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Microphone Help.

  1. Oct 6, 2011 #1
    I have a circuit that can take the input from microphone and amplify it with OPamp. I have connected everything correct and when i check the output whit no input at microphone still i get output with constant amplitude. I think that was due to gain of OPamp but not sure. The opamp gain is 500 and when if there is any input(song or sound) at microphone it just following the song. Please clear me why i am getting these constant amplutude when there is no input. Is this really due to gain. Please see the image when there is no input.

    Attached Files:

  2. jcsd
  3. Oct 6, 2011 #2


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    Staff: Mentor

    Looks like 100Hz (or 120Hz) noise from rectified AC Mains noise. Are there flourescent lights nearby?
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