Fun fun, finding wierd stuff stashed away. Sorry about the bad picture, I tried to throw something up before going to work. The ground wire (alligator clip) is connected to a spool of wire on a very thin wire. yellow is to a "capacitor" type module, red is to the top framing of the unit which does overlay the ground side with a gap there (instant motion detector thoughts come to mind). Im guessing its a motion detector type of unit by my novice guess. Just a little curious if this really indeed was once wired to the interior lights. Blah, too much work lately, must sleep and return to work. Ill read your thoughts more thouroughly after work tonight geezer, thanks.

You could be right on both counts. I have designed and built some custom units. Everything from motion detection, RF signaling devices to a current silent system that will automatically call a list of predetermined cell or phone numbers. The one you have there, seems to be someone's homemade (adapted) version of whatever they had in mind. Normally, the unit you have found, would not have an aligator clip on it, but instead, would have been routed through a simple hidden toggle switch and ultimately connected to a door (or more than 1 door) switch. Anyone opening the door before disarming the ground signal with the toggle switch would set off the alarm. The "capacitor" type module you found going to the yellow wire...is it 2 legged? Of course, I haven't seen or tested this thing so don't put too much stock in what I've said.