You want to slot race, but have nobody who wants to play with you? Then why don´t you race against an Arduino? This Arduino Sketch makes it possible.
First of all, glue strong magnets to the slot car's wheels and arrange hall sensors around the track that signal the Arduino, where the car actually is. The arduino sketch then accelerates or brakes the car accordingly.
Because of these modifications, the hall sensors send impulses to the microcontroller whenever the car passes by. So the Arduino program knows, where the car actually is and accordingly decides about its speed.
Hall sensors are small electronic parts that detect magnetic fields. Whenever a magnet comes close to such a sensor, it pulls its output pin to ground, and can so be used as a kind of magnetic switch.
The Arduino's analogWrite() function generates a PWM signal which is amplified by a small transistor circuit and then put on the track. So the speed is set from whithin the Arduino program. With the function analogWrite() called with a parameter value between 0 and 255, every speed value between stop and full speed can be set.
And here is a brief explanation about how the sketch works: Every time when the slot car passes by a hall effect sensor, an Interrupt routine is being called. There the hall sensor which caused the interrupt is identified and a speed value is read out of an Array and brought to the red car by the analogWrite() command and the transistor circuit. Have fun!
See video: https://youtu.be/rkMEo5EV-iw