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need help in controlling the voltage in a circuit

Discussion in 'General Electronics Discussion' started by gurjant.sandhu33, Dec 10, 2013.

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  1. gurjant.sandhu33

    gurjant.sandhu33

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    Dec 10, 2013
    :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.
    :)
     
  2. BobK

    BobK

    7,682
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    Jan 5, 2010
    How about using a lower voltage relay.

    Bob
     
  3. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Jan 21, 2010
    Sounds like homework.

    Why not Google hysteresis...
     
  4. gurjant.sandhu33

    gurjant.sandhu33

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    Dec 10, 2013
    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
     
  5. gurjant.sandhu33

    gurjant.sandhu33

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    0
    Dec 10, 2013
    please
    can you refer me a circuit for hysteresis
     
  6. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Jan 21, 2010
    Sure. Sorry for taking so long.

    LMGTFY
     
  7. gurjant.sandhu33

    gurjant.sandhu33

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    Dec 10, 2013
    thanx...:)
     
  8. BobK

    BobK

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    Jan 5, 2010
    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
     
  9. gurjant.sandhu33

    gurjant.sandhu33

    51
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    Dec 10, 2013
    thanx.....bobk
     
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