This was made as a plug-in replacement upgrade for the horrible capacitor popping controller found in the Hot Wheels slot car sets from Mattel.
- It doesn't break if you short circuit a track.
- Actual speed control, you can now go smoothly from still to full speed, instead of "still, jump to 70%, smooth to 100%".
Two self resetting poly-fuses limit the current to 500mA per car, at 12V this should be enough for most 1:24 cars. I use 9V for the Hot Wheels circuit.