I have recently pulled apart two old RC helicopters for their parts and built an RC car out of it. It is pretty basic, and uses the servo motors, motors and the receiver from the helicopter, and I control it with the controller that came with it. It works fine, except for an excessive heat build up in the control circuit with the receiver. In fact, a part of the circuit started glowing orange and smoke billowed out. I tried it again after it had cooled down to see if it worked, and the steering through the servo motors still works, but the motors that make it go forwards no longer works. I have put the control circuit from the second helicopter in my RC car now, and I don't won't to ruin it. So I have been very careful, and have noticed that it builds up a fair bit of heat after 10 seconds of driving. The motor makes a high pitch whining sound, which I'm guessing is from the speed control, but it has a range of current going through it where it starts whining, but isn't moving. Does this mean that all of the power going into it is converted to heat and sound? If so, that could be the problem. The only changes I have made to the motors is removing the gear that the motor drove - the motor had a small gear that drove a large gear, making the helicopter blades spin slower. So I removed the large gear, could that be a problem? Do I need a control circuit that can handle more current, or is there a problem with the motors? It worked fine in the helicopters. The component that is no charred from the original circuit was an IC of some kind, I believe the motor's speed control. Thanks for any help. --Short version: The circuit that my motor is connected to gets hot, I believe the problem might be when current goes through the motor, but not enough to make it spin, but enough to make noise. So the energy is being converted just to heat and sound. I think it is the motor's speed control that was burnt out in the original circuit.