checking your LDR it should exhibit high resistance in dark and low in sunlight
What is the wattage of the 3.3M resistor ?
What about using higher lamp watt value? . and is the ldr can stand this high ac voltage? .
Mohamed,
This circuit is built for 5W lamp. High watt resistor was used along with to prevent LDR from getting damaged.
Hello ,
Ldr’s works this way : in light they gives few resistance and in dark they gives very high resistance.
An Ldr can be used to dim the lights when in light or when in dark or vice versa – it’s a matter to how the Ldr is
connected in the circuit – ok
Sorry for the wrong information and now the article is updated, thanks for pointing out the mistake
Guys i see the LDR found in the market shows high resistance in the absence of light. I believe this circuit need a resistor which should work like a conductor on absence of light. I am not able to find such kind of LDR . Any advice please? –
Guys i see the LDR i found in the market is shows high resistance in the absence of light. I believe this circuit need a resistor which should work like a conductor on absence of light. I am not able to such kind of LDR . Any advice please?
Your point is correct , sorry for the wrong information now the article is updated.