Control the speed of any common DC motor rated up to 100V (7A). Operates on 5V to 15V. Uses NE556 to pulse-width modulate a IRF530 MOSFET. In this way motor torque is maintained. Adjustable speed control. Box mounted.
October, 2003: Changed the MOSFET to an IRF530 so 100V motors could be used. But do not draw more than 7A thru the PCB tracks unless you thicken them.