Wheatstone bridge amplifier circuit

Discussion in 'Homework Help' started by jstrike21, Feb 25, 2010.

  1. jstrike21

    Thread Starter Member

    Sep 24, 2009
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    [​IMG]
    I found Vout of just the wheatstone bridge part is:
    Vin((10.01/20.01)-(10/20))
    Using 5 as Vin i got Vout=0.00025V

    Does the 0.00025 Volts go to the + terminal of both of the op amps?
    I'm not sure how to solve from here.

    I know the transfer function of the amplifier circuit:
    [​IMG]
    is
    [​IMG]
    would I use the 0.00025 as Vin2 and 0 as Vin1?
     
  2. jlcstrat

    Active Member

    Jun 19, 2009
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    I would think that sounds right. I have been wrong quite often though
     
  3. jstrike21

    Thread Starter Member

    Sep 24, 2009
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    thanks, can anyone verify this?
     
  4. jstrike21

    Thread Starter Member

    Sep 24, 2009
    104
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    forgot to multiply by 5, Vout for the wheatstone bridge is .00125V
     
  5. jlcstrat

    Active Member

    Jun 19, 2009
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    The more I look at this, the more I think V2 should be 2.5, and V1 2.5012.
     
  6. jstrike21

    Thread Starter Member

    Sep 24, 2009
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    ya but still when you out those into the final equation you will subtract them and end up multiplying by .00125
     
  7. t_n_k

    AAC Fanatic!

    Mar 6, 2009
    5,448
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    I would imagine in a real circuit implementation there would be a power supply common reference at some point - say at the lower point of the bridge. Otherwise one might have issues with lack of conducting paths for input bias currents - should they be non-zero.
     
  8. t06afre

    AAC Fanatic!

    May 11, 2009
    5,939
    1,222
    Google -> instrumentation amplifier This will give you some tips. A instrumentation amplifier will amplify the difference between the two inputs.
     
  9. jlcstrat

    Active Member

    Jun 19, 2009
    58
    3
    It's going to amplify the difference, but as far as the formula goes wouldn't you use 2.5 and 2.5012 for the V in 1 and 2? I thought that was the original question.
     
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