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Output power of a microphone?

  1. Oct 18, 2007 #1
    1)right...well, a microphone converts audio signals into corresponding electrical impulses right.. I just want to know how much is the average output power of these things? and how much voltage can be achieved from them...

    2)Another question I have is, what kind of antenna do they use in a phone? I know its a monopole antenna and one can receive the signal irrespective of the orientation.. so what antenna do they use? I mean... I ripped apart a cell phone once(one that wasn't working of course.. :D), hoping to find the antenna inside... But I couldn't see anything resembling of what I expected, no single wire, no circular coil, no patch, no spiral... So what type of antenna do they actually use in these cell phones? and what do they look like? and whats their average size or area?

    3)If I had an antenna receive all the surrounding EM noise around me, what do you guys think would be the output power of this thing?

    4)And my final question... I used my hands and held the 2 ends of a multimeter with it and while holding it, I noticed that the multimeter showed .2 volts... So where is the voltage coming from? It can't be the output voltage of the body or something like that right? I mean shouldn't that be in millivolts or microvolts or something?
    Last edited: Oct 18, 2007
  2. jcsd
  3. Oct 18, 2007 #2


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    1) There are a number of different ways to make a microphone. For a general category microphone You might get a few millivolts at best with normal volume levels. However, special setups with high noise input can generate significant power.

    2) Don't know about your phone, but yes it might be hard to recognize the antenna if you don't know exactly what you are looking for. It could be imbeded in the case.

    3) In the microwatt area. Not what one would consider power.

    4) Probably chemical reaction of your skin with the metallic probe tips.
    Last edited: Oct 18, 2007
  4. Oct 19, 2007 #3
    hmmmm... first of all... thx for replying mate...

    Okay... If I used a piezoelectric microphone, how many millivolts would that produce? around lets say... .2 volts or around 200 millivolts?? Is that value too high?? Also how much would one cost?

    and ah... okay.. thanks for clearing up the other questions for me..
  5. Oct 19, 2007 #4


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