Averaging opamp

Discussion in 'General Electronics Chat' started by Konstabel, Feb 17, 2008.

  1. Konstabel

    Thread Starter Active Member

    Jan 31, 2008
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    Is there something like an averaging opamp circuit? I have three voltages I would like the average of.
     
  2. hgmjr

    Moderator

    Jan 28, 2005
    9,030
    214
    Take a look here .

    hgmjr
     
  3. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    Yes there is:
    http://www.allaboutcircuits.com/vol_3/chpt_8/8.html
    Averaging/summing circuits utilizing op amps and "weighting" of inputs are explained on the page the link refers to.

    [eta] hgmjr, you must've beat me to the punch by all of two nanoseconds. ;)
     
  4. Audioguru

    New Member

    Dec 20, 2007
    9,411
    896
    An inverting opamp is a mixer and will add the input voltages.
    Then a divide-by-3 attenuator will output their average voltage.
    It is inverted so another inverter will correct the polarity.
    The second inverter can be the divide-by-3.
     
  5. cumesoftware

    Senior Member

    Apr 27, 2007
    1,330
    10
    If I understand well, you don't need an op-amp for that (except if you want to use a voltage follower next to the network). A resistor network should do the trick. You can connect the resistors from the nodes to be averaged to a common node. The common node will have the average voltage if the resistors are equal. This technique is used in stereo to mono converters used before the bass filter on an amplifier, in amplifiers that use only one subwoofer for both left and right channels.
     
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