Measure 40-Yard Dash with Lasers, Phototransistors, and Lots and Lots of Wire

With the NFL season just around the corner, hundreds of athletes are getting prepared. Players range from humongous linemen who sacrifice speed for strength; to defensive backs with incredible speed — but stereotypically bad hands — to wide receivers who are quick, agile, and can pluck a ball out of the air with the greatest of ease. One important measure of a player’s speed is the 40-yard dash, with a 4.4 second time considered excellent, and a few who can even run faster. In celebration of the upcoming season, software/hardware collective “Flopperam” decided to make their own DIY run timer.

The device uses a Raspberry Pi for control, with sensors arranged at the start and the end of the race, and a trio of very long (~40 yard) wires connecting the two. After initially attempting to use laser pointers aimed at photoresistors as break-beam sensors, they eventually changed to phototransistors for better “high speed” performance with the lasers. This necessitated the use of an ADC board to compensate for the Raspberry Pi’s lack of analog pins, and they switched from ambient light shielding made out of paper cups to a somewhat heavier packaging materials.

Code and more info is available on GitHub, and while the build was successful electronics-wise, the fastest time ran so far was a 4.78… with a moving start. As none of Flopperam group appear to be ready for a lineman role, they’ll likely need to rely on crisply executed routes in a slot receiver role, and presumably superhuman hand skills to earn a roster spot. Check it out in the video below, and if you’re wondering, the 40-yard dash world record is 4.12.