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Current drain of typical electret mic?

Discussion in 'Electronic Equipment' started by Sandi, Feb 23, 2006.

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  1. Sandi

    Sandi Guest

    What is the current drain of a small electret mic similar to this:

    http://www.maplin.co.uk/images/full/27416i0.jpg

    Am thinking of the sort which takes an internal silver oxide battery
    and is mono.


    Would a mic like this draw a current when it is not plugged in and
    not being used?
     
  2. Robert Baer

    Robert Baer Guest

    I do not know of any that use a battery inside; all of those i have
    seen get power from the instrument (like the stereo mike input on a
    computer - one side is sound and the other side is the power).
    In any case,the power is in series from source to mike - meaning if
    the mike is disconnected, no current would flow.
     
  3. Here is one with a battery inside:
    http://www.maplin.co.uk/Module.aspx?ModuleNo=27416&criteria=electret &doy=23m2

    Individual designs vary - those that take power from the line clearly do
    not do so when disconnected. Those with internal batteries typically do
    take power whenever switched on. A standard, capacitor-coupled amplifier
    input would not provide a path for the DC power.

    Some amplifiers have internal links to provide power for electret
    microphones, over the microphone lead. Many do not.
     
  4. Setanta

    Setanta Guest

    electrets should not draw any power when not plugged in

    Phantom power is a 48v signal from your desk
     
  5. TimPerry

    TimPerry Guest

  6. Zak

    Zak Guest


    You are referring to mics with Plug-In-Power or those with
    phantom-power. Other mics have the battery inside.
     
  7. bob mcree

    bob mcree Guest

    the batteries in a typical electret mike usually last several
    years. the draw is so low it is the shelf life of the batteries
    that matters. they self-discharge internally with time.

    -bob
     
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