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need help in controlling the voltage in a circuit

gurjant.sandhu33

Dec 10, 2013
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Dec 10, 2013
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:greetings every one,
i have made a project on automatically street light controlling by using an ldr. i have used a 6v relay for this. It works fine but when the voltage input to the relay is under 5v it strats to make flickering sound. so, can anyone suggest me a solution to control the current flow to relay upto 6v and after which the current flows normally.
your help will be really appreciated.
thanks.
:)
 

BobK

Jan 5, 2010
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How about using a lower voltage relay.

Bob
 

(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
Moderator
Jan 21, 2010
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Sounds like homework.

Why not Google hysteresis...
 

gurjant.sandhu33

Dec 10, 2013
51
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Dec 10, 2013
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51
thanks for your reply sir,
but my problem is that in my circuit the input to relay varies from 0 v to 6 v and if i will use a lower voltage relay then also at some point this buzzing will occur when the voltage is not sufficient to drive the relay
 

BobK

Jan 5, 2010
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I am going to guess that the problem is that you are simply using a voltage divider with the LDR and a resistor and feeding it to the base of a transistor. If you use a comparator instead, it will work much better, it will snap to the full voltage once the threshold is crossed, and they have built in hysteresis.

Bob
 
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