The link below is to an open source Brushed Perm Mag DC motor controller.
http://www.theworkshop.ca/energy/picox/4/picox4.htm
the brd has been bench tested against a Locked Rotor upto 48V/75A peak, 48V/50A cycled, and numerous 60 Sec 48V/25Amp current limited runs.
The controller is based around a simple PicAxe 08M class ucontroller with ADC (Analog to Digital Conversion) on the throttle and Current sense hardware with software programable Current Limiting.
FrankG
www.theworkshop.ca
frank@theworkshop.ca