Abstract: A printed wiring board file arranged to mount printed wiring boards in an efficient manner while simultaneously providing for the convection cooling of such boards. The boards include components of varying heights. Each printed wiring board is supported by a connector at one side edge and a printed wiring board guide at the opposite side edge. Each board guide includes two sets of grooves which allow it to be used as a guide for the left or right sides of the boards. The first set of grooves is used when the board guide supports the left side of the printed wiring boards and the second set of grooves is used when the board guide supports the right side of the printed wiring boards. The grooves are formed in the board guide at a vertical spacing less than the minimum permitted vertical spacing for the printed wiring boards. Multiples of the groove spacing are selected to mount printed wiring boards with a minimum or greater than minimum spacing.

Abstract: A power supply circuit for use in a subscriber's telephone that incorporates memory devices for use in repertory dialing, last number recall, and similar functions. This circuit interfaces with the telephone line to provide the data retention supply current needs of volatile static memory devices. It also interfaces with the power supply of the associated logic circuitry to supply the needed operating voltage.

Abstract: A guide for use with a vertically oriented printed wiring board supported on a pair of support beams. The guide is of wire construction including guide fingers alternately formed on both sides of the printed wiring board. Attachment members are formed at either end of the guide and optionally may be formed at one or more locations intermediate the ends. The end positioned attachment members are connected to the support beams and the intermediate attachment members may be connected to an associated aligner rod to maintain the guide in a predetermined alignment.

Abstract: A connector engageable with a plurality of circuit pins including a lock member located within a channel intermediate a plurality of pin receiving apertures. An actuator is provided and operated to deform the lock member in a direction toward side walls of respective ones of the apertures locking the engaged corresponding pins therebetween and preventing disengagement of the connector from the pins.

Abstract: A hold circuit for use with a single line telephone which may or may not be equipped with extension instruments. The circuitry in response to the momentary operation of a manual switch actuates a siliconcontrolled rectifier to place a resistive load across the telephone line thus allowing the subscriber at the basic telephone instrument to go "on hook". Subsequent removal of the basic instrument handset from the hookswitch or an extension phone going "OFF HOOK" will cause the resistive load to be removed. Also included is a hold release circuit which automatically disconnects the hold circuit after a predetermined period of time.

Abstract: An interface circuit for use with a telephone or PABX system or as a device applied to a subscriber's telephone line, that detects ringing voltage signals and either indicates the ringing condition visually or optically couples a detection signal to other annunciator or control devices such as microprocessors. The device conforms to the requirements and limitations for application of a device to the public telephone system. This device does not respond or interfere with voice or data signals nor address signaling.

Abstract: An enclosure for a printed wiring board. The enclosure includes a U-shaped channel member having a ledge in each of its sides. Each ledge has a floor and a wall, and each wall includes at least one projection. A printed wiring board is retained against the ledge floors by means of the projections acting against the printed wiring board. Longitudinal motion of the printed wiring board, in its retained position, is prevented by a tubular projection attached to the U-shaped member extending through an aperture in the printed wiring board. A cover is provided and retained in engagement with the U-shaped member by a plurality of cover projections engaging depressions in a cover receiving ledge formed in the U-shaped member. The enclosure is adapted to be positioned relative to a relay structure by a longitudinal rib attached to the base of the U-shaped member. A fastener extends through the cover and the tubular projection, and engages the relay structure to affix the enclosure to the relay structure.

Abstract: A current regulated pulse dialer circuit including a memory for storing predetermined sequences of telephone numbers, for use in a loop powered pulse dialing telephone. A first current source is connected to an electronic pulse dialer to provide a high impedance across the telephone line during transmission and interpulse pause conditions and a second current source is connected to an electronic pulse dialer to maintain the integrity of information stored in the memory portion of the dialer circuitry.

Abstract: An amplifier combining the properties of high gain, wide band audio response with input signal conditioning, constant current output for use on two wire systems and compound negative feedback for resistance to oscillation in acoustic feedback environments. The direct coupled amplifier combines a modified cascode stage with a composite connected transistor output stage. It is intended primarily for use in two wire communication of voice transmission such as in telephone handsets or telephone instruments.

Abstract: A monitor circuit which discriminates between valid and invalid (bouncing) changes in state of monitored sense points. A microprocessor periodically scans a plurality of sense points, logically determines the validity of each sense point during each scan and stores data representing the validity of these sense points in a memory.

Abstract: A hookswitch mechanism for use in a telephone instrument utilizing a compound form cantilever spring fastened to a printed wiring card with circuit connections made to the printed wiring card. A contact engaging portion on the cantilever spring wipes across a contact located on the printed wiring card before disengaging the contact to insure a clean contact surface regardless of surrounding atmospheric conditions.

Abstract: A hold circuit for use with a single line telephone operable over long or short telephone loops. The included circuit during response to the momentary operation of a manual switch actuates a silicon controlled rectifier to place a resistive load across the telephone line thus allowing the subscriber at the telephone instrument to go "on-hook". Subsequent removal of the basic instrument handset from the hook-switch, or of a related extension telephone going "off-hook", will cause the resistive load to be removed.

Abstract: A test circuit which detects Hall effect device operate and release time failures. This circuit includes a magnetic field circuit, a comparison circuit, a storage circuit and a visual indication circuit. The magnetic field circuit causes a Hall effect device under test to periodically switch states. The operate and release times of such switching is compared to predetermined thresholds by the comparison circuit. Switching times within the allowable thresholds cause the storage circuit to operate the visual indication circuit.

Abstract: A circuit which monitors air flow by comparing the speed of a fan to a predetermined frequency. A Hall effect device detects magnetic pulses representative of the fan speed and provides a corresponding electrical signal. This signal is compared with a predetermined threshold frequency by a retriggerable monostable multivibrator. A digital delay circuit isolates pace conditions and a relay circuit provides an indication of the fan speed status.

Abstract: A frequency disturbance minimization circuit for use in a phase locked loop circuit. A pulse generator eliminates random phase shift, which occurs after a reference clock outage, by synchronizing counted down derivatives of the local and reference clock circuits. A window circuit provides a signal representative of the difference in phase between these local and reference clock circuits. A counter accumulates these phase difference window signals for periodic interrogation by a microprocessor which causes a voltage controlled oscillator to adjust its frequency in the direction necessary to eliminate this phase difference.

Abstract: A signal transmission system which allows digital signals to be transmitted over twisted pair transmission lines. Master and slave transmission circuits are located at the switching system and terminal ends, respectively, of the transmission line. Both circuits include transmit and receive circuitry. The transmit circuitry includes a summing circuit connected to a constant current generator and the receive circuit includes an adaptive equalization/automatic gain control circuit connected between a differential amplifier and a slicer circuit.

Abstract: A low insertion force connection arrangement for establishing a connection between at least two printed wiring boards, each board of the type including at least one printed wiring board terminal. The connection arrangement includes at least one connection spring 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 a corresponding terminal of each of the printed wiring boards. A connector body is provided including a plurality of grooves each adapted to receive and retain one of the printed wiring boards in alignment with the other boards, and a plurality of spring receiving cavities, each cavity enclosing a pair of connection springs and including a molded-in fulcrum opposite each spring's pivot point.

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 boards terminals.