| Patents for H04M 19 - Current supply arrangements for telephone systems (7,475) |
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| 07/07/1987 | CA1223994A1 Electric source circuit for telephone sets |
| 07/01/1987 | EP0227186A2 Circuit arrangement for the evaluation of the output signals of current detectors in telecommunication systems |
| 06/30/1987 | US4677669 Battery feed circuit for a pair of subscriber lines |
| 06/30/1987 | US4677664 Method and apparatus for an improved ring trip detection telephone circuit |
| 06/23/1987 | US4675653 Keyboard arrangements |
| 06/16/1987 | US4674119 Wide-band high voltage amplifier for telephone exchange subscriber line interface utilizing low voltage control circuitry |
| 06/10/1987 | EP0225231A1 Connection and powering device for a telephone transceiver |
| 06/10/1987 | EP0225069A2 Telephone power supply |
| 06/04/1987 | DE3542407A1 Circuit arrangement for transmitting communications signals |
| 06/03/1987 | EP0224212A2 Dial tone detection arrangement with a detection notification feature |
| 05/27/1987 | DE3541547A1 Ringing voltage evaluation |
| 05/27/1987 | CN86107804A Solid state trunk circuit |
| 05/26/1987 | CA1222333A1 Current supply circuit |
| 05/21/1987 | DE3535868C1 Call signal recognition circuitry for telephone subscriber's appts. - has current sensor between rectifier and diode supplying detector sensing frequency |
| 05/13/1987 | EP0221519A2 Ringing application circuit |
| 05/12/1987 | US4665547 Limiting amplifier for common mode feedback in telephone line feed circuits |
| 05/07/1987 | DE3538698A1 Telecontrol system |
| 05/05/1987 | US4663759 Ring back tone transmission system |
| 05/05/1987 | CA1221482A1 Telephone instruments |
| 04/28/1987 | US4661978 Subscriber line interface circuit having an impedence synthesizer |
| 04/23/1987 | DE3537187A1 Voice transformer |
| 04/14/1987 | US4658419 Telephone ringer circuit |
| 04/08/1987 | EP0217369A2 Power transmission arrangement for telecommunications systems |
| 04/08/1987 | EP0217130A2 Circuit arrangement for an electronic interface circuit |
| 04/07/1987 | US4656661 Switched capacitor coupled line receiver circuit |
| 04/07/1987 | US4656659 Programmable ring signal generator |
| 04/02/1987 | DE3533762A1 Circuit arrangement for connecting a subscriber terminal to a subscriber connection line |
| 03/31/1987 | US4654869 Information collecting and forwarding apparatus |
| 03/26/1987 | DE3543798A1 Circuit arrangement for the line feed of ancillary devices of a telephone set |
| 03/26/1987 | DE3543797A1 Circuit arrangement for the line feed of ancillary devices of a telephone set |
| 03/25/1987 | EP0215677A2 Subscriber line interface circuit having means for combining DC and AC feedback signals |
| 03/24/1987 | US4653091 Supply for a subscriber control system |
| 03/24/1987 | US4653088 Telephone circuitry with power backup |
| 03/24/1987 | US4653046 Single channel subscriber carrier system |
| 03/24/1987 | US4652701 Ringing application circuit |
| 03/18/1987 | EP0214915A2 Information collecting and forwarding apparatus and method of operating such an apparatus |
| 03/18/1987 | CN86105137A Connector circuit for user's wire |
| 03/12/1987 | WO1987001547A1 Subscriber line card arrangement |
| 03/11/1987 | EP0213342A2 Programmable ring signal generator |
| 03/05/1987 | DE3531556A1 Circuit arrangement for a telephone set with a digital clock |
| 03/05/1987 | DE3530064A1 Circuit arrangement for connecting telecommunications devices, in particular telephone devices to a telecommunications network |
| 03/04/1987 | EP0212632A2 Subscriber line interface circuit |
| 03/04/1987 | CN86204038U Magnet telephone with emergency function |
| 03/03/1987 | US4648019 High efficiency ringing generator |
| 03/03/1987 | US4647787 Backup battery power supply for microprocessor based telephones |
| 02/24/1987 | US4646347 Ringing signal reformatting circuit |
| 02/24/1987 | US4645881 DC level trip detector |
| 02/19/1987 | DE3529371A1 Circuit arrangement for a telephone subscriber station |
| 02/19/1987 | DE3528281A1 Circuit arrangement for transmitting communications signals |
| 02/17/1987 | US4644579 Shunt regulator for hands-free telephone |
| 02/17/1987 | US4644476 Dialing tone generation |
| 02/17/1987 | US4644106 Apparatus for timely controlling the sound characteristic of a signaling means of a voice communication device |
| 02/12/1987 | WO1987001004A1 Method and apparatus for providing a ground reference for telephone customer special circuits powered from a floating battery feed |
| 02/12/1987 | WO1987000997A1 Floating battery feed circuit using multifilar transformer |
| 02/12/1987 | DE3527262A1 Circuit arrangement for the feed voltage supply of a telephone station |
| 02/10/1987 | CA1217887A Single power supply battery feed circuit |
| 02/10/1987 | CA1217827A Current characteristic shaper |
| 01/31/1987 | CN85102113A Audio frequency transmission circuit formed by line-voltage stabilizer type transmitting amplifier |
| 01/31/1987 | CN85101395A Wideband high voltage amplifier for telephone exchange subscriber line interface utilizing low voltage control circuitry |
| 01/29/1987 | WO1987000717A1 A telephone line switch |
| 01/28/1987 | EP0209716A2 Circuit for the suppression of perturbing signals on the reception branch line of a subscriber line circuit realized by electronic components without the use of a voice transformer |
| 01/27/1987 | US4639551 Regulated power supply circuit particularly for telephone set |
| 01/21/1987 | EP0208875A1 Circuit for the separation of the direct and alternating current portions of a signal mixture |
| 01/20/1987 | CA1216906A1 Line powered modem |
| 01/14/1987 | CN85103519A Pulse/direct current multiplexing circuit in key telephone system |
| 01/13/1987 | US4636588 Electric source circuit for telephone sets |
| 01/13/1987 | US4636587 Electronic switch for digital telephone |
| 01/13/1987 | US4636585 Telephone installations |
| 01/08/1987 | DE3523107A1 Digital telephone subscriber station |
| 01/07/1987 | EP0107074B1 Process for the suppression of quantification noise superposed on a sinusoidal audible tone at the transmission in a digital telecommunication exchange |
| 12/30/1986 | US4633038 Supply circuit for a variable load, particularly for a line circuit in telephone systems |
| 12/24/1986 | CN85103135A Circuit of telephone bell with electronic music |
| 12/23/1986 | US4631366 Battery feed circuit for subscriber line |
| 12/23/1986 | US4631361 Programmable ring generator |
| 12/23/1986 | US4631360 Apparatus for the current supply of a subscriber set from an exchange |
| 12/23/1986 | US4631359 Arrangement for supplying current to a subscriber telephone set |
| 12/16/1986 | CA1215428A1 Floating battery feed circuit |
| 12/10/1986 | EP0203938A1 Interswitch line circuit |
| 12/10/1986 | CN85109245A Telephone line status circuit |
| 12/09/1986 | US4628249 Power supply having a predetermined value of input impedance |
| 12/03/1986 | EP0203394A2 Electronic music/voice ringer circuit for telephone |
| 12/03/1986 | EP0112840B1 Apparatus for controlling the application of telephone line power in a telephone set |
| 12/02/1986 | US4626626 Interface for a telephone set |
| 11/26/1986 | CN85104082A Battery supply circuit for the consumers' line |
| 11/20/1986 | EP0201635A1 Telecommunication line circuit |
| 11/18/1986 | US4623760 Signaling protocol interface channel unit |
| 11/12/1986 | CA1213992A Method and circuitry for encoding telephone ringing signals |
| 11/11/1986 | US4622442 Electronic hybrid having synthesized impedance circuitry |
| 11/11/1986 | US4622441 Two-wire/four wire communication interface with noise rejection |
| 11/11/1986 | US4622439 Detection of ground or loop start configuration in telephone loop signalling circuit |
| 11/05/1986 | EP0199865A1 Active impedance transformer-assisted line feed circuit with filtering function of supervision signals |
| 11/04/1986 | US4621170 Means of transmitting signals along a line while also providing a direct voltage source |
| 10/29/1986 | CN86102953A Key telephone system |
| 10/22/1986 | EP0198360A2 Circuit for the remote powering of subscriber connecting devices in telephone exchanges |
| 10/15/1986 | EP0197433A2 Switching system having a tone trunk and method for generating digital codes therein |
| 10/14/1986 | US4617426 Method for current supply to a subscriber telephone from a telephone exchange |
| 10/08/1986 | EP0134229B1 Borsht/slic auto balancing technique |
| 09/30/1986 | US4614840 Telecommunication line circuit and associated polarity reversal circuit |
| 09/23/1986 | CA1211875A1 Tone generator |
| 09/17/1986 | EP0104220B1 Supply circuit included in a dc-magnetized hybrid transformer |