Patents
Sitemap › H04 - Electric communication technique › H04M - Telephonic communication › H04M 19 - Current supply arrangements for telephone systems
Patents for H04M 19 - Current supply arrangements for telephone systems (7,475)
01/1990
01/23/1990US4896351 Apparatus for separating dc current and ac current components of a composite signal
01/23/1990US4896093 Electronic inductor
01/18/1990DE3922806A1 Telefonapparat mit tonerzeugungsvorrichtung Telephone with tone generating device
01/18/1990DE3823597A1 Circuit arrangement for DC voltage supply of memory modules in a line-powered telephone station
01/17/1990EP0351009A2 Telephone line loop current regulator
01/17/1990CN1038907A Method and apparatus for electronic payphone open switch interval management
01/11/1990WO1990000333A1 Method and apparatus for electronic payphone open switch interval management
01/11/1990DE3823236A1 Method for a program-controlled telephone switching system with a central controller which performs all switching functions
01/10/1990CN1006434B Pulse/direct current multiplexing circuit in key telephone system
01/03/1990EP0349302A2 Method and apparatus for electronic payphone open switch interval management
01/03/1990CN1006353B Ringing circuit
12/1989
12/28/1989DE3821270A1 Method for charging buffer capacitors in a telephone terminal
12/27/1989CN1006272B Wideband high voltage amplifier for telephone exchange subscriber line interface utilizing low voltage control circuitry
12/21/1989DE3820624A1 Device for supplying power to equipment
12/20/1989EP0347343A1 AC/DC converter and its use in a telephone apparatus
12/20/1989EP0346874A2 Telephone circuit using DC blocked transformer and negative impedance technique
12/20/1989CN1038194A Low power control apparatus for coin operated telephone
11/1989
11/30/1989WO1989011766A1 Low power control apparatus for a coin operated telephone
11/29/1989EP0343966A2 Low power control apparatus for a coin operated telephone
11/29/1989CN1005950B Volume control circuit for use in portable telephone or the like
11/28/1989US4884294 Portable cordless telephone set for outputting various discriminiation sounds with simple circuit construction
11/23/1989EP0342507A2 Circuit for feeding equipments in telecommunication exchanges, especially in phone exchanges
11/21/1989US4882506 Low voltage and low power detector circuits
11/02/1989WO1989010610A1 Animated data display interleaving
11/02/1989EP0339351A2 Connection device for alternative call current at subscriber connection lines
11/02/1989EP0339201A2 Feeding circuit for terminals by a connection line with digital information transmission
10/1989
10/25/1989CN1036651A Digital composite tone alerting
10/17/1989US4875232 Telephone power distribution and isolation system
10/12/1989DE3809576A1 Switching device for providing polarity in telecommunications devices
10/10/1989US4873502 Negative immittance converter
10/04/1989CN2045560U Power supply system for program controlled telephone exchanger
10/03/1989US4872199 Battery-feed circuit for exchange
09/1989
09/28/1989DE3809674A1 Circuit arrangement for controlling calling signals for telecommunications devices
09/28/1989DE3809012A1 Method for controlling volume in a telephone station
09/26/1989CA1260170A1 Subscriber line interface circuit
09/12/1989US4866768 Station line interface circuit for a telecommunication network
09/12/1989US4866767 Subscriber line interface circuit
09/12/1989US4866766 Telephone device having customized ring capability
09/12/1989US4866757 Combined telephone and power distribution system
09/12/1989US4866587 Electronic ringing signal generator
09/12/1989CA1259387A1 Power transmission arrangement for telecommunications systems
09/06/1989EP0331371A2 Digital composite tone alerting
09/06/1989EP0330961A1 Telephone line interface circuit
09/06/1989CN1035405A Line interface circuit
09/05/1989US4864609 Telephone line interface circuit
08/1989
08/30/1989EP0330274A1 DC supply for an S-bus in ASDN
08/29/1989US4862495 Telecommunications subscriber line interface circuit and party identification facility
08/29/1989US4862309 Protection circuit for battery feed circuit
08/29/1989CA1258930A1 Active impedance line feed circuit
08/22/1989US4860346 Telephone system and method operated from central office loop current
08/22/1989US4860345 Telephone system and method operated from central office loop current
08/22/1989US4860287 Network having a synchronizer for synchronization between a primary and a remote station
08/17/1989DE3803710A1 Schaltungsanordnung fuer fernsprechendgeraete Circuit arrangement for telephone terminals
08/16/1989EP0328462A1 Integrated circuit and remotely powered telephone set using it
08/10/1989DE3804251C1 Generation of control voltages for a switching controller component
08/08/1989US4856059 Semiconductor subscriber line interface circuit with enhanced survivability
08/08/1989US4856057 Apparatus in a loudspeaking telephone set for supplying power to an amplifier connected to the loudspeaker
08/08/1989US4856056 Apparatus for timely controlling the sound characteristic of a signaling means of a voice communication device
08/08/1989US4856055 Controllable telephone annunciator
08/03/1989DE3802329A1 Circuit arrangement for the interface to connect a telephone set to a subscriber connection line
08/03/1989DE3801875A1 Circuit arrangement for power supply devices in telecommunications systems, in particular telephone switching systems
08/03/1989DE3801841A1 Circuit arrangement for dial keypads in communications terminals
08/02/1989EP0179812B1 Circuit for maintaining the dc voltage on an electrically isolated telecommunication line at a reference level
08/01/1989US4853959 Method and apparatus for feeding power to a telephone line such that for restricted battery voltage there is enabled the transmission of an undistorted speech signal
07/1989
07/27/1989DE3804250C1 Circuit arrangement for a current limiter
07/27/1989DE3802205A1 Device for setting communications standby in telephone sets
07/25/1989US4852162 Subscriber line interface circuit
07/18/1989US4849850 Circuit for protecting electronic devices against overload
07/18/1989CA1257722A1 Subscriber line interface circuit having means for combining dc and ac feedback signals
07/12/1989EP0323516A1 Ring trip circuit for subscriber telephone.
07/11/1989US4847899 Power circuit for telephone accessory devices
07/11/1989US4847898 Speech circuit configuration
07/11/1989US4847896 Monolithically integratable telephone circuit for supplying ringing signals to a subscriber's telephone line and for detecting an off the hook condition during ringing
07/05/1989EP0323223A2 Telephone interface circuit
07/04/1989CA1257027A1 Compensation circuit for use with an integrating amplifier
07/04/1989CA1256941A1 High efficiency ringing generator
06/1989
06/29/1989DE3743055A1 Circuit arrangement for feeding supplementary circuits of a telephone set
06/27/1989CA1256611A1 Method of and circuit arrangement for evaluating the output signals of current flow detectors in telecommunication facilities
06/21/1989EP0321049A2 Telephone terminal with a signal processor
06/21/1989EP0233892A4 A telephone line switch.
06/20/1989US4841565 Monolithically integratable telephone circuit for feeding a subscriber's telephone line
06/20/1989US4841564 DC-supply arrangement for a telecommunication line
06/06/1989US4837818 Telecommunication line circuit
06/06/1989CA1255408A1 Subscriber line circuit having an improved loop current supply circuit
05/1989
05/30/1989CA1255026A1 Dc control circuit
05/23/1989US4833709 Remote telephone signaling circuitry and device
05/11/1989DE3740026A1 Zusatzeinrichtung zu einem an einer telefonleitung angeschlossenen telefon Accessory to a phone connected to a phone line
05/09/1989US4829567 Line interface circuit
05/03/1989EP0314237A1 Negative immittance converter
05/03/1989EP0313776A2 Charging unit for cordless telephone
05/02/1989US4827505 Subscriber line interface circuit
05/02/1989US4827503 Integrated ringing circuit and a ring trip circuit for the same
04/1989
04/26/1989CN1032610A Apparatus for connecting and disconnecting a ringing signal to a called subscriber
04/25/1989US4825349 Emergency D.C. power supply with the emergency state being indicated by polarity reversal
04/20/1989WO1989003625A1 Apparatus for connecting and disconnecting a ringing signal to a called subscriber
04/18/1989CA1252927A1 Ringing application circuit
04/12/1989EP0311580A1 Apparatus for connecting and disconnecting a ringing signal to a called subscriber
04/11/1989US4821315 Electronic contacts and associated devices
04/11/1989US4821314 Message and ringing signaling device for a telephone installation
04/11/1989CA1252585A1 Method and apparatus for providing a ground reference for telephone customer special circuits powered from a floating battery feed
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