opamp question

Discussion in 'General Electronics Chat' started by nithin ravindran, Jul 2, 2010.

  1. nithin ravindran

    Thread Starter New Member

    Jul 2, 2010
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    Last edited: Jul 2, 2010
  2. hspalm

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    Feb 17, 2010
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    Why is the gain so important when its feature is to rectify?
     
  3. beenthere

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    Apr 20, 2004
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  4. Ron H

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    Apr 14, 2005
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    It works fine. It's not real easy to understand how it works when Vi < 0. See attachment.
     
  5. nithin ravindran

    Thread Starter New Member

    Jul 2, 2010
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    because we need a symmetrical waveform at the output. if the -ve half cycle of the i/p wave is amplified more by the equation 1+(Rf/R1), how can we get a symmetrical waveform? the above situation occurs when -ve half cycle gets inverted by 1st opamp and then passed by lower diode and then amplified by 2nd opamp. my question is what is the eqn for the gain in this 2nd stage? whether it is 1+(Rf/R1)?
     
  6. beenthere

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    Thanks for the explanation.
     
  7. Ron H

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    The gain of the second stage depends on whether the input is positive or negative.
    See the equation and explanation on the schematic I posted.
     
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