Racing slot cars can be fun, but knowing who’s fastest when requires precision measurement equipment. Enter, an Arduino-based lap timer. The timer detects the cars using an infrared beam and records the lap time. For each track, the best lap of a race and the time for the last lap are shown.
As the timer is aware of the concept of a race, it also provides race start lights. Something that really adds to the atmosphere. The link above not only provides schematics and software – the end result is a impressive model landscape.