Clapper Circuit

Discussion in 'The Projects Forum' started by AdamPrulhiere, Dec 1, 2009.

  1. AdamPrulhiere

    Thread Starter New Member

    Nov 12, 2009
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    I am trying to build a simple clapper using this schematic. http://www.instructables.com/id/EM92NOB662EP286OAF/
    Should pin 4 on the opamp go to 0V or -9V? I do not have the specific model number for the microphone I am using, it is an omnidirectional condenser microphone element from radioshack. The way this is wired, the output of the microphone is always 9V, is this right? Thanks!
     
  2. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    -9v/GND/battery return.

    If you are measuring between R1 and the microphone, you may very well measure 9v.

    I find the schematic very hard to read due to the colors used.
     
  3. AdamPrulhiere

    Thread Starter New Member

    Nov 12, 2009
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    0

    Okay thats what I thought. When I clapped near, spoke into, blew on the microphone there was no change in the voltage, it just stayed at 9V
     
  4. Audioguru

    New Member

    Dec 20, 2007
    9,411
    896
    You need an electret microphone, not a condenser microphone.
    Radio Shack knows nothing about electronic parts. Their poor quality parts might not work.

    An electret mic draws about 0.5mA so its voltage should be abour 4V when powered through 10k ohms from a 9V supply.
     
  5. AdamPrulhiere

    Thread Starter New Member

    Nov 12, 2009
    14
    0


    Thank you!
     
  6. CDRIVE

    Senior Member

    Jul 1, 2008
    2,223
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    Beware! That circuit does not have a protection diode across the relay coil. The parts list is also riddled with typos.
     
  7. Wendy

    Moderator

    Mar 24, 2008
    20,764
    2,534
    There was an older thread about a year ago about the same subject. I think that gentleman may have worked the bugs out, it might be worth searching for it.
     
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