Hello, first of all I have very little experience with circuits and ir stuff so please excuse me if I am not using the correct terminology. What I would like to build for my kids is a simple ir beam break finish line for hot wheels cars, it needs to be 2 lanes that simply turns on an led light for the lane that finishes first...I would like the led to stay lit for 5 to 10 seconds then reset for the next race. It doesn't seem like it would be very difficult but again I have little to no experience with this type of stuff...just a dad that wants to build something for his kids. I have attached the ir beam break sensor I was wanting to use. The space between the top and bottom of each lane will only he 5 inches or so. Any help is greatly appreciated and thanks in advance.

https://www.adafruit.com/product/2167

 

Welcome to AAC!

You won't be able to tell which car broke the beam first unless you use two sets of them.

If you can attach a small magnet to the cars, you could use a hall effect sensor in each lane. If that won't work, you might be able to use a micro switch in each lane

 

Hello, thanks for the quick reply. I thought it would be possible to have two sets of ir breaks one set for each lane...then connected to something...(dont know what) that would tell which lane was first? There was someone who used to sell a version but has since stopped making them hence the diy attempt.

 

You could use two 555 timers and have the first one triggered disable the other one.

 

then connected to something...(dont know what) that would tell which lane was first?

Here's a circuit that should do it:

Initially both timer outputs will be low. The inverters on each output will enable both timers. The first lane break trigger will turn on the corresponding LED and disable the other timer. After about 10 seconds, the timers will be ready for the next race.

I didn't look at the details for the sensors you want to use, but the timers trigger on a negative going edge from the sensor.

EDIT: One thing to consider is that IR sensors will be affected by flourescent lights, so you'll probably want the emitter pointing up and the detector pointing down.

 

Hello, first of all I have very little experience with circuits and ir stuff so please excuse me if I am not using the correct terminology. What I would like to build for my kids is a simple ir beam break finish line for hot wheels cars, it needs to be 2 lanes that simply turns on an led light for the lane that finishes first...I would like the led to stay lit for 5 to 10 seconds then reset for the next race. It doesn't seem like it would be very difficult but again I have little to no experience with this type of stuff...just a dad that wants to build something for his kids. I have attached the ir beam break sensor I was wanting to use. The space between the top and bottom of each lane will only he 5 inches or so. Any help is greatly appreciated and thanks in advance.

https://www.adafruit.com/product/2167

https://www.dfgtec.com/pdt

Maybe this will help.

kv


dl324 has a better idea.

 

Yes, this is the info i was looking for. Im gonna order the IRs and 555 and give it a go. Ill post updates as i progress. If yall think of any additional info or advice, please let me know. Thank you!

 

Im gonna order the IRs and 555 and give it a go.

Note that I used a 556 timer. That saves you two connections.

Put the IC's in sockets. That'll save you some grief if you need to replace them.

 

Yes, 556. Thanks for pointing that out. This will be a learning experience!

 

If you want to get really fancy you can go this route.
A design for a 3-track Pinewood Derby finish lights is discussed here.
It discusses a design for three tracks and LED 7-segment displays that show 1st, 2nd and 3rd place.
If nothing else, you might learn something from just reading the full thread.

 

Thank you MrChips. It might be way over my head, but im gonna take a look at it.

 

This will be a learning experience!

You'll also need to tie the inputs of the 4 unused inverters to ground and add supply decoupling.