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Sorry to disappear, I thought the site would email me when replies were posted. Anyway, I don't have any experience programming. I'm getting my masters in fine art, so I know a lot about welding and oil paint and all that, but this is my first foray into electronics other than simple wiring. After a lot of consideration I realized that it would be easiest to have the needle move in a full circle rather than up and down for the simple fact that there would be no direction change. I appreciate all the suggestions. If you're interested, images of the piece should be up in about a month at my website: www.jeffreythompson.org

I'm trying to figure out a simple way to have a motor, hooked up to a timer circuit, that will switch polarity at a set interval. In other words, after, say 3 minutes, the polarity going to the motor will switch, putting the motor in reverse, then after another three minutes switch back. I'm pretty much a novice, so any help with this would be great. It will be part of a sound sculpture for my masters thesis exhibition.

I'm a grad student at Rutgers University, working on my Masters in Fine Arts thesis show, and would like to build a piece that is nearly fully developed, except for one key part. I'm building a sculpture that "plays" the paint-roller texture of a wall. A small plastic needle runs down the wall. Attached to this needle is a contact microphone that picks up the sound from the needle, kind of like a record player. What I would like to do is have the signal from the needle modulate the volume of a sine tone (coming from a separate source). I would prefer a hardware solution (ie: circuits, effects pedals, etc.) rather than a software one. I know this could be acheived using MAX/MSP but I dont' really know the program and don't want to have a dedicated computer just for this project if I can avoid it. The only other idea I had was some kind of modified envelope follower that took two inputs and modulated one based on the other. I'm totally stumped. Any suggestions?