Full Wave Rectifier

Discussion in 'Homework Help' started by ac_dc_1, Jan 30, 2013.

  1. ac_dc_1

    Thread Starter Member

    Jan 27, 2013
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    I am trying to analize this rectifier.I want to determine the expressions of the ouputs and the gain of both Amps and of the montage


    VO1= 0V if Vi>0V

    For the second OpAmp

    Vo2=-R5/R3 Vout 1 - (-R5/R4)Vout for Vin<0 V

    and Vo2=-R5/R4*Vin if Vin>0 V


    Thanks
     
    Last edited: Feb 6, 2013
  2. Audioguru

    New Member

    Dec 20, 2007
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    The circuit works very well when the opamps have a positive and negative power supply.
    The first opamp circuit produces only the negative parts of the input. Its level is doubled by the second opamp and added to the input signal then some of the positive cancels the negative and produces full-wave rectification.
     
  3. ac_dc_1

    Thread Starter Member

    Jan 27, 2013
    74
    0
    So the second opamp has a gain of 2,rigth?
     
  4. Audioguru

    New Member

    Dec 20, 2007
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    The second opamp has a gain of 20k/10k (R5/R3=2) for the half-wave rectified signal from the first opamp and it has a gain of 20k/20k (R5/R4=1) for the input signal.

    Then when the input signal goes negative one amount the output of the second opamp goes positive two amounts which cancels the negative leaving a signal level of positive one.
     
  5. ac_dc_1

    Thread Starter Member

    Jan 27, 2013
    74
    0
    So in conclusion Vo=-vi if Vi<0 and Vo=Vi if Vi>0
     
  6. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
    6,357
    718
    Work out what the voltages would be if the input was +5VDC

    Do the same, but with an input of -5VDC

    From there, you'll have a good understanding of how the circuit works.
     
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