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Forgot the name of this circuit (description inside)

  1. Apr 4, 2013 #1
    A circuit that measures two resonant frequencies and compares them with an LM741. One 555 is a metal detector with a coil of wire, and the other 555 is to be matched in resonance.

    Any idea what the name of this circuit is? I thought it was an OP Amp differential amplifier, for metal detection, but as you can imagine double checking that on google is a little difficult
  2. jcsd
  3. Apr 4, 2013 #2


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    Science Advisor

    That would be a mixer.

    The two oscillators produce an output above the limit of human hearing, but when the two mix, the difference frequency is audible.
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