Audio boosting circuit help

Discussion in 'General Electronics Chat' started by Razor Concepts, Jun 25, 2009.

  1. Razor Concepts

    Thread Starter Active Member

    Oct 7, 2008
    212
    1
    Here is a circuit that boosts audio levels to 0-4v.
    http://macetech.com/vuinput01big.png
    What I do not understand is why the battery is connected to the non-inverting input of the op-amp. I breifly tried this setup with my mp3 player and I nearly fried it :eek:
     
  2. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    Where do you see such a connection? The non-inverting input is attached to the common point between R5 & C2.
     
  3. Razor Concepts

    Thread Starter Active Member

    Oct 7, 2008
    212
    1
    There is that circular symbol labeled V2, is that a voltage source?
     
  4. Audioguru

    New Member

    Dec 20, 2007
    9,411
    896
    The circuit is wrong because it has nothing to limit the negative swing of the input signal. If the input was changed to be an inverting amplifier then a negative input swing would be allowed.
    If the existing circuit used an additional negative power supply then it would work fine.

    EDIT:
    Audio booster? No.
    It is a peak detector circuit with a DC output.
     
  5. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    Must be why the output feeds an ADC.
     
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