Abstract: An improved loop current supply circuit including a first amplifier connected to a source of bias voltage. The first amplifier is further connected to a subscriber loop circuit through the tip and ring conductors. The first amplifier receives the bias voltage and supplies loop current to the loop circuit. A second amplifier connected to the tip and ring conductors outputs a voltage representative of the amount of current in the subscriber loop. When the output voltage of the second amplifier becomes greater than the bias voltage, a loop voltage network connected to the second amplifier and to the bias voltage source shunts the bias voltage from the first amplifier, decreasing the current in the loop circuit.

Abstract: Circuitry for supplying power to low-level DIALER portions of a telecommunications integrated circuit device comprises a PNP current sourcing transistor mirrored to a bypass transistor. The bypass transistor is coupled across the TIP and RING terminals of the subscriber line so as to maintain current flow sufficient to prevent the central office from "dropping out". A sensing transistor drives a current sink coupled to the current sourcing transistor in order to prevent that transistor from dropping into saturation and degrading the necessarily high impedance level that must be presented across the subscriber line. Saturation is prevented through the operation of a circuit loop that includes the base-collector junction of the current sourcing transistor, the emitter to-base junction of the sensing transistor, and a voltage offset element.

Abstract: A method and system for detection of authorized connections to a telephone line where such connections are for the purposes of intercepting voice or data messages. The original or base line impedance would be measured by the system in response to the entry of a special code. The base line is stored in memory and used for subsequent impedance comparisons.

Abstract: An arrangement for connecting an array of individual electronic elements into a readily expandable matrix. The arrangement comprises a plurality of matrix slices with each slice including a set number of electronic elements as well as a row and a column buffer. The electronic elements of each matrix slice are diagonally connected to the elements of the adjacent matrix slice.

Abstract: This invention is a device which permits the percentage of real time consumed by software tasks of a telecommunications switching system or other process controller to be measured and displayed on a percentage meter. The relative percentages of different real time tasks are displayed by the relative intensities of particular lamps mounted on a control panel of a meter. Non-standard, user defined, software tasks may be selected for display on the meter. Software tasks which over-shoot a predetermined amount of time provide an indication of this by lighting one of a number of different lamps. Each of these lamps measures a predetermined amount of over-shoot time.

Abstract: A three-port conference circuit for use in a pulse code modulated communication system including a first speaker register including an input connected to a telephone system information memory output and including an output, a second speaker register including an input connected to the telephone system information memory output and including an output and a conference adder connected to the first and second speaker register outputs via inputs and including an output connected to a sample inverting circuit of the telephone system. The conference adder adds talking samples by means of an included eight-bit floating point adder.

Abstract: An improved AC impedance matching arrangement including a first amplifier connected to a subscriber loop through the tip and ring conductors of a subscriber line circuit. The first amplifier is arranged to supply loop current to the subscriber loop through first and second resistors. Each resistor having a set DC value. A second amplifier connected to the tip and ring conductors is arranged to develop and output a signal responsive to AC signals applied to the tip and ring conductors from the subscriber loop. A feedback circuit connected to the second amplifier is arranged to receive the second amplifier output signal and develop and output to the first amplifier an impedance matching signal. The impedance matching signal raises the impedance seen by the tip and ring conductors above the set DC value of the first and second resistors.

Abstract: An electronic telephone instrument circuit capable of dialing (address signaling) in either pulse or tone mode. The circuitry permits the placement of a call through a rotary dial only system into a second network that is of a tone only nature. The included circuitry has very high return loss and relatively high level of tone capability and is designed to function with a variety of types of dialer integrated circuits. The present circuitry provides part of its DC current supervision while in the voice mode through the included tone amplifiers circuit thereby minimizing components and reducing current load through the voice network.

Abstract: An improved offhook supervision circuit including an amplifier connected to a subscriber loop through the tip and ring conductors of a subscriber line circuit. The amplifier is arranged to develop and output a loop voltage signal representing the level of the DC signals applied to the subscriber loop circuit. A comparator device has a first input connected to the amplifier and is arranged to receive the loop voltage signal output by the amplifier. A second input of the comparator device is connected to a reference voltage device which outputs a predetermined reference signal voltage. Any significant reduction of the DC signal level on the loop circuit will cause the loop signal voltage output by the amplifier to fall below the reference signal voltage. An offhook signal is then output from the comparator device to a control device signaling an offhook condition.

Abstract: A filter adapter for a connector plug mounted to an inner surface on electromagnetic interference shielding enclosure wall and including a plurality of connector pins. The adapter may be inserted between the connector plug and the enclosure wall to engage each of the connector pins passing therethrough and establish an electrical connection between the pin and the enclosure wall through an electromagnetic interference reducing capacitor, this without the necessity of introducing additional electrical contact points in the conductors as they pass through the enclosure wall.

Abstract: This circuit provides for synchronizing duplex copies of processor controllers. Either controller may be active in the simplex mode. That is, one controller is actively operating and controlling processors, while the other controller is in a standby mode. In this situation, the synchronization circuit synchronize its clock to itself. When a previously standby controller is made active, the control inputs of the standby controller are manipulated such that, the clock of the standby controller is synchronized to the already active a controller's clock. Once synchronism is achieved, the controllers are said to be operating in a synchronized duplex mode. The synchronization circuit of each controller then continuously checks to insure that the two controller copies are operating synchronously. If a non-synchronous condition is encountered by one of the synchronization circuits, the circuit that detected the lack of synchronization is repeatedly forced to a particular memory location.

Abstract: Common channel interoffice data transfer circuitry is shown for transmitting and receiving both analog and digital CCIS data. This data transfer circuitry is a data terminal equipment control circuit. The terminal equipment control circuit is microprocessor controlled. The terminal equipment control circuit is adaptable to transfer CCIS data to analog interfaces, such as modems. The circuit is also adaptable to transfer CCIS data to and from digital data sources, such as digital trunks or T1 spans. The design of this circuit possesses a high degree of commonality and, therefore, requires a minimal amount of components.

Abstract: A transistorized current amplifier based on a cascode stage feeding into a composite transistorized output stage. The amplifier employs a constant current source, decoupling (isolation) from the power source and a signal limiting network to lower distortion on high signal input conditions. A two-wire device, the amplifier derives signal and power from a telephone line. Surge protection is provided by a signal limiting network and the inclusion of relatively high value resistors in the circuit.

Abstract: A special door is added to the coin receiving mechanism of a pay telephone or other vending machine to discourage the practice of stuffing the mechanism with paper or other foreign matter to trap deposited coins. A slot in the door is normally aligned with the regular slot for coin deposit. If stuffing occurs, the door slides over, misaligning the two slots and preventing deposit of any further coins.

Abstract: A fastener and receptacle arrangement is utilized to perpendicularly connect two pieces of flat stock material together. One piece of flat stock material includes a hole for insertion of the fastener and the other piece includes an opening for mounting a receptacle. The receptacle is secured to that board by a flexible member of the board which engages a recess in the receptacle. The piece of flat stock material with the receptacle secured to it is then perpendicularly secured to the other piece of flat stock material by a fastener which passes through that other piece of flat stock material and fixably engages the receptacle.

Abstract: Method and apparatus is disclosed for identifying faults in a subscriber carrier telephone system utilizing out-of-band pilot signals and comprising pluralities of cables and repeaters that are alternately connected in series between carrier equipment at a central office location and a subscriber station. Equipment at the office location transmits selected numbers of test pulses, having a test frequency that is between the transmitted and received channel and pilot frequencies, to the first cable. The pulses are detected at the first repeater and counted. A microprocessor is responsive to the test pulse count in the repeater for initiating associated tests on the cable and/or repeater, or for retransmitting test pulses on the next cable to the next repeater for causing it it perform designated tests. The results of the tests are sent to the office equipment in the form of reply pulses having a frequency that is below the lowest channel frequency.

Abstract: An output circuit for diode-or connected positive three terminal voltage regulators. A voltage divider develops a voltage signal representative of the output voltage from the positive three terminal regulator. An adjustable precision shunt regulator connected to the voltage divider provides a control signal representative of the variance of the voltage signal from a predetermined threshold signal. The positive three terminal voltage regulator provides a variable output voltage in response to and representative of the control signal.

Abstract: A printed wiring board with zones therein of controlled thermal coefficient of expansion including a first layer of first material, a second layer of second material and a third layer of a third material positioned between the first and the second layers. The third layer includes a first area whereat the material is removed and replaced with a control material possessing a thermal coefficient of expansion different from the first, second and third layers. The third layer and the control material each possess a first side bonded to a first side of the first layer and a second side bonded to a first side of a second layer to form the printed wiring board. Electronic components may be mounted on a second side of the first layer, the second layer, or both the first and second layers and the control material may be varied in composition and thickness to change thermal expansion in the zone above and below the control material.