window comparator using a single op-amp

Discussion in 'General Electronics Chat' started by harry, May 8, 2005.

  1. harry

    Thread Starter New Member

    May 8, 2005
    2
    0
    the usual design of a window comparator uses two op-amps...does anyone one have a circuit for a window comparator using a single op-amp...i badly need it for my research..tnx
     
  2. pebe

    AAC Fanatic!

    Oct 11, 2004
    628
    3
    If there fixed limits to the window, it can usually be done using positive feedback to give hysteresis.

    BTW, you needn't post on two forums - people usually look at both, anyway.
     
  3. hgmjr

    Moderator

    Jan 28, 2005
    9,030
    214
    Here is a circuit that uses one opamp and a couple of diodes to implement a window comparator.

    If you are comfortable with the math then you can run with it.

    If you need help with setting the circuit up for your specific parameters then if you will supply me with

    1. Your power supply voltage
    2. Your two window voltage limits

    I will take a stab at selecting the components to suit your application.


    [attachmentid=631]
     
  4. pilko

    Active Member

    Dec 8, 2008
    213
    20
    Hi
    I'm new to this forum Can you explain how I locate the attachment.

    Thanks
     
  5. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    You're better off using comparators than opamps. An LM393 (dual) or LM339 (quad) comparator can be wired as a window comparator. Opamps are not a good choice for window comparators as their outputs would be in constant saturation, causing heat and wasting power.

    Have a look at Rob Paisley's comparator page:
    http://home.cogeco.ca/~rpaisley4/Comparators.html
    There's a window comparator about halfway down the page under "Voltage Window Detector Circuit"
     
  6. flat5

    Active Member

    Nov 13, 2008
    403
    17
    "I'm new to this forum Can you explain how I locate the attachment." The attachment was posted in 2005. It is not to be found on that site anymore :) and I cannot format my text. This editor sucks.
     
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