knutson@Utexas-11@sri-unix (12/04/82)
I was at a science show a few years back and had a chance to play with some field sensing equipment that would produce varying tones according to the placement of an object within the field. Does anyone know how I can get a hold of these things and how much they cost? Has anyone tried interfacing them as input devices for a computer? -------
jfw (12/05/82)
What you are talking about sounds like a good old Theremin. A Theremin is basically an RF oscillator with an antenna connected to the tank circuit, which picks up body capacitance from the 'musician' and varies the frequency (one plays it into a radio which has a local oscillator, generating a beat frequency which is varied according to the varying capacitance). If you know how to build a simple RF oscillator, they are easy to make (I think they work best with tubes, due to the high intrinsic capacitance of most transistors; my information on that may be out of date, though). Poke through your local library for 1960's vintage "101 Easy Electronics Projects" style books; that is where I saw a Theremin for the first time. John Woods, WB7EEL/1 ...decvax!mitccc!jfw (you are lost in a maze of twisty little uucp paths) Jfw@Mit-Ccc@Mit-Mc (until the TCP/IP mutants take over)