Need Help

Can anyone here help me figure this out. Need to setup two IR beams that when broken will trigger a relay of some sort.

Here is what I'm doing, trying to build a timer for a local mud truck rally. the track is setup like a drag strip and is 100 foot long. I found a setup where they used a hand held stop watch with a switch wired to the start and stop button of the stop watch. Pretty simple, but I need the switch to be the IR beams spanning the start and finish line with a 2 second delay so it wont turn the stop watch off when the rear tires brake the beam.

Thanks Steve............

Thanks so much for all the help, you guys are the best..... Not!

R U still there? I think I would use the ir detector used in tv's along with a higher power ir led. Can you wire up some circuits?

I sure can, just need to know what components I need and a schematic for dummies. I've been looking online and I can't find anything simple enough for me to understand. Not sure what kind of IR sensor, or how I can make it trigger a relay or the start stop button of an electronic stopwatch. I figured one beam at each end of the track to trigger the stopwatch on and off switch. Might have to build in a 2 second delay on the sensor so the rear tires don't stop the stopwatch.

Thanks Steve........

Not sure the distance needed but may be able to use the ir sensors from a garage door, the ones at the bottom to detect an object in the path of the door.

Neal said:

Not sure the distance needed but may be able to use the ir sensors from a garage door, the ones at the bottom to detect an object in the path of the door.

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Yes you can from what I have read, they are available up to a 30 foot range but how would you wire them to the stopwatch? and what would you use for a delay?

Hi 393clevor,

I guess you're overcomplicating things.

Use a non-retriggerable circuit to activate your timer circuit (or clock). (Google for non-retriggerable one-shot)

It doesn't matter how long the beam is broken, just the initial breakage is the valid one.

The stopwatch should have a button (electrically opening or closing) which you can jump using a miniature relay.

Welcome for mud-racing in the rice fields of Thailand. Farmers certainly will appreciate free plowing.

Regards

Boncuk

Use the garage door sensors for start and end. Google 555 one shot for the start timer delay. It will not trigger a second time for the rear wheels. For the end time the photo transistor from the garage door sensor should trigger the stop.