From: Phil Osborn (philosborn2001@yahoo.com)
Date: Sat Apr 13 2002 - 16:55:18 MDT
A few years ago, I took a big sub-woofer and connected
the input leads to an LED. Sure enuf, you bang the
speaker and the LED lights up. Put enough of these
speakers by a freeway with a full-wave bridge
rectifier on each one and you could get some
appreciable power, although it would still be very
inefficient, as the speakers are not optimzed to work
as generators.
Similarly, on at least two independent occasions, I've
met people who invented RF powered radios for their
own use. One guy was an Air Force Mechanic in the
Czech military. He disguised his radio as a hearing
aid. It had two tuning circuits. First you tuned the
power circuit to the strongest source you could find.
Then you tuned the listening circuit to whatever you
wanted. He said he used to listen to BBC and Radio
Free Europe all day long and no one suspected a thing.
The other guy was a neighbor of mine who repaired
TVs, etc., for a living, back in the early '60's. He
essentially did the same thing, just to see if it
would work. In most urban areas there is quite a bit
of broadcast power passing through every cubic meter
that currently dissipates to entropy.
There is quite a lot of sonic vibration out there as
well, man-made or otherwise. So, how to optimally
design a system that tunes itself to either transient
or continous harmonic vibrations?
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