Model Car LED Finish

[koliver_va]

I need help with a circuit to show the winner of a wooden model car race. This is something that they do in Scouts. They race four cars on a set track and all cars will pass by a sensor in there track. This can be feed into a computer or a stand alone display displaying how is 1,2,3rd of 4th. Any ideas will be helpful.
Thanks

 

[hizzo3]

you could try a sensor system using infared. that is how our conveyor works at work. the emiter is on bottom, and so is the collector. to make things simpler for u as far as optics go, put the collector opposite of the emmiter in the track. Think of those door chime things in small shops when u walk in they make the ding sound. You then can have it set off a trigger circut.

just fyi. when i was in scouts, ours used a pressure sensor at the end of the track. had some foam on it to protect the cars. first to hit it won and went down the list.

 

[koliver_va]

The trigger part I have, it is that we wanted to have a display that says 1, 2, 3 and 4 over the track. If track 1 is second then on a LED display the number 2 will be there. I was looking at optic's and diodes in the track to be the trigger. It has been YEARS I was in school for this. Radio Shack just introduced the Model One Computer.
Thanks, for the help.