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what is the value of an LDR for 12V supply?

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arwen

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hye..im creating a light sensor. My question is, what is the value of the LDR that i have to used for a 12v supply and how to know what value that i should use?
 


arwen said:
The problem nw is, when there's no light on the LDR, the LED will turn ON but once i put a light on LDR, the LED is OFF.
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Simply reverse the positions of the LDR and R1. Then the LED will light when there is light and it will turn off when there is no light.
don't let the LDR see the LED.
 

You can learn from this case, that an explaining text must not necessarily be correct, although reverse operation is discussed, too.
The text below the schematic describes the circuit operation correctly.
 

for the relay part, im using a 12VDC PCB Relay for a 12V supply...is it correct?
 

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