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Q: Finding resonant frequency

Discussion in 'Misc Electronics' started by Peter Lowrie, Dec 7, 2003.

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  1. Peter Lowrie

    Peter Lowrie Guest

    Hello me again...Darn it.

    This question is about finding the resonant frequency of a piece of
    stainless steel. Wondering if there were formulae for this purpose I did
    some searches in Yahoo and Google but, alas turned up nothing.

    The piece of stainless is a 14swg perforated disc measuring 80mm in
    diameter.

    I hung it up by wire and recorded the sound it makes by tapping with another
    piece of solid stainless, looped the sound file and attempted to measure it
    with fft anaylsis but with disappointing results.

    Who has bright ideas on methodology to accomplish a result?

    Thank you for your indulgence.

    PEL.
     
  2. CWatters

    CWatters Guest

    You have the right idea but I would feed to output of the microphone into a
    spectrum analyser. Look for peaks.

    Another way might be to mount a small directional speaker next to the plate
    and feed it with a sine wave. Bounce the sound off the steel into a
    microphone. Ramp the frequency and look for the power _absorbed_ by the
    steel plate. This should be a max at resonance..
     
  3. --
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    ###Got a Question about ELECTRONICS? Check HERE First:###
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  4. DaveC

    DaveC Guest

    Peter,
    I can't picture this. A coil attached to amplifier driven by sweep gen.
    What's the "terminal"? How is it attached to the disc? Is this like a speaker
    voice coil? You just drove a magnet or piece of metal attached to the disc?

    More details, please.

    Dave
     
  5. Spajky

    Spajky Guest

    get a guitar, kick the disc with a stick & compare the sound, when you
    find exact tone it matches to a guitar tone (or piano tone) - basic
    tone, not harmonics! than go to my site to se a tone frequency chart
    under electronics/fan stuff 3 second page ... :)

    -- Regards, SPAJKY
    & visit site - http://www.spajky.vze.com
    Celly-III OC-ed,"Tualatin on BX-Slot1-MoBo!"
    E-mail AntiSpam: remove ##
     
  6. If you drive an unmagnetized core coil with an AC current from an amp,
    the lack of magnetization will cause it to put out a very non-linear
    magnetic field. It would be better to superimpose the AC on a DC
    current so that the DC current causes the coil to stay magnetized for
    the full AC cycle.

    I built one of these with the 'I' laminations removed from the core of
    an audio output transformer. I turned the steel side of a washing
    machine into a speaker.

    --
    @@[email protected]@[email protected]@@[email protected]@[email protected]@[email protected]@@[email protected]@[email protected]@[email protected]@,@@[email protected]@[email protected],@@[email protected]@[email protected]@[email protected]@
    ###Got a Question about ELECTRONICS? Check HERE First:###
    http://users.pandora.be/educypedia/electronics/databank.htm
    My email address is whitelisted. *All* email sent to it
    goes directly to the trash unless you add NOSPAM in the
    Subject: line with other stuff. alondra101 <at> hotmail.com
    Don't be ripped off by the big book dealers. Go to the URL
    that will give you a choice and save you money(up to half).
    http://www.everybookstore.com You'll be glad you did!
    Just when you thought you had all this figured out, the gov't
    changed it: http://physics.nist.gov/cuu/Units/binary.html
    @@[email protected]@[email protected]@[email protected]@[email protected]@[email protected]@[email protected]@@[email protected]@[email protected]@@[email protected]@[email protected]@[email protected]@[email protected]@[email protected]@[email protected]@@
     
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