I just found out about them a week ago. First Query: Would it be possible to insert one into someone's clothing (So it wouldn't be noticable to them) to hear things like subvocalizations or other bodily noises, etc.? Second Query: What kind of power source do they need? I've heard some RFID's can run on the power of the human body itself. Thankis for any replies.
-Josh
Maybe... This is more on mechnaical design than electronics problem.. Piezo disks are used for example to pick up sounds from surfaces, for example from some musical instruments.
Piezo discs when used as microphone do not need any power source. They are passive devices that convert mechnical forces applies to them top electrical voltage output. When you hit/bend etc.. the disck then you get voltage out. The voltage is stonger the more force you apply.
-- Tomi Engdahl (http://www.iki.fi/then/) Take a look at my electronics web links and documents at
You have to have a way to mechanically couple the microphone type device to the person's body. What you wan to hear is at a very low level, and would require a lot of amplification. This will be difficult. You will also have the problem with the environmental noise.
The output levels from these piezzo disks is very low. They need some type of force against them in order to generate some output. If is the sensor type, these are not very responsive to sounds. They are designed to pickup vibrations, and changes in mechanical pressure. If you are thinking of any type of power from them, it is going to be only a few microvolts. This level of supply is really useless for any practical means.
-- Jerry G. =====
I've never heard of that fetish before. What's it called?
Just an idea I had. It would be creepy to hear what someone else is reading...
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