Abstract: A clamp for securing an adjustable bar hanger to a molded thermosetting plastic electrical wiring box. The clamp includes a generally U-shaped portion having a deformable tab directed into the region defined by the U-shaped portion, a first pair of spaced-apart L-shaped positioning tabs at one side of the U-shaped portion, and a flange extending outwardly from the other side of the U-shaped portion. A bar hanger is positioned within the U-shaped portion of the clamp, and the wiring box is oriented with respect to the clamp and bar hanger assembly so that the pair of L-shaped positioning tabs can be readily inserted within a corresponding pair of spaced-apart slots formed in a rear wall of the wiring box. The wiring box is then pivoted with respect to the clamp so that the bar hanger is captured between the clamp and the rear wall of the wiring box with the clamp being spaced a slight distance from the rear wall of the wiring box.

Abstract: Receiving apparatus for processing differential quadrature phase shift keyed (DQPSK) signals. Received 70 MHz IF signals are mixed with a 70 MHz reference frequency to provide quadrature components of each received signal. The resultant of the quadrature components of each signal is converted to a digital representation. The digital representations are sampled at sixteen times the baud rate. Samples are subtracted by two's complement addition and the difference produced by samples from two successive received signals is read out as the data encoded in the signal. The resultant of each two's complement addition is monitored to determine if there is no difference indicating that the samples are from the same received signal or if there is a difference indicating that the samples are from different received signals.

Abstract: Electrical contact material of silver or mixtures of silver and a thermally decomposable compound of silver having an additive of an alkali metal, for example lithium, added in the form of a salt prior to sintering to increase the as-sintered density of the resulting material and to aid in the prevention of undesirable surface blisters. The silver material may be fabricated as a backing layer on a primary contact material of silver-cadmium oxide.

Abstract: A clamp for securing an adjustable bar hanger to a molded thermosetting plastic electrical wiring box. The clamp includes a generally U-shaped portion having a deformable tab directed into the region defined by the U-shaped portion and a pair of side flanges integral with and on opposite sides of the U-shaped portion. A bar hanger is positioned within the U-shaped portion of the clamp and the wiring box is oriented with respect to the clamp and bar hanger assembly so that the bar hanger is captured between the clamp and a rear wall of the wiring box and the clamp is spaced a slight distance from the rear wall of the wiring box. Screws are then inserted through openings provided in the rear wall of the wiring box and threaded into corresponding threaded openings provided in the flanges of the clamp.

Abstract: A magnetic trip assembly for use in a device such as an electric circuit breaker. The magnetic trip assembly includes a magnet and an armature arranged with respect to the magnet to coact with a pole face of the magnetic member which is in a plane normal to the magnetic plane of the magnetic member. An electrical load conductor is coupled to the magnetic member and establishes together with the magnetic member a magnetic field for closure of the armature in response to specified, excessive values (short circuit or overload values) of current passing through the load conductor. When the armature is operated to its closed position, a first portion of an actuating and latch member abutting against the armature is caused to move, in turn causing a captive, generally-cylindrical portion of the actuating and latch member to rotate.

Abstract: Low level amplitude modulated radio transmitting apparatus employing a DC control loop from the output amplifier to the audio modulating stage for maintaining the carrier output level constant. The audio signal to be transmitted is superimposed on the DC control signal and the resulting signal is applied to an operational amplifier that controls a current driver supplying operating potential to the modulating stage. A DC limiter at the input to the operational amplifier limits the DC control signal to the operational amplifier thus preventing continuous overdriving of the RF elements in the event of a disruption in the DC control loop. An audio by-pass permits the audio signal to by-pass the DC limiter and be summed with the limited DC control signal at the input to the operational amplifier.

Abstract: Circuit breaker having a trip arm which is released during tripping of the breaker under overcurrent conditions. One end of a contact opening arm is pivotally mounted on the trip arm. When the trip arm is released, the trip arm also contacts the other end of the contact opening arm forcing it against the contact carrier which supports the movable contact thereby opening the contacts.

Abstract: Symmetrical push-pull power amplifier employing a pair of complementary output transistors having their collectors connected to an output terminal. The output transistors are each driven by an associated input transistor of the opposite conductivity type. Feedback diodes are coupled between the collector of each output transistor and the input of the input transistor associated with the other output transistor. A feedback diode is forward biased while the output transistor to which it is coupled is conducting, thus biasing to nonconduction the input transistor to which it is coupled. Therefore, when the polarity of the input signal to the input transistors changes, the output transistor that is off is not turned on until the output transistor that is on has dissipated the charge stored therein and is not conducting.

Abstract: An electrical wiring box having a pair of mounting elements attached thereto for use in mounting the wiring box within an opening in a supporting structure such as wallboard or panelling. The wiring box includes first and second mounting portions each having a pair of spaced slots therein. Each of the mounting elements includes a pair of locking tabs and a flat portion having openings therein connected with the locking tabs. The locking tabs are adapted to be inserted into the pair of slots in the corresponding one of the mounting portions for attaching the mounting element to the wiring box. The flat portion is adapted to receive fasteners in the openings therein for mounting the wiring box to a supporting structure.

Abstract: Apparatus for producing drive signals on any of several lines in response to input signals. Each of the lines has a drive circuit connected thereto. Resistances connected to the outputs of the drive circuits are connected together at a common juncture which acts as a summing point having a voltage proportional to the number of lines having drive signals thereon. First and second comparators are coupled to the common juncture and to threshold setting arrangements. The first comparator produces a signal if one or more of the lines has a drive signal and the second comparator produces a signal if two or more of the lines have signals. The outputs of the comparators are combined in alogic arrangement to produce an error signal if none of the lines has a signal or if two or more of the lines have signals. The threshold setting arrangements include a threshold setting drive circuit identical to the other drive circuits.

Abstract: A data transmission and display system including an input data source for transmitting data over a coaxial cable to be processed for use by a remotely-located CRT video display monitor and associated input/output devices and for receiving data over the coaxial cable initiated by the input/output devices. The data transmitted to the CRT video display monitor and to the input/output devices and the data received from the input/output devices takes the form of a plurality of successive data frames each comprising a plurality of successive data intervals. In the first interval of a frame, data is transmitted by the input data source over the coaxial cable in a forward direction to be used by one or more of the input/output devices for performing certain operations specified by the data. In the second interval of the frame, data which may be initiated by one of the input/output devices is transmitted over the coaxial cable in the reverse direction to the input data source for utilization thereby.

Abstract: An electrical wiring box having a pair of mounting elements associated therewith for permitting the quick and easy mounting of an electrical device within the wiring box. The wiring box includes first and second mounting portions each having a central opening and a pair of slots on opposite sides of the central opening. Each of the mounting elements includes a screw-receiving section adapted to be inserted into the central opening of a corresponding one of the mounting portions of the wiring box, and a pair of locking tabs adapted to be inserted into the pair of slots in the corresponding one of the mounting portions for attaching the mounting element to the wiring box and for properly positioning the screw-receiving section within its corresponding central opening. Each of the screw-receiving sections includes three thread-engaging members arranged to define a screw-receiving region therebetween and each having a deflectible thread-engaging tip directed into the screw-receiving region.

Abstract: Series voltage regulator including pass transistors connected between an input terminal and an output terminal. The voltage at the output terminal is stabilized by a feedback arrangement of a reference amplifier and coupling transistors connected between the output terminal and the bases of the pass transistors to control conduction through the pass transistors. A normally non-conducting protective transistor is connected between the bases of the pass transistors and ground. In the event the regulator is exposed to radiation, all the transistors become highly conductive. However, when the protective transistor becomes highly conductive, it biases the pass transistor to cutoff thus preventing the voltage at the output terminal from rising out of control.

Abstract: A back-lighted display arrangement including a soft, compressible opaque light baffle sandwiched between a lamp assembly and a display panel. The light baffle has a grid-like configuration defining a plurality of compartments each of which is arranged to receive a different one of a plurality of lamps supported by the lamp assembly and to direct light emitted by the lamp onto a different one of a plurality of display areas of the display panel. The light baffle establishes a positive light-tight seal between the baffle and the lamp assembly and display panel for preventing light in one compartment from escaping into an adjacent compartment.

Abstract: A low-profile lighting fixture particularly suitable for low and medium height mounting installations. The lighting fixture includes a housing assembly comprising a base member and first and second end sections at opposite ends of the base member. The first and second end sections respectively contain a power supply ballast transformer and capacitor for the fixture. An upstanding bracket supporting a horizontally-oriented lamp-receiving socket is attached to the base member intermediate to the first and second end sections, and a generally-rectangular reflector having an opening therein is mounted to the base member in line with and intermediate to the first and second end sections with the lamp-receiving socket extending horizontally into the interior of the reflector via the opening in the reflector.

Abstract: Scanning apparatus for monitoring 88 telephone subscriber lines to detect the on hook or off hook condition of the lines and to detect and count dial pulses. A multiplexing arrangement produces a sample of the incoming signal on each subscriber line in a recurring sequence. The apparatus includes a memory for storing an indication for each subscriber line as either on hook or off hook, a memory for storing the most recent sample for each subscriber line, a memory in association with a counter for storing dial pulse count information for each subscriber line, and a memory in association with a timer for storing timing information for each subscriber line. The multiplexing arrangement and the memories are coupled to a decision section of an arrangement of logic decision blocks which analyze each sample together with the stored data associated with the same subscriber line. Depending upon the particular combination of information presented to the decision section one of several end-state flip-flops is set.

Abstract: An electrical bussing and jumper assembly for use with electrical switching devices such as circuit breakers in a three-phase distribution system. The bussing and jumper assembly comprises a plurality (three) of relatively thin, wide, bus plates stacked together in a compact sandwich-like array. Each of the plates has a plurality of jumper portions extending transversely through openings or cutouts provided in the bus plates superimposed thereover. The bus plates are insulated from each other by means of insulative coatings (e.g., of polyvinyl chloride) formed on the plates and also by means of sheets of insulative material (e.g., of polyethylene terephthalate) disposed between the coated bus plates and having openings therein aligned with the openings in the bus plates. Switching devices for use in a current distribution system are attached to the jumper portions of the bus plates, using threaded openings provided in the jumper portions.

Abstract: A two-part electrical surge arrester for protecting electrical equipment within a shielded enclosure from electromagnetic pulses and lighting on incoming lines. One part mounted on the exterior of the enclosure wall includes a chamber having fifty-five spark gaps employing a common ground plane. The second part mounted on the interior of the enclosure wall contains fifty-five current limiting resistors and fifty-five low pass filters. When both parts are mounted on opposite sides of the enclosure wall contacts from each engage through an opening in the wall to provide fifty-five protective paths between incoming lines and equipment within the enclosure.

Abstract: Digital signal generator for producing digital signalling codes employed in a digital telephone communication system including several tone generators for providing presynthesized digital tone signals which are convertible to audible tones. Permutable digital codewords are produced by a codeword generator. Some of the tone signals and codewords are combined by FSK and switching circuitry. Tone signals, codeword signals, and combination signals are stored in storage registers and read out by a multiplexer to provide a continuous TDM bit stream of 60 channels of digital signalling codes.

Abstract: A lighting fixture adapted to be mounted to a support structure and wired with a minimum expenditure of time and labor. The lighting fixture includes an enclosure member defining a space for containing a power supply for the fixture, a support and wiring tray to which the power supply is mounted, a pair of hinge members jointly attached with the enclosure member and the support and wiring tray, and a cover and enclosure member removably attached to the hinge members by means of associated pairs of threaded bolts. In a typical installation procedure for the lighting fixture, the fixture is first mounted to a support structure by means of an attachment member secured to the cover and enclosure member, and one of the pairs of threaded bolts is removed from its associated hinge member to allow the remaining portion of the fixture to swing away and to hang suspended from the other pair of threaded bolts. As a result, the installer of the fixture has both hands free to perform the required wiring connections.