I found a project called Laptracker that keeps track of RC cars during a race. This uses IR leds and receivers along with an Arduino and ESP-01 This works great by the way. I would like to use this project for dirt go kart racing but do not want to use the IR technology. Basically I need to trigger the ESP to transmit its chip ID by wifi to a TCP port. I don’t know if magnets would be strong enough to trigger a reed switch. This reed switch would be mounted above the ground approximately 6-8 inches away from the magnet. Another idea I had is to bury a loop wire in the track and trigger the ESP with a frequency if possible. I’m thinking of using an amplifier aka induction loop to transmit this frequency. I would be able to pick this signal up 3-5’ easily above ground. I would need a rc band pass filter for this frequency along with a pickup of some sort. I don’t know if a T-coil would work like they use in hearing aids. This coil may pickup interference that the go kart engine may be producing. Maybe someone would have a better idea. They sell go kart transponders and software but it’s very expensive. This is just for backyard fun.
why not use RFID tags?
something like this might just be ok to read the tags from a 'distance' though tbh u may need a couple layed out in a line...
Another option is to have a metal strip as your 'lap' line and have a metal detector on your go-cart. whenever the metal strip is detect, it then sends the mac-addr (Chip id) of the esp-01 to the server.
hope that helps...
RFID works only within a distance of 5 cm. That's pretty narrow.
Dirt go karts humans are sitting in or RC dirt gokarts?
How about a ligh-curtain? Not a single light barrier but a dozen of them each 2 cm higher as the other?
don't know how much money you want to spend. With small 0,5 miiliwatt laser-modules it should work reliable over a distance of some meters. You should'nt use 1mW or 5mW lasers because their intensity can cause severe damage to the eyes. The lens in your eye concentrates the laserlight to 0,01mm and then the intensity of more than 0,5mW is high enough to burn out the light-sensititve cells in your eyes.
Don't know how your race-track looks like so it is difficult to make suggestions. If you could post a picture of your racing-track this will be inspiring for ideas.
best regards Stefan