| Patents for H04M 19 - Current supply arrangements for telephone systems (7,475) |
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| 10/10/1991 | DE4009954A1 Telephone subscriber's appts. signal and power supply circuitry - uses shunt regulator consisting of Zener diodes to separate exchange battery supply and digital signals without attenuation |
| 10/09/1991 | EP0450884A2 A subscriber line interface circuit providing regulated current |
| 10/09/1991 | CN1014292B Apparatus for connecting and disconnecting a ring signal to a called subscriber |
| 10/08/1991 | US5056135 Method of automatic equalized distribution of ring loads for telephone exchange system |
| 09/24/1991 | US5052039 Line interface circuit |
| 09/24/1991 | US5051730 Circuit arrangement for charging rectifiers for DC energy storage devices in telecommunications systems, particularly telephone switching systems |
| 09/18/1991 | EP0446944A2 Feed circuit in exchanger |
| 09/17/1991 | US5050210 Metallic current limiter |
| 09/17/1991 | CA2038376A1 Feed circuit in exchanger |
| 09/17/1991 | CA1289280C Line card with distributed signaling voltages |
| 09/16/1991 | WO1991014333A1 An arrangement for reduced power supply |
| 09/16/1991 | WO1991014330A1 Telephone call detecting circuit and a method of remotely accessing and testing a telephone |
| 09/16/1991 | CA2077747A1 Telephone call detecting circuit and a method of remotely accessing and testing a telephone |
| 09/16/1991 | CA2074479A1 Arrangement for reduced power supply |
| 09/11/1991 | EP0445392A2 Device for transmission of telecommunication signals |
| 09/11/1991 | CN2084691U Protective electric connector for telephone set |
| 09/03/1991 | US5046089 Subscriber line interface circuit with power-down mode |
| 09/03/1991 | CA1288534C Inductance multiplier circuit |
| 08/28/1991 | EP0443583A2 Private branch exchange system |
| 08/22/1991 | WO1991012682A1 Programmable telephone |
| 08/20/1991 | US5042066 Dialer circuit |
| 08/20/1991 | US5042065 Resetting circuit in a key-telephone system |
| 08/14/1991 | CN1053873A Method and apparatus for supplying direct current to telephone line |
| 08/13/1991 | US5040209 Telephone ringing monitoring and control system |
| 08/08/1991 | DE4003160A1 Call disconnection transistor for telephone subscriber loop - includes relay for connecting call generator to loop, and disconnecting call when distant handset is replaced |
| 08/07/1991 | EP0440473A2 Ringing circuit and method for use in a portable telephone set |
| 08/07/1991 | EP0440006A1 A method and arrangement for supplying direct current to a telephone line |
| 08/07/1991 | EP0439641A1 Method and device for forming the line termination of a telephone line |
| 08/07/1991 | CN2082496U Receiving adapter of long-distance supplied source of user carrier wave extession of telephone in city |
| 08/06/1991 | CA1287417C Digital composite tone alerting |
| 08/02/1991 | WO1991011876A1 A method and arrangement for supplying direct current to a telephone line |
| 08/02/1991 | CA2070785A1 Method and arrangement for supplying direct current to a telephone line |
| 07/30/1991 | CA1287197C Battery feed circuit for a telephone system |
| 07/24/1991 | EP0438137A2 Radio telecommunication apparatus |
| 07/17/1991 | CA2032660A1 Line interface circuit |
| 07/10/1991 | EP0435967A1 Device for transmitting information |
| 07/03/1991 | EP0435669A2 Output stage for telephone interface circuit and telephone interface circuit |
| 07/03/1991 | CN1013073B Control system for common line communication of data terminal and telephone |
| 06/27/1991 | DE3942976A1 Power supply for pluggable assemblies at telephone exchange - follows current path from vertical rails of frame to transverse rails with grooves for insulated inserts |
| 06/25/1991 | US5027392 Speaker drive arrangement for loudspeaker telephone |
| 06/25/1991 | US5027391 Call management system |
| 06/18/1991 | US5025467 Cellular telephone ring annunciator |
| 06/18/1991 | CA1285020C Direct current power supply with an emergency supply activated by a polarity reversal |
| 06/05/1991 | EP0430578A2 Telephone interface circuit |
| 06/05/1991 | EP0430137A1 Adaptor arrangement for integrated circuit in a telephone set or terminal remotely powered by a line of analogic type |
| 06/05/1991 | EP0430010A2 Device for transmitting speech signal, signalling and feed over a single pair of conductors in intercommunicating subsets |
| 06/05/1991 | CA2031181A1 Circuit for synthesizing an impedance across the tip and ring leads of a telephone line circuit |
| 06/05/1991 | CA2031180A1 Solid state telephone line circuit |
| 05/28/1991 | US5020102 Semi-floating AC/DC active termination circuit with current sink |
| 05/28/1991 | US5020100 Telephone line loop current regulator |
| 05/23/1991 | DE3938172A1 Exchange battery supplied circuitry for DC=DC converter - uses RC generator in conjunction with switching circuits to provide DC symmetrical voltage for telephone subscriber's appts. |
| 05/08/1991 | EP0425675A1 Ground fault detecting circuit for subscriber lines |
| 05/08/1991 | CN1012607B Subscriber line interface circuit and transformer therefor |
| 05/07/1991 | US5014308 Circuit arrangement for providing power for an IC chip in a telephone subset |
| 05/07/1991 | US5014305 Line interface circuit |
| 04/30/1991 | CA1283742C Subscriber line interface circuit and transformer therefor |
| 04/23/1991 | US5010566 Cordless telephone |
| 04/10/1991 | CN2074959U Universal connecting device for portable telephone power source |
| 04/03/1991 | EP0419973A2 Method for activating an optical display in a communication terminal of a switching exchange |
| 04/03/1991 | EP0419935A2 Subscriber connecting circuit for the connection of a subscriber line to the exchange of a digital time division multiplex communication system |
| 03/27/1991 | CN1050297A Method and apparatus for keyboard adaptation to low power controller in coin operated telephone |
| 03/27/1991 | CN1012250B Telephone set comprising a line voltage stabilizer having a dc supply point |
| 03/26/1991 | US5003578 Power-saving device for a cable-information receiving/transmitting apparatus |
| 03/20/1991 | EP0417977A2 Method and apparatus for keyboard adaptation to a low power controller in a coin operated telephone |
| 03/20/1991 | EP0417788A2 Communication terminal having means for controlling power transfer |
| 03/20/1991 | EP0363362A4 Telephone subset circuit arrangement |
| 03/19/1991 | US5001748 Ringing signal generator |
| 03/16/1991 | WO1991004626A1 Keyboard adaptation to low power controller in a coin telephone |
| 03/13/1991 | EP0416803A2 Apparatus and method for encoding telephone ringing signals |
| 03/06/1991 | EP0415312A1 Power device for telephonic- or telematic terminal |
| 03/05/1991 | US4998273 Telephone line called number recognizer |
| 03/05/1991 | US4998271 Telephone accessory |
| 02/27/1991 | EP0414093A2 Circuit arrangement for charging rectifier for a direct current energy accumulator of a telecommunication installation especially for telecommunications exchanges |
| 02/27/1991 | EP0414051A2 Circuit arrangement for key-controlled switching devices in communication exchanges, especially telephone exchanges |
| 02/27/1991 | CN1049587A Subscriber circuit capable of suppressing in-phase induced noise |
| 02/26/1991 | CA1280834C Telephone line interface circuit |
| 02/19/1991 | US4995111 Ring trip circuit for subscriber telephone |
| 02/19/1991 | US4995110 Method and apparatus for keyboard adaptation to a low power controller in a coin operated telephone |
| 02/19/1991 | US4995075 Apparatus and method for encoding telephone ringing signals |
| 02/19/1991 | US4995072 Self-powered base and remote telephone communication set |
| 02/14/1991 | DE3926102A1 Transmitting digital signal(s) over subscriber line - using supply DC, which is modulated by digital signal in supply DC branch |
| 02/13/1991 | EP0412560A2 Hybrid circuit |
| 02/13/1991 | CN1011653B Battery feed circuit |
| 02/12/1991 | US4993064 Subscriber line interface circuit and transformer therefor northern telecom limited |
| 02/06/1991 | EP0410978A1 Animated data display interleaving. |
| 01/30/1991 | EP0409844A1 Amplifier arrangement and communication line circuit using same. |
| 01/24/1991 | WO1991001069A1 Speaker drive arrangement for loudspeaker telephone |
| 01/23/1991 | EP0409129A1 Telephone set with engaging of the line without lifting the hook |
| 01/23/1991 | EP0235231B1 Subscriber line card arrangement |
| 01/23/1991 | EP0144344B1 Ringing signal generator |
| 01/16/1991 | EP0282567A4 Low voltage and low power detector circuits |
| 01/16/1991 | EP0276296A4 Current-limiting circuit |
| 01/15/1991 | US4985912 Radio telephone device |
| 01/09/1991 | EP0232316B1 Floating battery feed circuit using multifilar transformer |
| 01/08/1991 | US4984267 Telephone |
| 01/08/1991 | US4984266 Subscriber line card arrangement |
| 01/02/1991 | EP0405714A2 Self-powered base and remote telephone communication set |
| 01/02/1991 | CN1011110B Emergency d.c. power supply with emergency state being indicated by polarity reversal |
| 01/01/1991 | US4982426 Telecommunications line interface circuits |
| 01/01/1991 | US4982422 Terminating circuit in a battery feed circuit of an electronic exchange system |