Abstract: A disconnect circuit for use between two switching systems. An optical coupler monitors open and closed current loop conditions and provides signals representative thereof. Monostable multivibrators are operated in response to these signals to provide timing signals of predetermined durations. A relay circuit is controlled by these timing signals and it operates to disconnect the loop between the switching systems for a predetermined time.

Abstract: A control circuit, for use in a telephone switching system, which monitors, controls and transfers data to and from memory, input-output devices and external circuits. A pair of microprocessors and associated read-only and random-access memories are operated in a master-slave arrangement. A comparison circuit continuously monitors the integrity of the master microprocessor by comparing the signal on its data, address and control leads with those of a slave microprocessor.

Abstract: A test fixture including deflectable test probes employing flexible members attaching a probe head to a probe shaft, the probe head engaging a locating aperture to deflect the probe head to a printed wiring board test point not in alignment with the test probe axis. The test probe head may be of conical shape and include a plurality of ribs spaced along an outer surface thereof to reduce friction. The probe head may include a tip which is rounded to reduce test point damage or optionally pointed to achieve fine test point contacting resolution.

Abstract: A power distribution system that provides supervision and protection. Hall effect devices are used to monitor power from a central power supply to a plurality of power converters. Fuses are connected between the converters and the central power source to protect the converters from catastrophic failure. Hall effect devices also monitor the output of power from the converters. A current controlling inductor is included between the converter outputs and the output power bus in order to restrict reverse current flow from a time that is sufficient to allow a circuit breaker to disconnect a failed converter. The Hall effect devices are connected to a computer which monitors the power in and out of the converters. The computer is thus able to detect a failed converter and disconnects it by operating an associated circuit breaker.

Abstract: A control circuit which monitors the output voltage of multiple power supplies connected to each other in a diode-or arrangement. When one power supply provides a higher voltage than the others the control circuit causes the lower output power supplies to operate in a standby mode. The control circuit includes voltage dividers on both sides of the output diode of the power supplies. These voltage dividers provide indications of the voltage output of their associated power supply and the other power supplies. A voltage comparator monitors the output voltage of its associated power supply and the other diode-or connected power supplies as indicated by the voltage dividers. The voltage comparator to adjust the voltage output of the associated power supply to a level just below the high output power supply, thereby leaving it in a standby mode of operation.

Abstract: A secretarial telephone station for use with a secretarial answering system and a switching system which includes a plurality of subscriber telephone stations each equipped with a buzzer. The secretarial answering system is connected to the subscriber stations and transmits subscriber station busy, idle and ringing status and line identification information to the secretarial station. The secretarial station includes a lamp and switch pair for each associated subscriber station, first and second processing units, and an audible signalling circuit. The first processing unit receives this information according to a link bus protocol for packetized messages. The second processing unit receives this information and causes the lamp associated with each of the subscriber stations to display dark, lit or flashing signals corresponding to the idle, busy and ringing status. The second processing unit also causes the audible signalling circuit to provide a ringing tone whenever a lamp is flashed.

Abstract: A secretarial answering system for use with a switching system which includes a plurality of subscriber telephone stations each equipped with a buzzer, and a secretarial telephone station equipped with an audible signalling circuit and a plurality of lamp and switch pairs. A first processing unit periodically scans line circuits to determine changes in the busy, idle or ringing status of the subscriber stations. A second processing unit converts status and line identification information from parallel to serial format, and transmits it to the secretarial station via a link bus protocol for packetized messages. The secretarial station then provides visual and audible indications of subscriber station status. The secretarial station transmits a switch initiated directed call pickup or a call transfer message to the switching system, and a buzzing requested message to the second processing unit.

Abstract: The present invention consists of a subcircuit which may be employed in integrated circuit technology to provide the necessary drop from a relatively high voltage source and to provide base current for biasing of associated transistorized circuitry. Each subcircuit employs four transistors and one resistor and provides an effective drop from approximately 1.1 volts when it is desired to provide at least 2 microamps of bias circuit. Additional subcircuits of similar configuration can be placed in series with the present circuitry to increase the amount of voltage drop in accordance with the requirements of the associated circuitry.

Abstract: A technique for evaluating keypad conditions while utilizing only a minimum number of ports in a microprocessor involved in control of a telephone instrument. Because of the limited number of ports available and necessity to also evaluate conditions of mode selecting strap switches, the utilization of a reduced number of ports is highly desirable in such an enviroment. Such a reduction becomes an absolute necessity particularly in dealing in those enviroments that include random access memories, read only memories, pulse dialers, integrated circuits and liquid crystal displays. A combination of diode gating, resistive decoupling and time multiplexing techniques are used to match the input/output requirements to the available ports of a specific microprocessor.

Abstract: A laminate switch assembly comprising dual dome switchplates providing improved tactile sensation good balance characteristics and able to maintain a low dynamic resistance throughout its life expectancy. Both tensioned domes are aligned with electrical contact areas part of which is formed on the underside of one dome and the other on a printed circuit board or backplate, which in response to depression are placed in contact with each other to provide a switch closure to a connected or associated electrical device.

Abstract: A low insertion force connection arrangement for establishing a connection between at least two printed wiring boards each of the type including a plurality of printed wiring board terminals. The connection arrangement includes a plurality of connection springs each including an actuator engaging area located centrally on a side of the spring facing the printed wiring boards and between two pivot points. The pivot points are located on a side of the connection spring facing away from the printed wiring boards and between two contacts. The contacts are located at opposite ends of the connection spring, facing, and in alignment with corresponding ones of the printed wiring board terminals.

Abstract: A low insertion force connection arrangement for establishing a connection between at least two printed wiring boards each of the type including at least one printed wiring board terminal. The connection arrangement includes at least one connection spring including an actuator engaging area located centrally on a side of the spring facing the printed wiring boards and between two pivot points. The pivot points are located on a side of the connection spring facing away from the printed wiring boards and between two contacts. The contacts are located at opposite ends of the connection spring facing and in alignment with corresponding ones of the printed wiring board terminals.

Abstract: A low insertion force connection arrangement for establishing a connection between at least two printed wiring boards, each including a plurality of terminals. The connection arrangement includes a plurality of connection springs each having a pivot point facing away from the printed wiring boards and located between two actuator engaging areas. The actuator engaging areas face the printed wiring boards and are located between two contacts. The contacts are located at opposite ends of the connection spring facing and in alignment with a corresponding terminal of the printed wiring boards. A connector body is provided including a plurality of grooves each adapted to receive one of the printed wiring boards and a plurality of spring receiving cavities each enclosing a pair of connection springs.

Abstract: A protective circuit for use in a subscriber's telephone circuit that includes a repertory memory and includes a battery which provides memory retention current. Circuitry permits the battery to be protected by a series current limiting resistor while maintaining sufficient voltage so that the memory maintains its integrity.

Abstract: A control system for use in a condensation heating facility to control the secondary vapor blanket used to prevent loss of primary vapor. The control system includes a pair of secondary vapor sensors which detect a secondary vapor blanket slightly below and alternatively slightly above a design depth. The sensors are connected to control relays which energize a high rate dispensing pump to build the secondary vapor blanket when it is below the low depth and to energize a low rate dispensing pump when the secondary vapor blanket is between the low depth and the high depth. Additional control is arranged to inhibit dispensing of secondary liquid when the secondary vapor blanket is above the high depth or the primary vapor blanket is below its designed depth or finally during a vapor phase heating cycle where the primary and secondary vapor blankets collapse as a function of heating during the cycle.

Abstract: A data entry and display control circuit for use in a telephone having a keypad and a plurality of features and pushbuttons. Each button can be programmed to execute one of the features. The telephone also includes a microprocessor and visual and audible prompting devices. These devices are operated by the microprocessor in response to prolonged operation of a selected pushbutton. Keypad initiated programming signals are then provided to both identify the feature to be assigned to the selected pushbutton and to control display functions. The microprocessor subsequently causes the assigned feature to be performed in response to momentary operation of the selected pushbutton. It also causes the cursor to move in response to the display function control signals.

Abstract: A speech synthesized answering circuit for use with a telepone subscriber station. A microprocessor control circuit monitors a telephone line for detection of a predetermined number of ringing signal bursts. A read-only-memory contains a vocabulary of digitized words. The microprocessor answers the line and forms a telephone answering message by retrieving selected digitized words from the read-only-memory. This message is transferred to a speech processor which converts it to analog format and couples it onto the calling telephone line.

Abstract: A test set which tests coin trunk circuits for both normal and abnormal operations. A pair of light-emitting diodes monitor battery feed and reverse current. A first set of switch contacts simulate coin deposit while a second set of switch contacts connect fault, re-ring, coin deposit and coin return monitoring lamps and circuit paths to the coin trunk circuit.