Another full wave rectifier

Discussion in 'General Electronics Chat' started by nad, Feb 12, 2009.

  1. nad

    Thread Starter New Member

    Feb 9, 2005
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    Thanks for your reply Mic3. I apologise for my ignorance; though I believed my subject to be related to this thread.
    i have attached a file with my design for a full-wave rectifier with smoothed out DC output and integrated Common Mode Rejection. I hope this circuit will be of use to the members. The circuit has good linearity from 10 mV up to 2.5 Volts with frequency ranging from 50 Hz up to 100 kHz. I have found the accuracy to be less than 5 mV. The circuit works well in simulation, and as constructed hardware . I would apprecaite any comment and suggestions.

    regards
    Nader
     
  2. mik3

    Senior Member

    Feb 4, 2008
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  3. nad

    Thread Starter New Member

    Feb 9, 2005
    6
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    Mic3

    you are quite right. That will work; though, it will only give smoothed half-wave rctified. Furthermore, I found that this method is very limited in its range, and Opamp saturates at higher voltages above 500mV. My circuit needs to measure the voltdrop across a shunt with input currents varying from 10 mA to 10 Amps. Sorry for discussing this issue in this thread. Should I start a new one? I am only trying to share my experiences and ideas with others and be of help if I can; bearing in mind that I am new to Opamp design.

    Many thanks for your replies and suggestions.
    Nader
     
  4. mik3

    Senior Member

    Feb 4, 2008
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    If you design it properly then it won't saturate at 500mV.

    What is the power supply for the op amp?

    Will you sense an AC current?
     
  5. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
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    Welcome to AAC, nad. We discourage thread hijacking, as it leads to consufion. Always start a new topic in its own thread.

    This is the thread that got hijacked - http://forum.allaboutcircuits.com/showthread.php?t=9821&page=2.

    A note - your circuit is overly elaborate. The "original" out of the National Semiconductor op amp circuits collection followed by an inverting stage with a 1 - 10 uF cap across the feedback resistor gives excellent results. Your 2200 uF cap is going to seriously strain the poor op amp trying to push current onto and off of that monster.
     
    Last edited: Feb 12, 2009
  6. Audioguru

    New Member

    Dec 20, 2007
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    The simple circuit does not need "millions" of resistors.
     
  7. mik3

    Senior Member

    Feb 4, 2008
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    I disagree with this circuit because if you don't use a resistor between the capacitor and the output of the first rectifier then the capacitor will discharge rapidly.
     
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