If you've been assuming that on-site and compact video security systems are a relatively modern thing...think again. This is a GE advertisement for a residential video monitoring system (tube-powered at that!) which allowed the resident to hear and *see* who was at the door via a wall-mounted television screen.

Not all those electronic toys and gadgets that are now out there are "new". Many are improvements upon prior concepts (at least making it to the drawing board) ...some going back 50 or more years ago!