Re: Electric from radio??


"sensible" <flantoons@xxxxxxxxxxxxxx> wrote in message
news:3d65a59d-ed19-4443-b908-b47d6f430bd4@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
Can anyone tell me whether you can get electricity from received radio
waves, please?
See this video...it has an antenna attached to a circuit of capacitors
and other stuff, and gets out volts from the other end....Does this
work? And if so, how does it work?

Thanks.

http://www.metacafe.com/watch/915226/free_electricity_from_thin_air/

simple answer yes but the efficiency is really low. There was described a
unit in Hobbies Illustrated some 40 years ago that basically was a glorified
Xtal set with 2 tuners - one was a narrow band superheterodyne unit that
you tuned to the strongest local AM radio station - that signal was detected
and rectified to produce a small DC voltage to "power" a small transistor
that feed a pair of headphones. The other tuner was a wide band TRF unit,
for good quality, and this tuner was the one you used to select the station
you wanted to listen to... I built one from a kit supplied by a company
called Radio House in Sydney Australia as a student project. pretty basic
and it did work quite well. I might even have the circuit in my archives -
very simple but whilst you can get usable voltage from a RF signal this way
the current or amperage is next to nothing so it will really only work with
voltage driven devices - loudspeakers would be out of the question.


.

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