Abstract: A unitary molded socket provides mounting for non-temperature compensated crystals, a resistor heating element for each crystal, and a thermistor. Each heating element is positioned adjacent a crystal housing for preventing the housing temperature from going below a given temperature. The thermistor is thermally coupled to one of the resistors for sensing its temperature and electrically coupled to control circuitry for providing the appropriate heating current to the resistor heating elements. A spring clip biases each crystal against its resistor, clamps it into the socket and is pivotable for replacement of components.

Abstract: In a two-way communications system involving portable-mobile-base station transmission, a priortization method prevents interference caused by more than one mobile repeater at a single location relaying simultaneously, or by a lowband transmission skipping in from another location. When a repeater enters the system at a location, it monitors the base and portable channels, and if there is transmission activity on either channel it goes to a non-priority state. If there is no activity, a silent carrier burst is momentarily transmitted on the base channel, then the repeater goes to a non-priority state. Unless a repeater at the scene is in the priority state, each other mobile unit, upon detecting the burst, begins to repeat it out on the portable channel. When interrupted by its interrupt clock, the repeater listens for a short interval on the portable channel and if any transmission is heard, remains inhibited or in "receive" mode.

Abstract: An improved socket assembly is disclosed which is especially suited for use with printed circuitry. The socket is mounted on an associated printed circuit board and is adapted to receive and retain guide pins of electronic circuit modules or the like. The socket assembly further includes a non-metallic insert, such as Teflon or equivalent material, which is introduced into the socket before soldering. The insert is unaffected by the molten solder or flux and prevents entry of contaminating material into the interior of the socket during the soldering process. The insert is removable by the insertion of a module guide pin during assembly of the component mounting board.

Abstract: The microphone of an electronic device is mounted within the housing of the device, and may be a microphone cartridge having a sound opening exposed to a sound chamber within the housing. The device may be a portable radio transmitter and receiver wherein the housing has a wall with a grille screen for providing sound transmission between the inside and the outside of the housing. A cavity is provided inside the housing adjacent the screen for receiving sound to be applied to the microphone. A sound passage connects the cavity to the sound chamber which acts as a reinforcing chamber to apply sound to the microphone. In a radio transmitter and receiver, a loudspeaker may be positioned to project sound through the grille screen, and the cavity between the loudspeaker cone or diaphragm and the screen forms the cavity for collecting the sound.

Abstract: A support system, for mounting enclosures on hollow poles of the type located on a highway right-of-way and having a range of diameters and wall thicknesses, has a bracket plate which is fastened to the back of the enclosure with mounting subassemblies inserted through holes in the bracket and in the pole wall. Each subassembly comprises a slotted expandable tube, a locking bolt and a special nut. Interaction of the nut and bolt cause expansion of the tubular member, locking the bracket to the wall of the pole. Also in the bracket and aligned with each subassembly, are two angled, threaded apertures which retain stabilizing screws. Subsequent to the locking action, the screws are advanced into forceful contact with the exterior of the pole wall. An enclosure back portion is then mounted on the bracket by hexagonal head bolts or the like, the heads of the bolts being seated in hexagonal depressions in the rear of the brackets for inaccessability from the outside of the cabinet.

Abstract: An electronic apparatus as for use in a vehicle is adjustably mounted on a rigid support member by means of rigid inserts which are releasably retained by the walls of each portion of the resilient plastic housing. When the housing portions are mated, the inserts are fixedly retained. If damaged by cross-threading, the insert can be easily and inexpensively replaced. A coined detent surface on an exposed portion of the insert is engaged by another coined detent surface on the rigid support. A thumb screw holds the detent surfaces together, and allows for changing the position of the apparatus. All components including the printed circuit board are supported by the chassis which is supported only by the housing. Thus the plastic housing provides vibration and shock attenuation for the chassis and its associated components.

Abstract: A rotor for the high voltage distribution system of an internal combustion engine, the contact member of the rotor being movable relative to the rotor shaft for a desired advance-retard characteristic. The rotor itself does not move relative to the rotor shaft. The device is for use with electronic ignition systems and one function is to replace the mechanical advance provided in conventional breaker point type distributors by the centrifugal weights which rotate the entire cam and rotor assembly. A range of characteristics responsive to engine velocity and/or acceleration is provided for within the basic design.

Abstract: An improved preselector cavity arrangement and RF selectivity assembly includes a cast housing for the preselector with a plurality of interconnection apertures or slots, each being surrounded by a boss. Each boss is mated with a slot in an adjoining housing of an interconnected module for allowing input, output and injection connections to be made to the preselector without intermediate connections to the supporting printed circuit board. One adjoining housing may contain the RF amplifier with coupling and impedance matching to the amplifier output coil provided by a loop from the preselector input. The loop passes through the shielded aperture, couples to the output coil by passing around the coil form and then returns to ground on the preselector casting. The injection filter and tripler/mixer modules may be contained in other adjoining housings and also coupled to the preselector through shielded apertures. To minimize RF spray radiation no interconnections are made via the printed circuit board.

Abstract: Circuitry utilizing either composite sync or separated sync data provides self-stepping capability for the vertical scan of a CRT alphanumeric display. A counter counts horizontal sync pulses for varying the vertical scan rate between rows of characters in steps, and is synchronized with the beginning of each frame by the vertical sync pulse. Alphanumeric data can be displayed with any desired spacing between rows without change of character format and with minimum effect on the size of the displayed characters.

Abstract: Matched semiconductor junctions on a single integrated circuit chip are connected in a current mirror arrangement to provide a low power AC level detector arrangement using only one resistor. Two transistors are identical except for junction area and each is in series with a constant current source. Since all other physical characteristics are identical, when identical voltages are applied, the junction currents are related by the ratio of their areas. By fabricating the area of the second emitter-base junction to be less than the area of the first, a portion of the current from the second current source is diverted therefrom to the base of a third transistor, forcing the latter into saturation. Accordingly, when an AC input signal of at least threshold level is coupled to the base of the second transistor, the current in the second transistor is driven to the level of its source.

Abstract: A non-reciprocal signal path for RF over a broadband frequency range is provided by an isolator comprising two coils or meshes positioned at 90.degree. to each other adjacent at least one gyromagnetic or ferrite disc which is magnetically biased by a static magnetic field. Each coil is tuned by a parallel capacitor, each coil and capacitor having one end grounded to a surrounding electromagnetic shield. A resistive unilateralizing element is coupled between the input and output terminals and, being essentially non-reactive, provides the broadband characteristic. The energy from the reverse direction is dissipated externally in the resistive element. A magnetic return path of a high permeability material allows the use of smaller biasing magnets and reduces the effects of external magnetic fields.

Abstract: A switching amplifier includes a pulse width modulator for converting a bipolar input signal, which may be a speech signal, into a train of unipolar pulses having durations which vary with the instantaneous absolute amplitude of the input signal. The pulses control the energizing of a series switch which supplies current to a switching bridge circuit. The switching arms of the bridge circuit are controlled by the polarity of the input signal. Another switch and several diodes are used to provide a path for output current when the series switch is open. The output current is filtered to remove fluctuations at the switching rate, and applied to a load. The amplified output voltage signal accurately follows the input signal, and the efficiency of conversion of DC power to AC output power can approach 100 percent, limited only by switching and filtering losses. A single polarity DC supply, such as a battery, is used to provide bipolar output current to an ungrounded load.

Abstract: When the load current of a voltage regulator rises above a safe value for sustained operation, a limiting circuit is activated to prevent further rise. At the same time, a capacitor in a timing circuit is being charged so that if the overload condition continues beyond a predetermined amount, the capacitor voltage will trigger a latching circuit to shut off the regulator. The regulator is reset by merely turning off the supply long enough to allow the capacitor to discharge.

Abstract: An improved input/output transducer having an arrangement for changing the frequency response of a small speaker when it is used as a microphone provides optimum response for both requirements. When utilized as a microphone, most of the apertures in the speaker enclosure wall are covered by a movable grille and the remaining ones are appropriately damped. This provides an acceptable frequency response with lowered sensitivity. When used as a speaker, most of the enclosure apertures are completely clear, although a small number may remain damped, providing sufficient output in speaker mode.

Abstract: Multiple resistance elements are mounted in parallel pairs around the inside curved wall of the assembly housing. Multiple cylindrical contacts in a planetary arrangement are rotated by a friction drive surface mounted on the control shaft. Each cylindrical contact rolls on one pair of resistance elements. The cylindrical contacts, by being movable shunts between the parallel strips, provide ganged multiple potentiometer or rheostat capability. No terminal is connected to any moving part. The diameter of the drive surface and the diameter of the cylindrical contacts determine the possible number of resistance elements per assembly. Shaft rotation for full range variation, thus vernier capability, is determined by the ratio of the drive surface diameter to the inside diameter of the housing.

Abstract: A housing for a mobile transceiver has integrally molded aligning and locking features to allow assembly without tools. As the metal support frame and attached printed circuit board enter the housing, short legs on the lower edge of the frame provide support and positioning for guiding the edges of the PC board into molded guide rails along the inner side walls of the housing and into molded locking clips on the inner front wall of the housing. The top rear of the housing is molded with a slight concave bow. The top and bottom rear edges of the housing have ramp portions for admitting the rear of the chassis. As the frame is forced home, a portion of the top rear of the frame pushes on the upper ramp, forcing the top of the housing to yield. Tabs on the bottom rear of the chassis ride up the lower housing ramp and are forced into slots in the housing bottom by the bias of the bowed housing top section.

Abstract: A vertical synchronizing signal for a CRT display is separated from a composite sync signal by combining in a NAND gate the composite signal and the output of a monostable multivibrator having a pulse width greater than the horizontal sync pulse width. When the vertical sync signal is not sufficiently high to trigger the sweep circuit, a sync signal sensor will allow an oscillator to free-run at a frequency very near the field rate. Vertical sync pulses of sufficiently high level are gated through the free-running oscillator, without oscillation, to the vertical sweep circuit where they are used to trigger a monostable multivibrator. The vertical hold control can be eliminated without endangering the CRT screen.

Abstract: A vent valve for electric energy cells requiring pressure relief capability for gases formed within the cells due to overcharging or other circumstances includes a cover plate for the internal structure of the cell which contains a central relief aperture. A vent cap is affixed to the cover plate with one or more vent ports being provided. A resilient seal is provided between the vent cap and the cover plate for controlling the release of the gases, the seal being die-cut of a suitable corrosion-resistant material and having two parallel plane surfaces which contact the cover plate and the closed end of the vent cap when the cap and plate are joined. The seal is preferably of a polygon configuration and its vertices contact the walls of the cap for fixed positioning. The vent path for the gases is through the aperture in the cover plate, between the cover plate and the resilient seal, and out through the vent ports.