Abstract: A vibration sensitive trip switch for a vehicle alarm system or the like comprising a pair of juxtaposed generally coextensive cantilevered flat clock springs spaced one above the other. Each cantilevered spring is secured to a bracket. The upper spring extends horizontally over the lower spring with the latter canted toward the free end of the overlying spring, terminating spaced a predetermined distance below same. The springs have facing contacts at their overlying free ends, with a fine gap defined therebetween. The springs are movable in an uninhibited manner at their free ends and are weighted unequally thereat, the underlying spring carrying a greater weight than the overlying spring. A shock pad is located immediately below the free end of the underlying spring. The overlying spring is sensitive to shock caused by sharp jars resulting from impact against the windows or tires as would occur during attempted theft or vandalism.

Abstract: A siren for an alarm adapted to be driven by a fractional horsepower motor and provided with a cup shaped rotor cooperating with a stator provided with perforations in the cylindrical flange thereof, and a drawn, cup-shaped screen or grille seated over the inlet to said stator and having a cylindrical flange extending over the perforations of the stator but spaced outwardly therefrom, the base of the screen being engaged on the stator rim. The intake air flow of the siren is restricted by the perforations of the screen which increases the velocity of the intake air, thereby increasing the efficiency of the siren which enables reduction of the current usage requirements. The harmonics of the output sound are increased by the perforated cylindrical flange of the screen thereby increasing the volume and pitch of the emitted sound.

Abstract: An electric key-operated switch adapted to be mounted on the exterior of a vehicle or structure to arm or disarm an alarm system. A key is to be rotated in a cylinder between two positions, each of which controls a separate circuit that is normally open when the contact rotor carried by the cylinder is not engaged with contacts connected to the respective circuit. The invention provides more positive electrical engagement and a novel structure for economically adjusting the limits of positions of the contact rotor so that the key may readily be inserted and removed.

Abstract: A siren for an alarm adapted to be driven by a fractional horsepower motor comprising a cup-shaped rotor cooperating with a stator having rectangular perforations in a cylindrical flange, the cup-shaped rotor and the stator being both formed as stampings, the rotor having an integral base plate staked to a hub, the base plate having a plurality of shear-formed upstanding vanes of identical irregular polygonal configuration circumferentially arranged around the center of the base plate, the cylindrical wall of the rotor having rectangular perforations equal in number to the number of vanes and each vane having a perforation adjacent thereto at the identical respective location.