Help identifying microphone components

Discussion in 'General Electronics Chat' started by glug, Apr 25, 2011.

  1. glug

    Thread Starter New Member

    Mar 29, 2011
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    There are two components in this "transformerless" M300 Gefell mic I'm curious about. What's that dome lookin' thing? In the 2nd and 3rd pic, there is another example from a different Gefell mic body (mv200). And also the rectangular package. I believe it is stamped 03YH017 09.94. My searches came up empty. Thanks!
     
  2. oidium45

    Active Member

    Apr 24, 2010
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    8
    Looks like it could be an oscillator but I cannot really tell.
     
  3. marshallf3

    Well-Known Member

    Jul 26, 2010
    2,358
    201
    Might also be a small enclosed filter but most likely an enclosed combination amp and impedance converter.
     
  4. glug

    Thread Starter New Member

    Mar 29, 2011
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    Thanks for the replies. So all of those things - oscillator, amp, impedance converter - are all somewhat akin to a transformer. I guess I'll send the mfg a note. Maybe they'll just tell me ;)
     
  5. Veracohr

    Well-Known Member

    Jan 3, 2011
    552
    76
    Did you look up info on the mic?

    One of the two (rectangular & circular) components is probably the optical coupler, the other an amp/impedance converter.
     
  6. glug

    Thread Starter New Member

    Mar 29, 2011
    6
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    That was helpful, thank you!

    I own a similar version of that mic, the MV200. It does not have the rectangular device. And I don't think it has the opto-coupler. So I'm guessing that is the OC. I'm curious how the opto-coupled power supply circuit would work.

    My mic does have a similar (but different) round device. Maybe that is part of the polarization voltage generator, or maybe something for impedance matching. Though using a 'coil' of any sort for impedance matching the signal does not seem consistent with a transformerless design. I haven't opened my mic up to trace the circuit.
     
  7. Veracohr

    Well-Known Member

    Jan 3, 2011
    552
    76
    I hope I'm not wrong and make a fool out of myself here, but...

    The quote I posted said "a very clever technique is used to power the circuitry and bias the capsule". I don't know everything I should about microphones, but I take this to mean that the capsule only needs a voltage bias, it doesn't need current. So the purpose of the optocoupler would be to electrically isolate the capsule by passing the signal voltage but not current. The rest of the circuitry would be before the coupler, and thus would be able to receive whatever current is necessary.
     
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