Precision Rectifier and Peak Detector

Discussion in 'General Electronics Chat' started by Nevermored, May 30, 2012.

  1. Nevermored

    Thread Starter New Member

    May 30, 2012
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    Hi,

    I'm working on a project right now where I need a precision rectifier and a peak detector. For the precision rectifier, I was planning on using a diode and op-amp. For the peak detector, I'm a little confused. I've a some Googling, but I'm not sure how to design the peak detector. Sensitivity is a BIG issue, I need it to be pretty sensitive. 0.05V-0.1V at low frequencies not exceeding 60Hz.

    I attaching the two circuits I was thinking of implementing. I'm not sure how to modify them for my specific purposes?

    I was also thinking of this http://freecircuitdiagram.com/2008/09/07/precision-half-wave-peak-detector/ which claims to be precise under 100mV, but it uses a LF351 which appears to be discontinued.
     
  2. PaulEE

    Member

    Dec 23, 2011
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    What's your question?

    I've messed about with precision rectifiers. They're not as straightforward as the pretty schematic you uploaded.

    Can you reveal a bit more detail as far as what you're aiming to do with all these devices? That'll give us a better clue as to what your options are.

    Paul
     
  3. t06afre

    AAC Fanatic!

    May 11, 2009
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  4. MrChips

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  5. Audioguru

    New Member

    Dec 20, 2007
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    Nevermored,
    You attached a very bad circuit.
    The first circuit has nothing to discharge the capacitor so it will not work properly.

    All opamp circuits in this thread do not show how the opamps are powered. Most of the circuits need a dual-polarity power supply.
     
    Last edited: Jun 4, 2012
  6. bountyhunter

    Well-Known Member

    Sep 7, 2009
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    You can have this one I designed some years back for a wide band (about 20 - 200 kHz) AC meter. The circuit shown creates a negative voltage, just reverse the polarity of the diodes if you want a positive output. Use both 1N914 diodes if you only want low frequency performance. I used a current source (not shown) to discharge the peak hold cap (the 1uF cap). Add a big resistor across it for discharge such as 2 MEG or similar.
     
    Last edited: Jun 4, 2012
  7. crutschow

    Expert

    Mar 14, 2008
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    The "Superdiode" circuit does have the diode inside the feedback loop, so I don't understand your statement. :confused:
     
  8. Audioguru

    New Member

    Dec 20, 2007
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    OOps, yes you are correct. I looked at it too quickly.
     
  9. BMorse

    Senior Member

    Sep 26, 2009
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