Last christmas I bought a slot car racing track for my grandchildren.
But soon they complained about the missing lapcounter.
As buying one was not an option for an electronic engineer, I decided to build one on my own.
Of course this lapcounter should have some features:

• Displaying laps and laptime on a graphical display
• Beacon for starting/stopping the race
• Additional buzzer
• Controlling of the race with an (optional) Android-Smartphone via bluetooth connection