40 Yard dash laser timer

Hello, Id like to make a timer that is accurate but relatively cheap(~200 or less). Is this possible for an accurate one at that price. Id like it to time every 10 yards so it would need five laser distance finders (start, 10, 20, 30 and 40(aka end)). Where if you pass through start it starts a timer and when you pass through the second stops timer etc till you are done. then at the end adds all the times together and shows up on a lcd (displaying total time and all increments)

How many runners? Or is it just the leader? If so you could get the stage time from various leaders thorough the race.

Just one its a 40 yard sprint.

Does it matter if a flailing arm breaks the beam sometimes and a body at other times?

Measuring the time between beam-breaks is the easy bit.

...R

Note that breaking a beam at the start is not the same as the time of the starting gun.

The interesting thing about electronic timers is that - given a proper crystal on the MCU - they are to all intents and purposes in sport, always dead accurate.

In measuring time, that is. Judging the actual start and finish events may take somewhat more consideration of just how you define them.

When i said accurate its just for a reference. This is not for an event just for athletes to know where they need to work for their 40. No it does not matter if an arm breaks it. And the way we do it is when the athlete starts the timer starts. So when he breaks the beam the timer starts and etc.

What about filming the race at a high frame rate and playing back the film to figure out the timing. Maybe you could film a watch in the corner of the screen. I think most medium range modern cameras can work at high frame rates. My Fuji HS50 can record at 240 frames per second.

...R

JohnLincoln: You might want the start signal to be taken from some form of switch on the starting block, rather than a beam being broken. Otherwise the athlete will already have to have traveled some distance before the first even it signaled.

OK well we could just manually start it. then after that i want it all automatic(human reflex is nowhere near the speed of a computer).