Main Question or Discussion Point
I wanted to build my own doogie door that would be able to recognize when my dog was near by and could unlock the door, and then lock it again when the dog has successfully gone through. I have a problem with raccoons in the neighborhood, and I don't want sneaking into a traditional door. A friend of mine suggested using an "induction loop sensor, like they use for traffic lights", but I have no idea how to build or make such a thing. Any thoughts or general directions would be greatly appreciated!