Abstract: The present invention relates to a lighting unit having low and high light levels and employing an efficient arc lamp as the source of light during the high level setting. The unit employs a filamentary light source for the production of light during low light level operation, the filament acting as a resistive ballast for the arc lamp during high level operation. Practical embodiments operate in a conventional three-way light socket with the sequences being off, low, high and low, and off, low, high, and high.

Abstract: A lighting unit is described utilizing an energy efficient metal vapor arc lamp as the main source of light supplemented by a standby filamentary light source producing light when the arc lamp is being started, the filament thereof serving as a resistive ballast for the arc lamp under normal operation. The lighting unit is designed as a more efficient replacement for the incandescent lamp. The lighting unit includes a rectifier for conversion of 60 hertz ac to dc, and a dc energized operating network, including a ferrite transformer and a transistor switch. The operating network produces an output adapted to each operating state of the arc lamp, including the provision of a high ignition potential, a power boost for the lamp during the glow to arc transition, warm-up and ballasting provisions, and means for sustaining the arc during transients which reduce the line voltage.

Abstract: A novel and economical transformer is described for use in a static inverter in association with one or two switching devices, typically transistors. The transformer produces an output for control of the associated switching device(s) which changes in sense as a function of the flux level in the transformer core. The arrangement is applicable to a figure "8" flux configuration such as is achieved from two "E" cores, and requires only a single aperture located at the base of the common branch. Control is effected by a single primary and single secondary winding wound through the aperture. With two switching devices, two apertures are normally provided. The core which supports a figure "8" flux configuration may take other more economical alternatives such as "I" core, "T" core or a single "E" core.

Abstract: A gated multiple stage AGC amplifier circuit comprising a differentially connected transistor pair in each stage and employing a dc feedback network for maintaining a balanced current conduction in the transistors of each transistor pair for achieving maximum gain and dynamic range throughout the gated operation. The dc feedback network includes a bias capacitor, a dc bus coupling a dc bias voltage across the capacitor to each transistor pair, and bias control means responsive to transistor current conduction for supplying charge and discharge currents that are made equal to each other for maintaining a stable dc bias voltage across said bias capacitor that results in said balanced current conduction, said bias control means exhibiting impedance characteristics that maintain said stable bias voltage throughout the gated amplifier operation. The invention has particular application to the receiver of a pulse echo system wherein the amplifier is gated "on" to correspond with received echo pulses.

Abstract: An ultrasonic intrusion alarm system of the pulse-echo type transmits pulsed signals which are reflected by a reference surface. The resulting reference received pulsed signals appear as corresponding signals at the output of the system's receiver, which is gated on in coincidence with the arrival of said reference signals and is gated off at essentially all other times for minimum power consumption, the output signal state of said receiver being employed to cause the generation of an alarm signal upon the occurrence of an intrusion. The receiver includes an AGC amplifier network which exhibits a threshold voltage level that is a function of the signal strength of said reference signals which level is compared with the amplified received signals whereby said alarm is generated when said threshold level fails to be exceeded, such as due to an interruption of said signals.

Abstract: The present invention relates to a lighting unit utilizing an energy efficient arc lamp as the main source of light supplemented by a standby filamentary lamp, the filament serving as a resistive ballast for the arc lamp during normal operation. The lighting unit is designed for functional similarity to an incandescent lamp, the filament providing immediate illumination when the lighting unit is first energized and continuing illumination until the arc lamp itself produces light. In accordance with the invention, if the arc lamp does not start within a predetermined period, the application of starting potentials produced through operation of a solid state switch and a high frequency step-up transformer is discontinued and the lighting unit rendered inactive. Exemplary means includes a positive temperature coefficient thermistor responsive to the temperature rise of the solid state switch.

Abstract: A FM local oscillator circuit suitable for integrated circuit fabrication, the frequency of which responds to a first current component for reducing frequency drift of a tuned frequency as a function of temperature and to a second current component for providing automatic frequency control of said tuned frequency. The circuit comprises a cross coupled differential pair of transistors, adapted to be coupled to a tuned circuit manually tunable over a given frequency range, which exhibit a negative conductance substantially controlled by said first current component for sustaining oscillations over said given frequency range and which further exhibit a variable capacitance controlled by said second current component for providing electronic fine tuning of the oscillator circuit.

Abstract: A novel transformer is described for use in a static inverter in association with one or two switching semiconductor devices. The transformer produces an output for control of the associated switching device(s) which changes in sense from conduction aiding to conduction inhibiting as a function of the flux level in the transformer core. The invention is applicable to single loop cores, such as are assembled from two "U" cores. Control is effected by a primary and secondary control winding wound through an aperture pair, the aperture pair being oriented for "neutrality" of the second control winding to the main flux. The aperture pair creates a five branch magnetic path which permits optimizing the control voltage applied to the associated semiconductor devices both to enhance the switching efficiency when the switching device is initially turned on and to reduce stresses on the switching device by precluding transformer saturation when the switching device is turned off.

Abstract: A detector circuit for detecting AM and FM signals adapted particularly for integrated circuit fabrication which has a circuit configuration that provides highly stable operating characteristics for both AM and FM operation and is responsive to an increased dynamic range of AM signals. The circuit is uniquely designed to exhibit minimal bias and output voltage variations in the presence of unavoidable IC process changes from one circuit to another and ambient temperature changes, by employing an arrangement of circuit components that readily compensate for such changes.

Abstract: A static inverter employing an inductor and an electrical gain element for intermittent assymetric energization of the inductor from a dc source is described. Reliable intermittent operation of the gain element, typically a power transistor, is achieved by use of three feedback windings which in response to saturation of a branch of the core of the inductor but before full core saturation, discontinue regenerative feedback and then apply degenerative feedback. This turn off mechanism protects the transistor from high current stresses. Passive means are provided such as a capacitor for momentarily storing the energy or diode means for coupling the energy back to the source or to the load to protect the transistor from the high voltage surge and the energy release when current flow in the inductor is interrupted. Energy stored in the capacitor may be used for transistor commutation.

Abstract: The present invention relates to an AM-FM receiver suitable for integrated circuit fabrication and having improved mode conversion means. The AM-FM receiver had a d.c. coupled IF broadband IF amplifier comprising a plurality of stages of emitter coupled transistor pairs. A d.c. feedback network is provided to balance the individual stages and to generate a control potential for further use in mode conversion. In the FM mode, the IF amplifier operates with a high, stable gain at the FM IF frequency with gain reduction for noise suppression purposes below the FM IF frequency. Frequency dependent noise suppression is provided by a capacitance associated with the degenerative network. In the AM mode, the IF amplifier operates at a controllable, medium gain with the degenerative effect on IF gain restored at the AM IF frequency by the addition of capacity to the degenerative network.

Abstract: Electronic apparatus is disclosed suitable for integrated circuit fabrication and comprising shunt voltage regulation. The electronic apparatus may be a radio receiver which uses an unregulated current source for its supply voltage. The power amplifier of the audio amplifier has a pair of conventional large area push-pull output transistors which are connected in shunt with the supply. In accordance with the invention, shunt voltage regulation of the supply voltage is achieved by sensing a change in the supply voltage using a zener diode for a voltage reference and then altering the idling current in the output transistors in response to changes in current flow through the zener diode. In consequence of increases in idling current, the output stages shift from class B toward class A operation and shunt regulate the supply voltage. The zener diode is arranged to provide both stabilization of the full supply voltage and the centering voltage of the push-pull output amplifier.

Abstract: An FM tuner having an improved automatic frequency control circuit and designed for use in an AM-FM receiver is described. The tuner employs a mixer transistor and an oscillator transistor connected in circuit so that they form a single series path across the bias source. This feature permits one to control conduction in both transistors by control of one and thus simplifies both biasing and mode conversion. Preferably, the transistor bias source and the source of AFC control potential are consolidated to save decoupling components. When the base of the mixer transistor is connected to the source through a low d.c. impedance, the AFC potential is transferred (less the mixer junction drop) to the collector of the oscillator transistor, where it provides sensitive automatic frequency control action. The circuit design uses a minimum of components.

Abstract: A detector for AM or FM signals is described. The detector employs a differentially connected emitter follower pair to which an in-phase and a phase-shifted signal are respectively applied. The emitter follower pair produces an output waveform with controllably spaced zero crossings which is the "greater of" the applied waveforms. For FM operation, the phase shift is made linearly frequency dependent, being in quadrature at resonance. In FM operation, the zero crossings are sensed to produce a succession of variable width unidirectional pulses whose widths are proportional to the frequency deviation. Amplitude variations in the variable width pulses may then be removed and integration in a filter with an audio frequency time constant recovers the FM modulation information. For AM operation, a phase shift of 180.degree. is used, producing full wave rectification. The AM information is then recovered from the rectified signal using the same integrating filter used for FM.

Abstract: The present invention relates to an AM-FM receiver of the superheterodyne variety having a novel bias supply circuit wherein a common filter capacitor may be used for the bias supply, the AGC function in AM operation, and the AFC function in FM operation. The B+ bias is supplied through a controllable current source which adjusts the bias in accordance with the detector output. In the FM mode setting, automatic frequency control of the local oscillator is provided by bias adjustment. In the AM mode setting, automatic gain control of the IF amplifier and of the AM section of the tuner is provided by bias adjustment. The invention has preferred application to integrated circuit fabrication.