What is the flaw in this op-amp circuit?

Discussion in 'General Electronics Chat' started by rkbshiva, Aug 19, 2015.

  1. rkbshiva

    Thread Starter New Member

    Aug 1, 2015
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  2. pwdixon

    Member

    Oct 11, 2012
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    The thermocouple produces a voltage not a current for the circuit to work, as it does in fact point out, the thermocouple would need to source current into both inputs ie. it would be a current generator.
     
  3. rkbshiva

    Thread Starter New Member

    Aug 1, 2015
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    Sorry!Can you please elaborate your answer.I can't get you
     
  4. kubeek

    AAC Fanatic!

    Sep 20, 2005
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    Both inputs act like a current source with the same polarity, so if you just connect them together you will get bogus results. You need to provide a way to close the loop for those currents.
     
  5. crutschow

    Expert

    Mar 14, 2008
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    Also, there needs to be a path for the op amp input bias currents to ground.
    Op amps cannot operate with the inputs floating.
     
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