voltage comparator

Discussion in 'The Projects Forum' started by tarun.sy, Mar 8, 2011.

  1. tarun.sy

    Thread Starter New Member

    Mar 7, 2011
    1
    0
    Hi

    I am trying to build a voltage comparator which should drive the green led ON only when voltage lies between 12 to 9 v and should drive the red led ON when the voltage falls below 9v.

    For this I tried with LM 393 as well as lm 339 but couldn't get htrough with it.
    My Findings:

    1. With LM 393((pin8)Vcc:5v,(pin4)Vdd:0v,non inverting(pin3),inverting(pin2))

    I have used 2 different presets for the 2 i/p terminals to vary the voltage.

    Whatever be the situation,ie
    a)-i/p>+i/p or
    b)+i/p>-i/p

    o/p always remains high.

    I have tried many other configurations as well.

    Gone through many sites and with different circuits but can not find that small bit where i am going wrong .

    Your support would be highly appreciated .

    Thanks in Advance

    Tarun
     
  2. SgtWookie

    Expert

    Jul 17, 2007
    22,182
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