| Patent Number |
Title Of Patent |
Date Issued |
| 4087647 |
Circuit for supplying direct current to telephone station sets |
May 2, 1978 |
| A local battery feed circuit for telephone station sets comprises two half circuit portions substantially symmetric about an imaginary line midway between the TIP and RING telephone lines. Each half circuit includes a current drive amplifier including a pair of up-down emitter follower |
| 4046968 |
Integrable line circuit for use with miniature line transformer |
September 6, 1977 |
| A line transformer circuit in which the DC component of magnetization produced in the tip and ring windings by the battery supplying loop current to the telephone set microphone may be neutralized by an oppositely-poled, serially-connected balancing winding is disclosed. One end of t |
| 4046967 |
Line circuit using miniature line transformer |
September 6, 1977 |
| A line circuit is disclosed employing a transformer having tip and ring windings and a third balancing winding designed to be serially connected in circuit with the tip and ring windings and poled so as to balance out their DC magnetization. The AC components of longitudinal current flow |
| 4032718 |
Four-wire integrable hybrid |
June 28, 1977 |
| A time-sampled port circuit is shown in which the charges impressed by the telephone set on the shunt capacitor of a low-pass filter associated with the port are passively sampled for transmission to the other port circuits, but which capacitor is impulse driven at a repetition rate equa |
| 4028683 |
Memory patching circuit with counter |
June 7, 1977 |
| A read only memory (ROM) patching arrangement is disclosed for providing valid output information whenever ROM word locations containing invalid information are addressed. The disclosed arrangement uses a plurality of small capacity PROMs as a decoder to detect the receipt of each addres |
| 4024349 |
Quasi-resonant transfer conferencing circuit |
May 17, 1977 |
| A conference port for permitting simultaneous voice communication among a plurality of local stations and an external or central office line is shown. The stations may be part of a time division PBX or may be arranged as a time-sampled key telephone system having access to the same line. |
| 4021622 |
Nonlocking key telephone set |
May 3, 1977 |
| A nonlocking key telephone station is arranged to display full line status information when the station is on-hook and for normally illuminating only the key lamp associated with the line in use at the station when the set is off-hook. To permit a user to discern the full status of the l |
| 3993880 |
Resistive battery feed for line circuits |
November 23, 1976 |
| A line circuit, interconnecting a subscriber telephone line and a port circuit, includes shunt battery feed resistors of equal impedance together with resistors in series with the subscriber line and a further resistor connected to a point intermediate one battery feed resistor and the |
| 3967072 |
Time division network connection auditing arrangement |
June 29, 1976 |
| An electronic key telephone system is disclosed in which connections among the station sets and telephone lines are made in a central time division switching network remote from the station sets. Each station set and line is equipped with a port circuit having an individual shift registe |
| 3943296 |
Method and apparatus for reducing noise in pam time division networks |
March 9, 1976 |
| In pulse amplitude modulated time division switching systems, noise and crosstalk often result because the time division switches used to connect individual channels to a common bus are not perfect open circuits when they are in the off-state. The switches in the off-state possess a smal |
