[sdiy] Circle Machine prototype

[Synthmanic at aol.com]

In a message dated 8/17/2010 7:58:21 A.M. Central Standard Time,  
controlvoltage at gmail.com writes:
On a related topic, a friend of mine made a  rather nice optical audio
transmitter-thingy using a dollar-store laser  pointer, power
transistor and phototransistor... used the power transistor  to
modulate the power to the laser with audio (input audio to base  of
power transistor), then aimed the laser at the phototransistor,  which
essentially modulated +VDC to reproduce the audio.  Worked quite  well!
I've wondered if there aren't any exotic materials you could pass  the
laser light through in order to get some sord of  optical-modulation
effects device.  Of course, delay would be out of the  question unless
you had a number of miles over which to set this  up...

(hey, how bout an analog delay that works by bouncing  audio-modulated
laser light off the Moon?  Sorry, too much coffee this  morning....)
 


Sounds like an updated version of  this:

http://en.wikipedia.org/wiki/Photophone


DW