Abstract: An I.sup.2 L programmable read only memory (PROM) output circuit has a selectable dual non-inverting input differential amplifier with each non-inverting input connected to a different column of memory elements. In the read mode the circuit operates at very low power levels and down to 1 volt. To program the memory elements, the circuit includes two selectable programming current sources which self extinguish as soon as the memory element being programmed changes from its unprogrammed to its programmed state. Switching between the read and program modes is accomplished merely by changing the voltage on the B+ terminal; 1-3 volts for read and 9-12 volts for program.

Abstract: A portable radio transceiver and mobile mount housing are disclosed which utilize a switchless connector for connecting the portable unit to an external antenna which is electrically coupled to the mobile mount. In the preferred embodiment, the portable radio is equipped with an internal antenna which is either coupled to an electrical contact on the exterior of the portable unit adaptable to making electrical contact with a similar contact on the inside of the mobile housing when the portable radio is inserted therein. The internal antenna in the portable unit is shielded by the metallic mobile mount housing which obviates the need to disconnect the same. In one embodiment the contact disposed on the portable unit exterior is connected to a predetermined point on the internal antenna for impedance matching with the external antenna when the portable unit is inserted into the mobile mount housing.

Abstract: A reduced power consumption low battery indicator comprising in the preferred embodiment a transducer driver which drives a transducer to provide an audible alert. A microprocessor is used to generate a squarewave signal to power the transducer driver whenever the battery is depleted to a first predetermined level. A first low battery sensor is used to determine when the battery is depleted to the first predetermined level and generates a signal which is directed to the microprocessor to commence generation of the signal to drive the transducer driver. A second low battery sensor is used to determine when the battery is depleted to a second predetermined level and generates an output signal which is directed to the transducer driver which then drives the transducer at a lower power consumption rate.

Abstract: A pocket clip suitable for attaching a personal paging receiver to an article of clothing has an integral character display. The pocket clip has a rigid lower housing part, and a plastic upper housing part containing the display and a circuit board with display decoder/driver circuitry. A conductive elastomer electrically connects the circuit board to the display while a flex circuit connects the circuit board to the paper. Bayonet tabs on the lower housing mate with slots in the upper housing to slideably connect the upper and lower housing parts. In one embodiment, the pressure necessary to clamp an article of clothing between the pocket clip and the pager is generated by a pawl, pivotally attached to the clip, with compressed springs positioned between the pawl and the clip. In another embodiment, the clamping pressure is generated by a torsion spring. An optional integral switch is also described.

Abstract: The present invention in the preferred embodiment comprises a plurality of current mirror circuit stages connected together for amplifying a first input signal and generating an output signal. A shunt path circuit is connected to the first stage of the plurality of current mirror stages and when activated by a second input signal shunts a portion of the first input signal to ground, thus reducing the current flow into the plurality of current mirror stages. During normal operation, when the shunt path circuit is inactivated, the last stage of the plurality of current mirror stages functions as a switch and passes all of the amplified first input signal. However, during the low power consumption mode, when the shunt path circuit is activated, the last stage of the plurality of current mirror circuit stages functions as a current mirror circuit and passes current at a considerably reduced level.

Abstract: A backlighted liquid crystal display (LCD) assembly has a thin phosphorescent layer positioned between the display and the light source to provide an even distribution of light intensity across the viewing surface of the display. The phosphorescent layer includes a phosphor powder mixed into a resin. The mixture is molded into a thin sheet and then cut to size. The phosphorescent layer and an optional disiccant layer may be encapsulated between sheets of acrylic film. The phosphorescent layer may also include a phosphorescent coating that is applied to the rear surface of the LCD or to the front surface of the light source.

Abstract: A backlighted display system includes a liquid crystal display, a flat light guide behind the display, and light emitting diodes (LED's). The light guide is a molded slab of clear polycarbonate material with two planes depressed into its rear surface. Four segmented bordering surfaces are approximately arcuate in shape. The depressed planes, the segmented bordering surfaces, and the rear surface are coated with a reflective white paint. LED holders are integrally molded with the light guide. A central portion of the front surface is optionally textured. The display system provides thin construction with even light distribution across the width of the display, low power consumption, and good outdoor visibility at dusk or dawn.

Abstract: Apparatus for discharging accumulated electrostatic charge from the human body includes a conductive ring to be worn on a finger. A first connector is attached to and electrically connected to the conductive ring. A cable with a mating connector plugs into the first connector. A second connector at the other end of the cable is connected to ground. A series resistor, located in the mating connector housing, limits current flow to a safe level in the event the user comes into contact with a high voltage high current source.

Abstract: A receiver for receiving and demodulating FSK modulated data signals has improved sensitivity over substantial frequency offsets between the transmitter and receiver local oscillator, and low spurious electromagnetic radiation. A quadrature coupler splits the received signal into in-phase and quadrature phase signals which are then mixed down to baseband, filtered, and limited. An RC circuit at the output of a four flip flop demodulator averages the flip flop output signals. A voltage comparator outputs a logical 1 if the voltage at the output of the RC averaging circuit is greater than one-half the supply voltage; otherwise the comparator outputs a logical zero.

Abstract: An improved electronic clip-on lead is disclosed. It is comprised of an elongated shaft suitable for electrical connection having a front spring finger extending from one end. A rear bracing member is positioned behind and parallel to the front spring finger by a support structure which fixes the displacement of the rear bracing member to the front spring finger.

Abstract: A low power, fast start up time crystal oscillator circuit has an amplifier portion powered from a one cell battery. The input stage of the amplifier portion is a common emitter amplifier circuit. A second stage includes a dual collector current mirror circuit having a current established at 3 times the input stage current. The output stage includes a current mirror circuit having a current established at 4 times the second stage current. A negative D.C. feedback circuit biases the amplifier portion. A single transistor interface circuit boosts and limits the output of the amplifier portion and permits the oscillator to drive other circuits that operate at higher voltages than the amplifier battery voltage.

Abstract: A signal processing circuit with enhanced response time includes a data limiter circuit having an input and an input capacitor having one terminal coupled to the input. A first selectively actuable voltage clamping circuit responds to a first comparing circuit and is coupled to the input for preventing the voltage at the input from exceeding a predetermined upper voltage. A second selectively actuable voltage clamping circuit is responsive to a second comparing circuit and is coupled to the input for preventing the voltage at the input from decreasing below a predetermined lower voltage.

Abstract: An RF receiver having a coupling capacitor connected between the back end of the receiver and the input to a data limiter circuit, a battery saver strobe feature which periodically turns the receiver ON and OFF and a precharge circuit for precharging the coupling capacitor. The receiver further includes a reference voltage stabilization circuit which prevents a received signal from reaching the output of the back end of the receiver during the precharging of the coupling capacitor in order to minimize the voltage offsets from the desired unmodulated carrier frequency reference voltage which results in erroneous data being decoded by the decoder portion of the RF receiver.

Abstract: A radio receiver from antenna to detector designed to be realized substantially on an integrated-circuit chip comprises a single tunable oscillator and a plurality of mixers. An input signal from an antenna is connected as an input to a first mixer and mixed with a signal derived from the oscillator. The signal may be taken directly, may be multiplied to a desired level or may be divided to a desired level. A particular output from the first mixer is selected by a first tunable filter. The output of the first tunable filter is taken as an input to a second mixer where it is mixed with a second signal derived from the oscillator. The process of mixing and application of the mixed signal to a tunable filter to select a desired frequency is continued as needed until the signal is reduced to a desired intermediate frequency range where it is amplified as needed to a level sufficient to drive a discriminator.

Abstract: A modular transducer mounting arrangement includes a substantially planar support plate. An aperture having an angular bevel is provided in the support plate such that a loudspeaker may be positioned in the bevel to allow sound to exit from the loudspeaker in a manner which is substantially unobstructed acoustically. An adhesive shock absorbing pad is attached to the rear of the support plate for isolating the loudspeaker microphone and support plate from mechanical shock. This creates a free floating and reliable transducer mounting assembly which provides shock isolation and easy serviceability.