This will show a racers speed at a point on the hill using two small lasers 20cm apart on one side of the road, receivers on the other to a display using 6.5" LED 7 segment displays (can get up to 20"). The system is adapted from a scale system made by a small educational company for timing Scalextrix, but we are upscaling it for the real world. Should be fun. Should be interesting to clock some speeds. Our system will likely ditch the word 'speed'.
Photos of the system in use at a school, and the 7 segment display.
