Simple speed controller

[froggy]

Hi guys
As i discussed with some of you at RIAT..i have gone ahead with my robot frog project...pic attached..
As the frog will just hop in a straight line...(until i can figure out a way of steering it ) I need a simple speed controller...reverse not needed...R/C interface not needed just a simple pot controlled speed controller going from 0%....to 100% speed..
Motor to be controlled is a wheelchair 35 amp 300w spec....so i reckon 50 amp handling will be fine.
Anyone got something like this gathering dust in a shed ??

Cheers Froggy

[typhoon_driver]

http://www.technobotsonline.com/motor-c ... ators.html

Might be of some use?