Our automatic garage door opener has a circuit that is composed of two LED's, one at each end of the door, and while it's closing if you break the beam from one LED to the other, it will stop the door from moving any further.
What is the formal name for this kind of a circuit, and where can I learn how to build one?
Thanks
What is the formal name for this kind of a circuit, and where can I learn how to build one?
Thanks