Abstract: A plural-output switched current source, as may be used to provide current drive to inidividual display segments of an LED display. Each respective current source output is selectively operable from a respective low level I.sup.2 L signal source. Means are provided to reduce the tendency of the selective operation of one LED display segment to affect the brightness of the remaining LED display segments.

Abstract: A remote control system utilizing a portion of a television receiver system to control appliances external to the television receiver. A specific embodiment is shown for controlling a telephone through the television remote control unit. The viewer answers or originates telephone calls by operating the television remote control unit. In an alternate embodiment, the signal carrier from the control unit to the television is modulated in order to transmit voice signals. Further appliances may be controlled through the telephone line or by other connections to the television receiver.

Abstract: A bridge amplifier is provided wherein one end of a load device is driven by a first amplifier and the other end of the load device is driven by a second amplifier. The second amplifier is an inverting amplifier comprising P and N-channel field-effect transistors, having complementary symmetry conduction characteristics. The input to the second amplifier is directly coupled to the output of the first amplifier.

Abstract: A switching circuit provides first and second output signals to respective first and second output load devices that are switched responsive to an input signal. The switching point of the first output signal is set relative to the switching point of the second output signal to achieve "make before break" or "break before make" switching of the first and second output load devices. In particular, the switching circuit uses an emitter coupled differential amplifier having first and second differential output signals. Each of the first and second differential output signals is received by a respective first and second current mirror amplifier for converting each differential output signal to the respective first and second output signal.

Abstract: The output stage of a quasi-linear amplifier employs a p-channel and an n-channel FET with their sources at relatively positive and relatively negative operating voltage rails to drive a load from their drain-to-drain connection, so that despite their being enhancement types full rail-to-rail output voltage capability can be obtained without need for bootstrapping. Input signal voltage and direct-coupled feedback voltage are applied to the gate-to-gate connection of p-channel and n-channel source-followers with their respective sources direct-coupled to the gate of the p-channel FET in the output stage and to the gate of the n-channel FET in the output stage, respectively, and with their respective drains connected to the relatively positive operating voltage rail and to the relatively negative operating voltage rail, respectively, in a representative driver stage.

Abstract: A complementary symmetry inverter comprising two field effect transistors and a current mirror amplifier. A constant bias current is supplied to the master path of the current mirror amplifier. The slave path of the current mirror amplifier and one of said field effect transistors are connected to form a switched current source in series with the other of said transistors. The switched current source limits the peak value of the switching current pulse in the inverter in fixed relation to the current in the master path of the current mirror amplifier when the inverter switches between logic states. The switched current source also limits the current between the inverter output and an external device.

Abstract: A system for use in battery powered alarm equipment for self-testing such battery for a low voltage and a high series resistance condition, and particularly for use in systems which utilize a starting capacitor in combination with the battery to provide a high starting current to the alarm annunciator. For periodic battery tests, a resistor is selectively connected across the battery and the resulting voltage drop at the battery terminals is compared to a reference voltage supply. Energy stored in the starting capacitor is prevented from discharging through the battery test circuit by a transistor switch operated in the inverse mode for disconnecting the starting capacitor from one of the battery terminals during such battery tests so that substantially no current is supplied from the starting capacitor through the test circuit.

Abstract: A current driver circuit using a two-level current source for switching PIN diodes. The driver is responsive to a binary signal control voltage for providing a respective forward-bias current or reverse-bias voltage. The two-level current source, responsive to output voltage, is included in the driver circuit to supply one of two current levels when the driver is conditioned to forward-bias the diode. When the output voltage is below a predetermined threshold value, a first level of current is supplied; when the output voltage is above the predetermined value, a second level of current, generally larger than the first current, is provided. The disclosed technique reduces peak instantaneous power dissipation in the driver by avoiding the simultaneous condition of high voltage and high current.

Abstract: An input signal to a buffer circuit is applied via the emitter-to-base junction of a transistor to a circuit which includes at least one additional semiconductor junction and a current source. The collector of the transistor connects to a second current source and to the buffer circuit output terminal. When the input signal exceeds a threshold value, determined by the number of semiconductor junctions in the circuit including the emitter-to-base junction, the transistor turns on and its collector current, which exceeds the capacity of the second current source, flows via the buffer circuit output terminal to the load circuit.

Abstract: A differential-input differential-output transconductance amplifier is connected so the potential applied to a first of its input terminals, its envelope, or portions of its envelope, is followed by the potential at the second of its input terminals, either continuously or at selected times. To this end the balanced variations in the output currents of the transconductance amplifier are converted to a single-ended signal applied to the input electrode of transistor means, the output electrode of which is connected to the second input terminal of the transconductance amplifier for completing a direct-coupled feedback loop. Modifications of the basic circuit provide potential followers, voltage amplifiers, peak detectors, envelope detectors, and sample-and-hold circuits.

Abstract: A voltage comparator comprising first and second transistors of a first conductivity type receiving a current at an interconnection of their emitter electrodes has the collector of the first transistor connected to the base of a third transistor of a second conductivity type complementary to the first. Reference and bias potentials are applied respectively to the emitter of the third transistor and to the base of the second transistor; and input signal voltages to be compared to the bias potential are applied to the base of the first transistor. Input voltage swings to the reference potential are prevented from depriving the first transistor of sufficient collector potential to support flow of current from its collector to the base of the third transistor. This is done by inserting resistance between the source of input voltage and the base of the first transistor.

Abstract: An output transistor in common-emitter amplifier configuration is thermally coupled to means for generating a temperature-compensated component of bias potential. This bias potential is indirectly applied to the base electrode of the output transistor to provide for temperature-stabilized idling current flow in its collector-to-emitter path. More particularly, the bias potential is applied to the non-inverting terminal of a high-gain differential-input amplifier having its output terminal direct coupled to the base of the transistor and direct coupled to its inverting input terminal for regulating the quiescent potential at its output terminal to equal the bias potential. The differential-input amplifier has an input signal applied to one of its input terminals. In response to signal excursions in one sense, the differential-input amplifier drives the output transistor into increased conduction.

Abstract: The collectors of a pair of transistors operated quasi-linearly in push-pull are coupled to their load by an autotransformer winding, center-tapped to receive operating potential. The configuration simulates a full-bridge amplifier with operating potential twice as large, insofar as maximum output power capability is concerned.