Abstract: An apparatus for switching an alarm-signalling device connectable to a protective circuit so as to signal an alarm when a door or the like is displaced from its closed position in a jamb or the like by an intruder, in which the switching apparatus is mounted in the door and jamb or the like. The switching apparatus includes a switch connectable to the protective circuit, mounted in a housing installable so as to be recessed in the jamb, and a metal plate installable so as to be recessed in the side of the door and disposed opposite the switch when the door is closed in the jamb.

Abstract: An apparatus for switching an alarm-signalling device which is connectable to a protective circuit so as to signal an alarm when a door or the like is displaced from its closed position in a jamb or the like by an intruder, in which the switching apparatus is mounted in the door and jamb or the like. The switching apparatus includes a switch which is connectable to the protective circuit, which is mounted in a housing which is installable so as to be recessed in the jamb, and a magnet which is magnetized such that opposite faces thereof define poles of opposite polarity, which is mounted in a housing which is installable so as to be recessed in the side of the door and disposed opposite the switch when the door is closed in the jamb.