I've modified a piece of exercise equipment so that it generates 12v dc. Max current is almost certainly less than 1 amp (more than that, and the subject (exerciser) poops out fast). Standard (car lighter) plug allows any appropriate device to be powered. Current generation is being correctly monitored and reported graphically. All that seems to work just fine. What I'd like to add is an array of LEDs on the equipment itself, to provide real-time feedback/encouragement to the exerciser/subject. Something like 150 ma lights one, 300 ma lights two, 450 ma lights three, etc. Got absolutely no idea how to design that circuit. Any thoughts?