LED light switch

[Dave Edwards]

Hey folks....I was hoping someone on the list could suggest a simple circuit arrangement for me. 
I have a simple application. 

On a simple track, I want to time my kid's pinewood derby car as I make adjustments in building it. 

I have an old Heathkit stop watch that has external inputs for start and stop. 

A closure will start the watch, and a differant closure will stop it. 

So, the question is....How can I make a small pinewood derby car on a 10 foot or so track close a contact at the start, and close another contact at the finish?

I first thought of hanging paperclips to mechanically make contact when the car touches them, but ....too unreliable. 

There must be an LED and photosensor, connected to a chip that senses the light beam being broken and latching a set of contacts??  Sure sounds like a Radio Shack thing to me. 

Any ideas??

Sorry for the off-topic...accept that it uses an old Heath stopwatch!!!

....Dave

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