stopwatch and roll
a timing problem
A fraction of a second can separate a personal best from a missed goal. But with a traditional stopwatch, the final time depends on more than the athlete. It also depends on the reaction speed of the person pressing the button.
A small delay. A real difference.
I saw this problem repeatedly while coaching runners, triathletes, and ultramarathoners. An athlete would cross the line—and a moment later, the stopwatch would stop. That tiny delay might feel insignificant, but in competitive training, hundredths of a second matter.
lightspeed presision
Instead of asking someone to react at the perfect moment to start or stop, I built a fully automated stopwatch that reacts to the athlete. Using two ultrasonic sensors to automatically start and stop the timer as the runner passes, turning an athletes movement itself into the trigger itself.
Every start is different.
This one understands both.
Some athletes launch from a standstill. Others enter at full speed. By requiring both sensors to activate, the device can recognize stationary and running starts while helping prevent accidental triggers. The sensors are equipt to recognize direction and pace making it ideal for track & field courses and other closed loop distance events.
TECH SPECS
The technology behind the time.
Twin ultrasonic sensors emit rapid subsonic pulses and measure their return, creating an invisible timing gate around the athlete. When both sensors detect the first pass, an Arduino micro processor begins counting; when they detect the athlete again, the clock stops or records the lap in a custom log of pace records. A custom-wired breadboard connects every sensor, button, and display into one responsive system. The bright LCD shows the active time and recorded lap, while dedicated button controls make saving a result or resetting the clock effortless. Previous results remain stored and ready for review until the device is powered down. The custom 3D printed shell houses all the components into a durable protective case so the device is ready for any environment. Turn it on. Step to the line. Achieve your best.
Every hundredth earned. Every result trusted.
This stopwatch began with one question: what if timing could move as fast as the athlete? By replacing human reaction with automatic dual-sensor detection, it makes every run precise, consistent, and effortless to measure. From the first stride to the finish, the technology stays out of the way and lets performance take center stage. Built by a coach, tested through real movement, and designed for athletes who refuse to leave progress to guesswork. Turn it on. Step to the line. Let your performance speak for itself.
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