idea
Bill Perry ( wperry3092@worldnet.att.net )
Tue, 14 Apr 1998 17:08:11 -1000
I checked out the URL for the Acoustic Compressor, and It reminds me of
an idea which I had a few months ago, sorta along the same lines but
without need of a compressor. It basically involves an insulated
container (the refrigerator) with an array of acoustic transducers and
microphones every 3-4 centimeters or so apart along the inside of the
walls. The microphones were to be of a type which used a laser-diode
type pickup which was to be modulated by about 30KHz, bounced off the
wall, and is reflected back. The signal that is picked up would be
compared with the original 30KHz and the resulting doppler shift would
be an exact match of the frequency coming off of the wall. In the
meantime, the same signal which is picked up from the laser-diode pickup
would be amplitude demodulated to create another reproduction of the
noise in the refrigerator. Keeping in mind that the doppler-reproduction
would be independent of the amplitude of any noise heard in the box, any
sound from the smallest click to the biggest hum would be of the same
amplitude when reproduced. Now for the doozy. The doppler-signal is them
fed through a comparator along with the amplitude-signal, which will
effectively block out all larger amplitude signals and all smaller
signals will be passed on, the processor circuitry would automatically
control the gain of the amplitude demodulator until only one frequency
is left at the output end of the comparator, which will thusly be the
resonance of the refirgerator box itself. Now the resultant frequency
(resonant) will be fed through an inverting amplifier (Class A) and
output from the transducer, which will effectively cancel (or severely
reduce) the resonant frequency at that part of the wall. This would
effectively cause molecular motion to slow (obviously it wouldn't stop
or that would be absolute ZERO) considerably, thusly absorbing molecular
motion from inside the box, cooling the contents.
BillP