[sdiy] Proximity volume control.

[peter edwards]

I'm working on a series of synth podiums for a show coming up in a  
few months. I want the volume of each podium to increase as the  
viewer approaches it, or at least (worst case) to turn on when they  
are standing in front of it. I think a range of 1-2 feet is necessary.
I've been thinking about different methods. IR distance sensors or  
something of that sort could work but would require lots of  
processing hardware. I think that capacitive sensing would work fine  
and would ultimately be the cheapest and easiest option. Thoughts?

I couldn't find schematics for "capacitive volume control" or  
"proximity volume control" so I started looking into "theremin volume  
control". This seems to be what I want, but I think theremin range is  
calibrated for approx 6"-1' right? I also want to set it so that the  
volume increases as the viewer moves closer and produces NO sound  
when there is no one standing close to the podium.
Has anyone else here worked with this kind of circuitry? I'm hoping  
there's someone here I could chat with for a few minutes. thanks!

-pete edwards
casperelectronics