Rca Inc.

Patrick D Griffis

Abraham E Rindal

A frequency translation phase-locked loop (PLL) is provided for detecting the audio information from a received television signal. The PLL includes a switching arrangement which, in a first position causes the loop to process the IF picture and sound carriers for detecting the audio information in an intercarrier type of detection method and, in a second position causes the loop to process the IF sound carrier for detecting the audio information without the use of the received picture carrier, in a 'separate' (split-sound) type of audio detection method.

Frequency translation phase-locked loop for separate or intercarrier

A system for synthesizing stereophonic signals from an audio information signal source is provided. The system includes a transfer function circuit for producing a modulated signal which varies in amplitude as a function of frequency in response to the audio signal, first and second amplifiers for providing amplified output signals, and a switch circuit for coupling selected ones of the audio signal and the modulated signal to the inputs of the first and second amplifiers. In a first position, the switch circuit causes the first and second amplifiers to operate in a matrix mode for matrixing the input signals to provide first and second synthesized stereophonic output signals, and in a second position, the switch circuit causes the amplifiers to operate in a non-matrix mode with respect to the input signals supplied thereto for providing an amplified audio output signal.

Switching arrangement for a stereophonic sound synthesizer

A frequency translation phase-locked loop (PLL) is provided for detecting the audio information from a television signal. The PLL includes a mixer and a phase detector, responsive to the intermediate picture and sound carriers respectively, which carriers are amplified by a single IF amplifier. A first filter is coupled between the output of the television receiver tuner and the input of the IF amplifier and has a frequency response for passing the picture and sound carriers. The input of the mixer is coupled to the output of the IF amplifier and is substantially responsive to the amplified picture carrier. The phase detector has a first input also coupled to the output of the IF amplifier and is substantially responsive to the amplified sound carrier and a second input coupled to the output of the mixer. A second filter coupled to one of the first and second inputs of the phase detector has an amplitude versus frequency response which provides a predetermined attenuation at the frequency of the picture carrier and substantially less attenuation at the frequency of the sound carrier. A lowpass filter coupled to the output of the phase detector provides the detected audio information.

Frequency translation phase-locked loop television sound detection system

An arrangement for suppressing the audible effects of operating supply voltage transients developed when a sound reproducing system including a gain controlled audio amplifier is initially energized and de-energized. A control path supplies the amplifier with a gain (volume) control voltage of positive and negative senses corresponding to maximum and minimum sound volume. A first capacitor is coupled between the control path and a source of positive operating voltage from which the gain control voltage is derived. A normally non-conductive threshold conduction device and a second capacitor are coupled in series with the first capacitor between the control path and ground. The threshold device is biased to be rendered conductive for coupling positive-going supply voltage transients away from the control path via the second capacitor when the system is initially energized, thereby suppressing the audible effects of the positive transients. Negative-going supply transients developed on the control path when the system is de-energized are in a direction corresponding to minimum volume and are essentially inaudible.

Volume control signal coupling circuit in an audio signal processing

First and second sound channels are provided for processing audio signals. Each sound channel includes means responsive to a D.C. control voltage for controlling the volume of the audio output signal of the channel. A volume control potentiometer is coupled across two terminals of a source of supply voltage and a D.C. volume control potential is developed at a tap of the potentiometer. The volume control potential is applied to a control electrode of a controlled current path. The controlled current path includes the parallel combination of a first voltage divider and a second, variable voltage divider. A tap of the first voltage divider is coupled to the D.C. control input of the first sound channel, and a tap of the second voltage divider is coupled to the D.C. control input of the second sound channel. By adjusting the second, variable voltage divider, the control voltage provided by the second voltage divider may be set to equalize the D.C. volume control characteristics of the two sound channels.

Matching volume control characteristics for two channels

A semiconductor package is provided in which the semiconductor element is bonded to a slab of metal and is encapsulated in a body of insulating epoxy. Lead terminals are connected to the semiconductor element within the body and extend out from one end of the body. The metal slab extends out from the body from the same end as the lead terminals and in a plane which is parallel to that of the terminals, thereby forming a heat sink tab for the device. The package may be rigidly mounted on a printed circuit board by inserting the lead terminals and the heat sink tab into respective holes in a printed circuit board and soldering the terminals and tab to copper foil on the board. The solder connection of the heat sink tab to the copper foil provides an excellent thermal contact between the tab and the foil, in addition to providing a rigid support for the device.

Semiconductor apparatus with integral heat sink tab

An integrated circuit heat dissipator is provided which will additionally hold the integrated circuit in a printed circuit board prior to soldering. The heat dissipator is comprised of a single elastic piece of metallic material having oppositely facing sides joined by a fold at the top. A tab is located at the bottom of each of the sides which is suitable for insertion into a printed circuit board. The tabs have a width which allows them to contact only the heat-conducting pins of the integrated circuit. The heat dissipator is mounted adjacent to the integrated circuit with one of the tabs contacting the heat-conducting pins. The elastic material gives the heat dissipator a spring-like property which causes the tabs to press outwardly from each other when inserted in a board so as to fixedly hold the heat dissipator and the integrated circuit in the printed circuit board prior to soldering.

Integrated circuit heat dissipator

A system is provided which synthesizes stereophonic sound by developing two separate sound channels from a single monophonic sound source. A synthetic stereophonic sound system constructed in accordance with the principles of this invention may be advantageously utilized in combination with a visual display such as a television receiver. A monaural signal is applied as the input signal for a transfer function circuit of the form H(s), which modulates the intensity of the monaural signal as a function of frequency. The intensity modulated H(s) signal is coupled to a reproducing loudspeaker, and comprises one channel of the synthetic stero system. The H(s) signal is also coupled to one input of a differential amplifier. The monaural signal is coupled to the other input of the differential amplifier to produce a difference signal which is the complement of the H(s) signal. The difference signal is coupled to a second reproducing loudspeaker, which comprises the second channel of the synthetic stereo system. In accordance with a preferred embodiment of the present invention, a stereo synthesizer is utilized as the sound reproducing system of a television receiver, with the reproducing loudspeakers located on either side of the kinescope. The amplitude -vs- frequency response curves of the two output channels have crossover points at which the amplitudes of the two response curves are equal, which effectively centers sounds at these frequencies between the loudspeakers. Two crossover frequencies are chosen to occur at approximately the frequency of peak intensity of the human voice, and at the center frequency of the second (articulation) formant frequencies of the human voice so as to effectively center voices on the kinescope while preserving the ambience effect of other, more randomly distributed sound signals. Centering the second formant frequencies also provides increased quality in the reproduction of speech sounds.

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Indianapolis, IN, United States of America

Patrick D Griffis