In a preferred embodiment, a high-frequency, pulse-width-modulated, power-transistor, DC motor speed controller having current limiting in both drive and regenerative modes, essentially constant ramping rates regardless of whether or not the operator switches to neutral before changing direction, a simple...http://www.google.com.au/patents/US5261025?utm_source=gb-gplus-sharePatent US5261025 - Method and apparatus for DC motor speed control
