I want to create a brake light on a motorcycle helmet which will turn on when the brakes are applied. I need a very small transmitter and receiver pair. The range obviously does not have to be far, six feet would probably be plenty. Also, a way to make these not interfere if multiple riders are in close proximity would be nice. Any suggestions for hardware?
I did exactly that some years ago under a contract to someone with aspirations to make such a product.
After I delivered it, he found that one can purchase these things.
I used a 433MHz transmitter/receiver pair. The hard part was the battery/packaging.