Reply to Dumb hacks (#1 in a series of many)

Strap one of these:

http://literature.agilent.com/litweb...988-1853EN.pdf

to the tone arm of a deck (or on the side of the platter pointing at the rim), wire to an Arduino, print out a busy pattern to stick under it, send relative MIDI messages based on the quadrature output (oh just google it).

Voila, relative motion MIDI controller. Sorry, no absolute positioning, but you can scratch for under $20 in parts. Cheaper if you get the chip and lens from a retired mouse.

- Fatlimey.