Seeking suggestion for Mic & Preamp

Discussion in 'The Projects Forum' started by JDC, Jun 29, 2009.

  1. JDC

    Thread Starter New Member

    Feb 29, 2008
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    0
    I seek a circuit suggestion for the following application:

    I want to place a small microphone on the outer surface of a pipe adjacent to a zone that has turbulent flow of liquid moving through it, i.e. the microphone serves as a stethoscope.

    I seek a suggestion for a microphone selection and preamp circuit powered by 5VDC, with an amplified output of the microphone input, i.e. 0 to about 5volts. I wish to send the pre-amp output to a frequency counter. I will [later] correlate the frequency to volumetric flow rate of liquid through the pipeline. I do not care much about waveform. I simply want to have a 0-to-5 volt AC output that feeds my 0-to-5 volt pulse counter.
     
  2. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    The Wikipedia article - http://en.wikipedia.org/wiki/Contact_microphone - is hardly definitive, but the microphone type is probably more suited to your interest.

    Besides using some similar device, you might consider a bit of experimentation before going to a final design.

    Be aware that it is quite trivial to reduce a higher voltage waveform to a 5 volt level. Don't start off blocking all paths but one.
     
  3. JDC

    Thread Starter New Member

    Feb 29, 2008
    3
    0
    Thank you beenthere,

    It seems that a piezo contact microphone element, whose output is sent to a 5VDC-sourced comparator input, may cause the comparator output to be a 0 or 5VDC output depending on the presence, or absence, of vibration acting on the piezo element, true?

    The comparator output may be received by a pulse counter.
     
  4. beenthere

    Retired Moderator

    Apr 20, 2004
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    I would want to characterize the signal before proceeding to final design. The contact mic is probably one of the devices that are suited to your application.
     
  5. DickCappels

    Moderator

    Aug 21, 2008
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