Op amp EMF detector

Discussion in 'The Projects Forum' started by kd5vmf, May 8, 2014.

  1. kd5vmf

    Thread Starter New Member

    Apr 25, 2014
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    I need a little help here, I am setting up this circuit for EMF detection and I am not sure if U1 pins 5 & 10 should be ground or +3v (Center voltage). Also if you see anything way wrong that I may have missed.

    Thanks
     
  2. DickCappels

    Moderator

    Aug 21, 2008
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    Connect pin 5 to pin 7 and pin 10 to pin 8 and you should not have any problem with those two amplifiers.
     
  3. kd5vmf

    Thread Starter New Member

    Apr 25, 2014
    6
    0
    DickCappels, May I ask how that would work? I mean how would connecting the pins you recommended cause the amps to function better? It just doesn't sound right, but I am learning all the time. :)
     
  4. DickCappels

    Moderator

    Aug 21, 2008
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    632
    Its very simple: What is usually desired in the case of unused op amps in a multiple op amp package is to keep the unused outputs still so that they cannot interfere with the op amps being used (they are not perfectly isolated from one-another).

    Connecting the non-inverting inputs to their respective outputs results in 100% hysteresis, slamming the outputs against one power supply rail or the other, and we don't really care which rail, as long as it keeps the outputs still.

    Your observation that it doesn't sound right is a good observation; the method is unconventional.
     
    Last edited: May 10, 2014
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