Abstract: An obstruction sensor for an electro-mechanically operated garage door which utilizes a bracket for supporting one end of the trolley that carries the door and which is driven by the motor either through a chain or worm and wherein an obstruction encountered by the door will cause the rail to move relative to a fixed bracket thus causing a reversing switch to be energized due to relative motion between the fixed bracket and the rail which will cause the motor driving circuit to reverse the motor thus causing the door to move away from the obstruction.

Abstract: A solar receiver in which a rod of high thermal conductivity is mounted in an evacuated envelope so as to receive thermal energy and which is coated with a selective absorbing surface so as to minimize radiation has a heat transfer end which is surrounded by a suitable material such as pyroceram or porcelain or other suitable material which extends into a container from which the heat produced by the solar energy is removed. The glass envelope surrounding the rod is attached by welding to the pyroceram cylinder and the heat transfer cavity is connected with an O-ring to the pyroceram cylinder so as to provide a liquid seal.

Abstract: A hinged screw section for a worm drive garage door operator which allows the worm shaft to be assembled at the factory and folded back upon itself so that it can be shipped in a smaller and shorter package. Two different joints have been developed, one of a "I" type in which the connecting link between the two sections of worm shaft is merely a flat metal section with a hole in each end which fits into a slot in the ends of the two worm shaft sections and the assembly is pinned together with two rivets or bolts and the spacing between the two threaded shafts is such that a rack driven carrier will mate with threads of each portion. A second configuration utilizes an "H" joint and the link contains slots and flat tangs are formed on the ends of the two threaded shafts and joined with rivets to the link.

Abstract: A compact container system which utilizes minimal storage space is provided for packaging and shipment of an electric garage door opener. Among the many components of the container system is a corrugated cardboard shipping carton for snugly holding the motor unit or power opener head of the garage door opener. One of the sidewalls of the shipping carton includes an access flap for the optional insertion of an auxiliary transmitter.

Abstract: A loudspeaker system which has a frequency response at any angle located about the speaker system which will be uniform such that the output sound pressure at any frequency from the speaker system will be as great or greater than the sound pressure from any other direction which comprises a reflected path from the speaker system. The speaker system includes a radial horn which radiates a spherical sector rotated 360.degree. through a horizontal plane is provided. One or two speakers are mounted so that they produce a pulsating cylindrical wave which feeds into the radiator and an inverted conical member is mounted in the transition portion between the pulsating cylinder and the output horn portion. This output is blended with similar wavefronts produced by a low fequency loudspeaker which is acoustically associated with a vented box. The vent is on the periphery of the box adjacent the low frequency loudspeaker and is narrower than the thickness of the walls of the box.

Abstract: An extension and retraction mechanism for a three section extensible boom is disclosed utilizing an internally disposed hydraulic cylinder connected between a stationary boom section and an intermediate boom section with a cable connection located entirely interior of the boom having opposite ends anchored to opposite ends of the stationary section with the cable routed around sheaves on the moving end of the hydraulic cylinder and a base end of the intermediate boom section with a cable attachment to the base end of the inner boom section, the inner boom section being the most extensible boom section.

Abstract: An overload circuit for a loudspeaker system which indicates the overload and also automatically reduces the load on the speaker system to prevent damage in which a rectifier followed by a smoothing circuit is connected in parallel with the speaker and supplies an output to a magnetic coil for energizing a magnetic switch on overload so as to place a load dropping means in series with the speaker during overload. The load dropping means might be a lamp which visually indicates the overload condition.

Abstract: An accessory for a garage door opener which includes a circuit which is energized when the garage door operator is actuated and which can be used to energize a power circuit as, for example, a lamp so as to provide illumination upon energization of the garage door operator. The lamp automatically turns off after a pre-set time and can also be manually controlled by an on-off switch.

Abstract: An improved digital radio control including a transmitter and receiver utilizing codes in which a plurality of switches at the transmitter and receiver establish a binary serially transmitted code for energizing only a particular receiver which has its switches set to the same binary code and wherein the different conditions of the binary code depend upon the pulse length such that unique codes can be selected for particular transmitters and receivers so that interference with other systems in the vicinity will not occur.

Abstract: Method and apparatus for improving the behind-the-targets effects of shaped charge munitions which provides a secondary target defeating mechanism which follows through the opening formed by the high velocity jet which perforates the target. The shaped charge liner may be axially symmetrical in the form of a cone or section of a sphere and behind the apex is mounted the follow through secondary target defeating mechanism which is surrounded by the explosive charge. When the charge is ignited the resulting detonation wave collapses the liner into a high velocity jet or slug that perforates the target after which the follow-through agent is driven through the perforation. The follow-through agent may be pyrophoric or ignitable and such agents will increase the temperature and pressure particularly if the target is a closed target. Other materials may be used and introduced into the target through the perforation.

Abstract: An extension ladder including a base section and a fly section, each having a pair of side rails and including, mounted at the ends of each of the side rails, a guide unit interconnecting the adjacently sliding side rails of the fly and base section, said guide unit also including an integrally formed cut protector portion and slide pad.

Abstract: A digital radio control system comprising a transmitter and receiver wherein a plurality of two position switches may be set in a transmitter to pick a particular code which will be serially transmitted by the transmitter and in which a plurality of switches in a receiver may be set to a particular code such that if the same code is selected in the receiver as is set in the transmitter the receiver will be energized upon recognition of the code. Such transmitters and receivers are adaptable to many applications, as for example, garage door actuators; and due to the large number of possible code combinations, interference between other control units within radio frequency range will not occur.