Hi, I'm taking parts from an old toy RC helicopter and turning it into an little car which can't turn. I want to use the tail fan as a turbo/air brake thing using the right gyro stick on the controller. I cut the power leads for the fan and replaced it with another powerful and bigger fan to see it it will work. Then I took a tip31 , attached the power leads coming from the heli board and attached the positive on the right leg and negative on the left (It might be opposite :$). I took the negative from a 9V battery and hooked it up to the negative part of the tail fan power lead. I attached the middle leg from the tip31 and attached it to the motor and attached the positive from the 9V battery to the new motor. I tested it and it only worked as turbo, no brakes . (I think you get what i'm trying to do here. Amplify the tail fan power leads to be compatible with the new motor.). I forgot about the reverse. Anyone got ideas? I have 6 tip31's in my box and I will use them if I have to .