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how to make Automatic light dimmer using LDR? Answered

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I tried to make this light dimmer circuit but it's not worked because of my  LDR exploded 

why is that..  any similar circuit diagram ?

thanks....



This is the circuit i used..

8 Replies

user
Atul009 (author)2014-02-25

there can be 2 possible problems
1)LDR cant work with AC
2)but I think i have seen some LDR work with AC so maybe your R1 is of wrong value tell me what color bands do you see in it
3)power of LDR is very less(the stuff written in watts).

Solutions Try
1)Use a potentiometer in series to your circuit start with highest resistance and decrease it slowly
2)Get a LDR of More power or Watts
3)I think gate of Q1 can be triggered with dc why dont you add a battrie for ldr part.
4)tear the whole circuit apart and try something with DC i.e battries or rectifier. it's better if this is your first experience with LDRs. i can guide personally guide you step by step if this is your first time with LDRs

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user
ishan udyoga (author)Atul0092014-02-25

these color bands have my resisiter-green,yellow,yellow i think it 3.3m..

i think this circuit diagram won't work .

you were right,the broblem is LDR isn't it..

so thanks for the help.. :-)

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user
Atul009 (author)ishan udyoga2014-02-26

green,yellow,yellow color code of 540000 ohms resistor

while you need 3.3M or 3300000 ohms so color code should be Orange,Orange,green

either your shop keeper was a idiot or your multimeter is not working properly and above diagram is also useless what about power of R1.

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user
ishan udyoga (author)Atul0092014-02-26

ooh damn it, yeah it's useless diagram ... thanks.

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user
rickharris (author)2014-02-24

I worry that a) your electronics knowledge seems a bit sketchy and trying to work with mains voltages in such a case is risky to say the least.

b) your not doing simple research like putting automatic light dimmer into google.

https://www.google.co.uk/search?q=automatic+light+...

I can't vouch for any of these circuits but they all look like they stand a better chance than your effort.

PS. Yours will work if you start from a battery supply and a low voltage lamp although your resistor value is perhaps a bit high.

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user
mpilchfamily (author)2014-02-23

Cause your LDR can't handle mains power.

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user

How to fix it pls help...

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