A transmitter sends an I/R beam up to 75 feet to a receiver (on separate pc boards); break the beam and a relay is tripped. Use the relay to control a bell or light or other device ; even a video recorder and camera. Operation requires 9 to 12 VDC; a wall adaptor is fine and you may want two units (provision is made to power both boards with one supply via a two conductor wire). Use to watch a hallway or drive way; across the doors to a three or four car garage etc. and we know of a photographer taking wildlife photos this way. The uses for alarms; photography; door minding and so on are numerous. You could make weatherproof hoods to use out-of-doors but be sure to protect from moisture.
