| Patents for H04M 19 - Current supply arrangements for telephone systems (7,475) |
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| 05/31/1988 | US4748664 Telephone power supply |
| 05/31/1988 | US4748659 Calling signal transmission apparatus |
| 05/31/1988 | US4748652 Circuit for detecting abnormality in feeder |
| 05/18/1988 | EP0267808A2 Telephone circuit for supplying ringing signals to a subscriber telephone line and for detecting unhooking |
| 04/28/1988 | DE3635514A1 Circuit arrangement for controlling the feed current for a telecommunications terminal |
| 04/27/1988 | EP0264910A2 An integrated ringing circuit and a ring trip circuit for the same |
| 04/26/1988 | US4741031 For use in a hazardous environment |
| 04/13/1988 | EP0263416A1 Electronic speech circuit |
| 04/12/1988 | US4737989 Ringing circuit |
| 04/12/1988 | US4737988 Current supply circuit |
| 04/12/1988 | US4737987 Circuit for evaluating call signals in a telecommunication system |
| 04/12/1988 | US4737732 Low voltage operational amplifier having a substantially full range output voltage |
| 04/12/1988 | CA1235241A1 Resistive line circuit |
| 04/12/1988 | CA1235240A1 Electronic battery feed circuit for telephone systems |
| 04/05/1988 | US4736415 For supplying DC power to a communication station |
| 04/05/1988 | US4736412 Method of and circuit arrangement for evaluating the output signals of current flow detectors in telecommunication facilities |
| 04/05/1988 | CA1234939A1 Power amplifier |
| 03/30/1988 | EP0161253B1 Interface channel unit |
| 03/29/1988 | US4734937 Telephone installation |
| 03/29/1988 | US4734936 Ringing signal sending-out circuit |
| 03/29/1988 | US4734933 Telephone line status circuit |
| 03/29/1988 | CA1234646A1 Wideband high voltage amplifier for telephone exchange subscriber line interface utilizing low voltage control circuitry |
| 03/29/1988 | CA1234598A1 Off-line switching mode power supply |
| 03/24/1988 | WO1988002204A1 Low voltage and low power detector circuits |
| 03/24/1988 | WO1988002121A1 Quad exchange power controller |
| 03/17/1988 | DE3631438A1 Circuit arrangement to compensate for direct-current magnetomotive forces in transformers |
| 03/15/1988 | US4731831 Telephone instrument |
| 03/15/1988 | US4731830 Nonsaturating interface supply |
| 03/15/1988 | US4731828 Ring trip detection in telecommunications exchanges |
| 03/15/1988 | US4731827 Interswitch line circuit |
| 03/09/1988 | EP0259247A1 Circuitry for a telephone set |
| 03/08/1988 | CA1233924A1 Telephone line status circuit |
| 03/01/1988 | CA1233582A1 Power supply for telephone equipment memory devices |
| 03/01/1988 | CA1233581A1 Self adjusting bias power supply for line powered telephones |
| 03/01/1988 | CA1233580A1 Battery feed circuit for subscriber line |
| 02/24/1988 | EP0256291A2 Circuit for the separation of the direct and alternating current portions of a signal mixture |
| 02/23/1988 | US4727574 Subscriber line interface circuit with improved d.c. balance |
| 02/23/1988 | US4727572 Telephone annunciator with low battery indication |
| 02/23/1988 | CA1233283A1 Subscriber line interface circuit with longitudinal current suppression |
| 02/16/1988 | US4726060 Line circuit for driving a ringer and a service indicating lamp in a telephone set |
| 02/16/1988 | CA1232988A1 Subscriber line interface circuit with improved d.c. balance |
| 02/11/1988 | WO1988001109A1 Reset and synchronization interface circuit |
| 02/11/1988 | WO1988001075A1 Current-limiting circuit |
| 02/03/1988 | EP0255374A2 Telephone circuit for supplying ringing signals to a subscriber telephone line and for detecting the unhooked condition during ringing |
| 02/02/1988 | US4723280 Constant current line circuit |
| 02/02/1988 | US4723275 Circuit arrangement for generating an acoustic ringing signal in a subscriber telephone set |
| 01/28/1988 | DE3722583A1 Teilnehmerleitung-schnittstellenschaltung Subscriber line interface circuit |
| 01/14/1988 | WO1988000420A1 Method and apparatus for feeding power to a telephone line |
| 01/13/1988 | EP0252557A1 DC-supply arrangement for a telecommunication line |
| 01/13/1988 | EP0252259A2 Device for powering an apparatus situated at the subscriber side in a telephone system |
| 01/12/1988 | CA1231480A1 Constant current line circuit |
| 01/07/1988 | EP0251747A1 Power recovery and line driving circuit |
| 01/07/1988 | EP0251038A1 Device for disconnecting the wires of a subscriber connection line from the powering circuit |
| 01/06/1988 | CN85108230B Ringing signal sending circuit |
| 01/05/1988 | US4718084 Overload protection circuit for a telephone subscriber line feed circuit |
| 12/30/1987 | CN87104233A Telephone set comprising a line voltage stabilizer having a dc supply point |
| 12/23/1987 | EP0250030A1 Telephone set comprising a line voltage stabilizer having a DC supply point |
| 12/23/1987 | DE3620857A1 Cordless telephone |
| 12/09/1987 | EP0248177A2 Remote supply device |
| 12/08/1987 | US4712233 Monolithic telephone subscriber line interface circuit |
| 12/03/1987 | DE3618500A1 Circuit arrangement for polarity-reversal protection |
| 11/25/1987 | EP0246546A1 Telephone subscriber circuit |
| 11/24/1987 | US4709388 Subscriber telephone line interface circuit with reduced power stand-by mode |
| 11/24/1987 | CA1229689A1 Circuit for maintaining the dc voltage on an electrically isolated telecommunication line at a reference level |
| 11/19/1987 | WO1987007104A1 Apparatus in a telecommunication system for supplying power to a telephone set |
| 11/19/1987 | DE3616585A1 Telephone set |
| 11/19/1987 | DE3616488A1 Subscriber circuit for a domestic telephone system |
| 11/17/1987 | US4707855 Personalized telephone signaling circuitry and device, and methods of constructing and utilizing same |
| 11/10/1987 | US4706281 Dynamic impedance element for a battery feed circuit |
| 10/28/1987 | EP0242541A2 Circuit arrangement for a pulse generation telephone apparatus |
| 10/27/1987 | US4703500 Power amplifier |
| 10/27/1987 | CA1228643A1 Analog process controller with digital monitor |
| 10/20/1987 | US4701947 Circuit arrangement for suppressing interference signals on the receiving arm of a telephone subscriber line circuit |
| 10/15/1987 | DE3612823A1 Circuit arrangement for feeding electrically erasable and programmable non-volatile memories in telephone terminals |
| 10/01/1987 | DE3610507A1 Circuit for feeding a telephone device from the exchange line |
| 10/01/1987 | DE3610506A1 Circuit for supplying power to a telephone device from the exchange line |
| 09/30/1987 | EP0137783B1 Floating battery feed circuit |
| 09/29/1987 | CA1227587A1 Sine wave ring generator |
| 09/24/1987 | DE3609855A1 Controller for acoustic caller device in telephone - has timer for disconnecting ringer for set period terminated by automatic reconnection |
| 09/23/1987 | EP0237656A2 Telecommunication line circuit and amplifier circuit used therein |
| 09/23/1987 | CN87101944A 振铃电路 Ringing circuit |
| 09/16/1987 | EP0237303A1 Ringing circuit |
| 09/15/1987 | CA1226983A1 Audio transmission circuit comprising a transmit amplifier in the form of a line voltage stabiliser |
| 09/09/1987 | EP0235622A2 Circuit arrangement for the powering of a telephone equipment comprising a main telephone set and a plurality of extension telephone sets |
| 09/02/1987 | EP0233892A1 A telephone line switch. |
| 08/12/1987 | EP0231466A1 Device for the indication of looping in the ringing phase |
| 08/11/1987 | US4686700 Telephone off-hook detector circuit |
| 08/04/1987 | US4685130 Subscriber line circuit having an improved loop current supply circuit |
| 08/04/1987 | US4685129 Power transmission arrangement for telecommunications systems |
| 07/28/1987 | US4683351 Impedance maintenance circuit for telephone interface |
| 07/28/1987 | CA1224894A1 Subscriber line interface circuit having an impedance synthesizer |
| 07/28/1987 | CA1224893A1 Dialing tone generation |
| 07/21/1987 | US4682355 Electronic feeding bridge for a space division switching network |
| 07/16/1987 | DE3600864A1 Circuit arrangement with means for setting the correct polarity of a telephone connection line |
| 07/15/1987 | EP0228567A1 Circuitry for continually feeding a current to the subscriber line of a digital time division multiplex communication network |
| 07/14/1987 | US4680758 Switching system having tone trunk |
| 07/14/1987 | CA1224293A1 Dtmf-telephone set with multiple use of the logic of the digital tone generator |
| 07/07/1987 | US4679232 Method and apparatus for providing a ground reference for telephone customer special circuits powered from a floating battery feed |
| 07/07/1987 | US4679229 Ringing detection circuit |
| 07/07/1987 | US4679132 For supplying power from a source |