Beat the Clock on This Arduino Flying Start Lap Timer

Richard Garsthagen is the owner of a Razor Crazy Cart — a toy vehicle that lets you drive, spin, and drift like a pro right at home. The only downfall of having just one is that he was unable to race against others. So in true maker spirit, he decided to come up with a solution that would still allow him to be competitive: a flying start lap timer.

The lap timer is based on an Arduino Uno and uses a Velleman PEM 10D infrared light bridge to detect when something crosses the line, two Adafruit 7-segment displays to show the time and lap count, and a SparkFun thermal printer to spit out the final results. The frame itself is constructed out of MakerBeam components, while power is supplied through an 11.2V LiPo battery.

The system also has a few buttons (race, menu, and select), a pot-meter to set the number of laps (one through nine), and an on/off switch. Simply click the race button to get things underway. Since it uses a “flying start” principle, there’s no countdown. After crossing the line once, the timer begins and will proceed to display the number of laps to go on the top 7-segment display along with the time on the display below.

So what can you use this lap timer for…. well anything when you want to be competitive without directly racing another person. We have use it for our crazy cart, running and cycling around the house… As long as you position the light brige sensor correctly, you can have a lot of competitive fun! The sensing range of the PEM10D is 33 feet, so you can really have a big start/top line.