|MadSci Network: Engineering|
Hi Glenn. Always glad to talk to friends on the Canadian Shield. The answer is no, but perhaps someone more creative than me can contrive a way. It doesnt sound like a good approach, anyway. We try to do as much as we can electrically and as little as possible mechanically. Moving brushes onto and off a commutator doesn't appear easy. Average voltage is what controls DC motor speed. This is best done with pulse width modulation. Hobbyist magazines have these circuits. Also, kits from ads in these same magazines show speed control including motor for under $20 US. Sorry I can't help more. Larry Skarin
Try the links in the MadSci Library for more information on Engineering.