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LM324 as comparator

Discussion in 'Electronic Projects Design/Ideas/Reviews' started by Bavananth, May 1, 2008.

  1. Bavananth

    Bavananth New Member

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    I have 2 values of dc signals (less than 1.8V and greater than 2.3V ) coming through a line. I wanted to make 5v when I receive "greater than 2.3V" and make 0V when I receive "less than 2.3V". I thought about using an LM324 as a comparator .(The schematic given in the data sheet is attached). But it doesn't work. Could somebody help me please?
     

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  2. ericgibbs

    ericgibbs Well-Known Member Most Helpful Member

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    hi,
    When you say it dosnt work, in what way dosnt it work.?
     
  3. audioguru

    audioguru Well-Known Member Most Helpful Member

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    If the LM324 and the voltage-setting pot have a supply voltage of 6.0V and the output has a load that doesn't draw more than 2mA then the output high voltage is about +4.8V.
     
  4. dave

    Dave New Member

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  5. Bavananth

    Bavananth New Member

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    Thanks It worked. I connected a 3.6Mohm between the earth and the Input(pin 3 and 11). But I don't know the reason.It accidentally worked.(When I connected a voltage meter between the input and earth to check the input voltage it worked as I expected. But when I removed the meter it failed. So I replaced V meter with a high resistance :) ) ??? Just leave this. Thanks again.
     
  6. ericgibbs

    ericgibbs Well-Known Member Most Helpful Member

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    hi,
    Did you try to test it initially without POT2 being connected.?

    If POT2 was in circuit the 3.6M:eek:hm: should not have any effect.?
     
  7. Hero999

    Hero999 Banned

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    Use the LM339 or LM311 as a comparator rather than the LM324 which is a low-power low-speed op-amp not a comparator.
     

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