Abstract: An intrusion detection system is specifically designed to avoid actual confrontation within a protected premises between a returning occupant and an intruder. The system forewarns a returning owner or occupant, before entering the premises, that an intrusion has occurred by providing a signal visible from the outside of the premises. In this manner, the owner is alerted to the possibility that an intruder may still be present within the premises, and confrontation is avoided. The system includes a test mode operable from outside the protected premises to determine if the system has been tampered with by an intruder. If no intrusion signal is observed by the returning owner, he must still test the system to ascertain if the absence of the intrusion signal is a result of no intrusion, or if it is the result of an intruder having tampered with the system, by for example, removing its power supply.

Abstract: The present invention provides an improvement by adaptation of a rising stem fuel oil gauge for indicating, at a remote location, the quantity of fuel in oil storage tanks commonly used in homes and businesses. The improvement includes a magnet carried on a horizontally positioned level indicating disc, which is attached to the upper end of a vertically rising stem and enclosed within a transparent tube. Markings on the tube correspond to the quantity of fuel oil within the storage tank and the alignment of the indicating disc with a specific marking indicates the fuel oil quantity at any given time. A magnetically actuated reed switch is mounted to the exterior of the tube at a predetermined position, and a power supply and remote alarm are coupled to the switch. When the level of the indicating disc is near the position at which the switch is mounted, the magnet carried on the disc actuates the switch which in turn actuates the remote alarm.