Condenser mic question

Discussion in 'General Electronics Chat' started by frenchie29, Dec 29, 2008.

  1. frenchie29

    Thread Starter Active Member

    Nov 28, 2008
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    How does the DC voltage travel when using a condenser mic? I know pin 2 & 3 carry the power and pin 1 returns it, but are pin 2 & 3 positive voltage ??
     
  2. beenthere

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  3. frenchie29

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    Nov 28, 2008
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    What about the path for electrons and protons?
     
  4. beenthere

    Retired Moderator

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    Protons? Electrons are the only charge carriers running around loose.
     
  5. frenchie29

    Thread Starter Active Member

    Nov 28, 2008
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    And they are running trough pin 2& 3?? What goes trough pin 1?
     
  6. beenthere

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    The terminology is tip, ring, and sleeve. I believe the sleeve (pin 1) is always circuit common. That is both the shield and ground reference.

    The ring (pin 3) is +5 volts. That places a charge on one side of the condenser element, which is basically a capacitor with a fixed plate (getting the +5) and a flexible plate that responds to the sound.

    the tip (pin 2) is for the signal. When the flexible capacitor plate moves under the influence of sound, the capacitance changes, and that causes charge to be driven off and onto the flexible plate. This becomes a varying voltage when developed over a resistor in the preamp.
     
  7. Audioguru

    New Member

    Dec 20, 2007
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    An old fashioned condenser mic is powered from 48V, not 5V. A new electret mic is wrongly called a condenser mic and it uses 0.5mA, not 5V.
     
  8. eblc1388

    Senior Member

    Nov 28, 2008
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    When using electret mic at different supply voltages, does this means the loading resistor value should be = 1/2 [ Vcc / 0.5mA ] or just Vcc/0.5mA?
     
  9. bertus

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  10. frenchie29

    Thread Starter Active Member

    Nov 28, 2008
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    That's a great site Bertus, thanks

    On a different note is there actual return voltage on pin 1?
     
  11. Audioguru

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    Most electret mics are spec'd with a current of 0.5mA. For a 2-wires electret mic the supply resistor/load resistor is at the drain of an internal JFET so the gain is affected a little by the value of the resistor.

    With a low supply voltage is is best to use a higher resistor value than is calculated so that the current is less than 0.5mA and the mic is not loaded down too much.
     
  12. frenchie29

    Thread Starter Active Member

    Nov 28, 2008
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    So is there actual voltage running on pin1???
     
  13. tumadre

    New Member

    Jan 5, 2009
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    No, there isn't. Pin 1 is ground. Phantom power is equally applied to the two signal lines, ie. Pins 2 and 3.
     
  14. frenchie29

    Thread Starter Active Member

    Nov 28, 2008
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    Isn't it pin 1 for return??? That's where I'm a bit confused The way I understand it is pin 2 & 3 carry power to the load and returns trough pin 1 to complete the cycle!! Am I way off???
     
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