Abstract: A UHF television receiver tuner comprises a varactor tuned circuit coupled to an input electrode of a field effect transistor mixer through a serially connected RF coupling capacitor. A local oscillator signal is coupled to the input electrode of the field effect transistor mixer through an inductive loop whose inductance value is chosen such that proper impedance matching over the UHF band is achieved.

Abstract: A television receiver includes a video display for producing a video display image in accordance with a received television signal and a power supply responsive to an irregular current drain for perturbating the video display image. A telephone interface circuit coupled to the power supply is responsive to a viewer initiated dialing signal for completing a telephone connection with the corresponding telephone number in a manner so as to cause an irregular current drain from the power supply. The resulting perturbations otherwise present in the video display image are eliminated by a circuit cooperating with the telephone interface circuit for effecting a substantially uniform current drain from the power supply in response to the dialing signal.

Abstract: An electronic organ having a scanned keyboard manual (10) includes a keyboard latch (24) interposed between the scanning apparatus (12) and the organ keyers (26). The keyboard latch (24) comprises a gate (42) for comparing the serial data pulses, each of which represents a respective depressed key, produced at the output of the scanning apparatus (12) during each scan of the keyboard manual (10) with the serial data pulses produced during the immediately preceding scan for developing a control signal representing the detection of a depressed keyboard key during the on-going scan which was not depressed during the immediately preceding scan. An output circuit (52, 54, 56) is provided for continuously developing an output signal reflecting the keys depressed during the last scan in which a control signal was developed whereby the tone signals corresponding thereto are continuously sounded even though the keys have subsequently been released.

Abstract: Apparatus for producing a chorale or vocal effect in an electronic musical instrument comprises means responsive to the playing keys of the instrument for producing an indexing signal and means responsive to the indexing signal for sequentially developing a plurality of control signals. A programmable filter is responsive to each sequentially developed control signal for modifying the harmonic content of a tone signal to simulate a different vowel-like sound for producing a vocal effect consisting of a sequence of different vowel-like sounds as the keys are played. The modified tone signal may be coupled through a chorus generator to simulate a chorale effect and the programmed characteristics of the filter may be modulated to further animate the performance as well as being made responsive to a glide signal for producing two different vowel-like sounds in succession at two different pitches in response to a glissando or portamento command.

Abstract: A billboard video display system comprises a plurality of cathode ray tubes arranged in a predetermined configuration, each of the cathode ray tubes including a viewing screen characterized by a coarse color phosphor pattern. The electron beam generated by each of the cathode ray tubes is scanned across its respective viewing screen and modulated for developing a plurality of color picture elements. The picture elements so produced combine to form a selected billboard video display picture with the picture elements associated with each respective tube representing an unrecognizably small portion thereof.

Abstract: A varactor controlled television receiver tuning system is operable for tuning all VHF and CATV television channels in four frequency bands including the low VHF band extending between 54-88 MHz, the mid/high VHF band extending between 120-216 MHz, the CATV superband extending between 216-300 MHz and a CATV hyperband extending between 300-400 MHz. The tuning system comprises a plurality of identically configured resonant circuits each responsive to a pair of band switching signals for assuming a total inductance for tuning each of the four different frequency bands, each of the resonant circuits being alignable by adjusting a different variable reactance element in each frequency band.

Abstract: An adjustable yoke assembly for a CRT (cathode ray tube) is described for optimizing the orthogonality and concentricity between the yoke's horizontal and vertical fields in order to obtain a desired raster shape. The yoke assembly includes a liner which carries one deflection winding, a core which carries another deflection winding and which is mounted on the liner, and an adjustment ring which is mounted on the liner and fixed to the core. The liner includes at least one elongated member which projects radially outwardly from the liner so as to engage detent means, such as serrations, carried by a finger which projects outwardly from the adjustment ring. When the core is manually rotated on the liner to adjust the relative position of the deflection windings, the adjustment ring rotates with the core in a detented manner to provide accurate positioning of the core's winding and optimum orientation of the yoke's horizontal and vertical fields.

Abstract: An AC signal processing circuit fabricated on a single integrated circuit chip used in a television receiver is both defeated and the DC level characterizing its output terminal is controlled in response to a manually operable switch communicating with a single input pin of the chip. A control circuit comprising a pair of differential amplifiers fabricated on the chip is responsive to the switch for enabling the AC signal processing circuit or, alternatively, for inhibiting the circuit while simultaneously causing its output to assume a controlled DC level.

Abstract: An electronic musical instrument includes a programmed microprocessor for controlling selected functions of the instrument and a plurality of key and tab switches responsive to a scan control signal repetitively scanning the switches for developing a serial data signal defining operated key and tab switches during each of the scans. An interface circuit is interposed between the key and tab switches and the microprocessor for developing the scan control signal and for receiving the resulting serial data signal. The serial interface circuit includes means for converting the received serial data into a number of first multibit words each representing a depressed key and a number of second multibit words each bit of which represents the operational condition of a respective one of the tab switches.

Abstract: A tone source apparatus for an electronic musical instrument includes a sequentially addressable memory storing a plurality of waveform segment defining instructions, each instruction including a component representative of the amplitude variation, the time duration and the direction of change of the associated waveform segment. Output means comprising an adder-subtractor circuit and a latch is operated for accumulatively processing the stored amplitude variation representative components for producing a stepped output signal whose direction of slope is determined by the stored direction component. Control means interposed between the memory and the output means is selectively operable for modifying the stored amplitude variation components coupled to the output means for imparting a sinusoidal inflection to the stepped output signal.

Abstract: An automatic CRT tracking circuit for a television receiver includes an amplifier having adjustable gain and offset transfer functions for coupling a video signal to the cathode of the CRT electron gun. Feedback loops are used to adjust both the gain and offset transfer functions of the amplifier, either independently of each other or in a common mode, to compensate for changing cathode voltage versus cathode current characteristics such that a desired video signal versus cathode current relationship is achieved despite variations in the CRT.

Abstract: A television signal audio transmission system comprises transmission means for developing first and second stereophonically related audio signals and means for developing a third audio signal. The transmission means further includes circuitry for developing a composite baseband signal having a first component comprising the sum of the first and second audio signals, a second component comprising a double sideband suppressed carrier signal formed by amplitude modulating a 2f.sub. H subcarrier with the difference between the first and second audio signals, a third component comprising a pilot signal having a frequency f.sub.H and a fourth component comprising a 4f.sub. H subcarrier signal frequency modulated according to the third audio signal, where f.sub.H represents the horizontal scanning line frequency. The composite baseband signal may include a fifth component comprising an approximately 5.5f.sub.

Abstract: A television receiver includes an interface circuit enabling the production of on-screen displays of alpha-numeric type information in a selected color. The interface circuit is responsive to a blanking signal for reducing the red, green and blue video signals developed in response to a received NTSC color television signal below the blanking level of the television receiver. A digital signal representing selected alpha-numeric type information is coupled from a character generator to the interface circuit for increasing the potential at one or more of the electron guns of the receiver for producing a corresponding on-screen display in a selected color.

Abstract: A DC coupling reduction circuit for use in a television receiver having a DC restoration circuit comprises means for developing a dynamic adjustment signal by attenuating a video signal by a selected percentage, inverting the attenuated signal and low pass filtering the attenuated and inverted signal. The dynamic adjustment signal is combined with a viewer selected direct current black level reference signal to produce a combined signal which is coupled to the black clamp level determining input of the DC restoration circuit whereby the black level of the video signal is clamped at a potential which is a function of the video signal. Preferably, the cut-off point of the cathode ray tube of the television receiver is set at a level between the levels of the combined signals produced in response to a video signal representing a white image and a video signal representing a black image.

Abstract: Disclosed is a perforated circuit board with a linear arrangement of paired terminals through which jumper wires are inserted and which are positioned on each side of and adjacent to the perforations. The perforations permit flexible "breaking" of the circuit board into sections which may be oriented at any angle relative to one another while the machine-inserted jumper wires provide structural integrity and rigidity for the circuit board arrangement thus formed in addition to electrical coupling between adjacent board sections.

Abstract: A voltage controlled attenuator comprises a switching circuit operable for alternately coupling a capacitor to a source of input signal voltage and to a discharge circuit for first and second time intervals respectively, the duration of the second time interval being set in accordance with an applied control voltage. An output circuit includes apparatus for sampling the decayed input signal voltage developed by the capacitor following each of the second time intervals for developing an output signal comprising an attenuated representation of the input signal.

Abstract: A tuner includes a channel or target frequency selection means, a tunable oscillator, a tunable circuit means having at least one tunable circuit, and tuning means, responding to the target frequency select means, for automatically and individually tuning the tunable circuit. Typically the tuner includes several tunable circuits, which are tuned successively.The illustrated embodiments have three individually controlled varactor tuned circuits and a varactor tuned oscillator. To move to a new target frequency, the tuner locks the oscillator to the target frequency via a phase locked loop. This target frequency is inputted to the first varactor tuned circuit, and a microprocessor cooperating with a DC detector for sensing the output of the set of tuned circuits steps a voltage step generator which controls the first varactor tuned circuit while the tuning of the other varactor tuned circuits is held fixed.

Abstract: A horizontal width control circuit for use with an image display apparatus includes first and second variable inductors connected in series and shunt relationship respectively with a horizontal deflection coil. The inductance of the inductors are variable in opposite directions for controlling the extent of horizontal deflection through a relatively large range of values without detuning the horizontal deflection circuits.

Abstract: A method and electronic circuit are described for generating a sawtooth waveform for vertical deflection of a television receiver's cathode ray tube. The method is effected by a circuit which includes a single capacitor which is charged to develop the ramp portion of the sawtooth. In response to a vertical sync pulse, the circuit discharges the capacitor and compares the capacitor's discharge voltage to a predetermined threshold voltage. When the latter two voltages are substantially equal to each other, discharge of the capacitor is discontinued, thus generating a sawtooth waveform across the capacitor. The capacitor begins charging again to form another ramp voltage and is discharged on receipt of the next vertical sync pulse. The charge and discharge of the capacitor repeats as successive vertical sync pulses are received.

Abstract: An equalizer and decoder system compensating for multipath distortion in digital format signals sent by teletext, for example. The system loads demodulated data signals and a received reference signal into a charge coupled device clocked in real time by a clock circuit. Later, the reference pulse is clocked to a microprocessor which determines tap coefficients for a transversal filter to correct the multipath distortion in the reference signal. The data signals are then applied to a transversal filter weighted with the calculated tap weights. After filtering, signals are decoded by the microprocessor.In another embodiment a charge coupled device with tapped stages is used at one time for receiving the data signals in real time, and at a later time for part of a transversal filter.In a simplest embodiment, distortions are removed by the microprocessor itself, without any separate transversal filter.