My living space has constant supply of a variety of annoying sounds thanks to a lack of proper sound deadening. I was wondering what is the practicality of creating an energy "leech" array using microphones? my current circuit that I am thinking of is using a lav-mic, slapping a full bridge rectifier across the output. That feeds into a small ceramic capacitor for some semblance of smoothing. Five of the previously mentioned would be wired in series and feed into a 5v supercap and then a joule thief will step up the voltage to 5v and will be fed into a li-ion battery management (charge/discharge circuit like the ones found in battery banks). I was thinking if there is such annoying noises might as well put them to use.

TL;DR: Is it feasible to create a low-power generator from microphones to harvest power from annoying noise sources?

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    \$\begingroup\$ Well, surely you can convert air oscillations into electricity. But I doubt it will be enough to power like anything. \$\endgroup\$ – Eugene Sh. Feb 25 at 19:11
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    \$\begingroup\$ Your microphone will hardly forward bias a diode and the diode will absorb most of the energy. Look up energy harvesting techniques instead. Typically you need significant levels of vibration to cause a significant mass to vibrate. \$\endgroup\$ – Transistor Feb 25 at 19:12
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    \$\begingroup\$ TL/DR : Not worth it. \$\endgroup\$ – user_1818839 Feb 25 at 19:14
  • \$\begingroup\$ There is not much power in this noise. I would imagine some sort of optimized speaker that could be useful- membrane, magnet on a weak spring, a coil. The whole thing must be mass-produced and used as a filler in walls. I don't know, seems much more complicated and expensive than just proper isolation. \$\endgroup\$ – Gregory Kornblum Feb 25 at 19:17
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    \$\begingroup\$ A large speaker will pick up lower frequencies and output a low-impedance signal. A transformer can step this up to a voltage you could work with. \$\endgroup\$ – hacktastical Feb 25 at 19:28

How about some numbers?

  • 0.775 volts into 600 ohms is one milliwatt.
  • A blue LED needs 3 volts and 20 milliamperes. That's 60 milliwatts.
  • If you collect energy at 1 milliwatt for 60 seconds then you will have enough energy to light that blue LED for one second.
  • Typical microphone output levels are about 1/1000 of one milliwatt.
  • It would take about 60000 seconds (nearly 17 hours) to collect enough energy to light the LED for one second.

Keep in mind that all of those numbers are optimistic estimates and that they assume that you can store all collected energy without losses and that you can convert voltages without loss.

There is no way that you can collect a useful amount of energy with a normal microphone in a normal home.


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