What is the Output Power of a Piezoelectric Microphone?

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Discussion Overview

The discussion revolves around the output power and voltage of piezoelectric microphones, as well as related questions about antennas used in cell phones and the voltage readings from a multimeter when held by a person. The scope includes technical explanations and exploratory reasoning regarding audio signal conversion and electromagnetic noise reception.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants inquire about the average output power and voltage of piezoelectric microphones, suggesting values around a few millivolts to potentially 200 millivolts under certain conditions.
  • One participant notes that the output voltage of a microphone can vary significantly based on sound loudness.
  • There is curiosity about the types of antennas used in cell phones, with suggestions that they may be embedded in the device's case, making them difficult to identify.
  • Another participant estimates that the output power from an antenna receiving ambient electromagnetic noise would be in the microwatt range.
  • One participant speculates that the voltage reading from a multimeter held by a person might result from a chemical reaction between the skin and the metallic probes.

Areas of Agreement / Disagreement

Participants express varying estimates for the output voltage of piezoelectric microphones, indicating a lack of consensus on specific values. The discussion about antennas and voltage readings also reflects differing levels of understanding and recognition of the components involved.

Contextual Notes

The discussion does not resolve the specific output voltage of piezoelectric microphones or the exact nature of cell phone antennas, highlighting the need for further exploration and clarification on these topics.

The_Thinker
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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 what's 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:
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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.
 
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hmmmm... first of all... thanks for replying mate...

Okay... If I used a piezoelectric microphone, how many millivolts would that produce? around let's 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..
 
The output voltage depends on how loud the sound is.

This link is the first thing that came up in Google for piezoelectric microphone
http://mysite.du.edu/~jcalvert/tech/microph.htm
 

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