[sdiy] Proximity volume control.

[Richard Wentk]

On 28 Nov 2009, at 12:50, peter edwards wrote:

> 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?

Sharp's IR distance sensors produce a clean voltage between 0.5V-3V, and require almost no processing at all. 

Add a buffer, with optional level shifting and maybe some linear scaling, and you're done.

See e.g. 

http://www.sparkfun.com/commerce/product_info.php?products_id=242

Richard