Patents
Patents for H04M 19 - Current supply arrangements for telephone systems (7,475)
04/1994
04/27/1994EP0593556A1 Telephone marketing system
04/26/1994US5307407 20 Hz ring generator using high frequency PWM control
04/26/1994US5307406 ISDN power source detection circuit
04/20/1994EP0592493A1 Personal communication system providing supplemental information mode
04/19/1994US5304917 Compact low noise low power dual mode battery charging circuit
04/19/1994CA2006554C Electrical apparatus power switch and remote control terminal apparatus equipped with said switch
04/12/1994US5303284 Ringing circuit for use in portable telephone set
04/06/1994EP0590242A1 Circuit arrangement to feed digital terminals with simulated-inductance circuits
04/05/1994CA2004690C Current limit circuit for ringing amplifier
03/1994
03/24/1994DE4231389A1 Variable control current supply circuit contg. two current paths - produces subsidiary control signal for variation of current in one path to steepen slopes of output current waveform.
03/24/1994DE4222401A1 Telephone call signal processing arrangement - uses call tone recognition circuit which either accepts or rejects a clock signal depending on position in signal band.
03/23/1994EP0587966A1 Circuit arrangment for priority-feeding of devices from the loop current
03/23/1994EP0587575A1 Telephone line interface circuit with voltage switching
03/17/1994WO1994006254A1 Cordless telephone system with different ringing patterns
03/17/1994WO1994006215A1 Communication device connected to an interface circuit employing opto-isolators
03/16/1994EP0586906A2 Mobile communications equipment
03/15/1994US5295185 Ringing signal generation circuit with protection against overvoltage
03/15/1994CA2025140C Communication terminal having means for controlling power transfer
03/15/1994CA2001472C Data circuit-terminating equipment with power source device attached thereto
03/10/1994DE4241306C1 Telephone subscriber circuit with back-up voltage supply - uses capacitor charged automatically from exchange line under control of normal telephone function
03/08/1994US5293420 Ring trip circuit
03/08/1994CA2005260C Telephone ringing detector
03/02/1994CN1083296A Low power emergency telephone mode
02/1994
02/28/1994CA2077052A1 Incoming call manager
02/22/1994US5289537 On-hook transmission circuit in cable line
02/22/1994US5289359 DC-DC power converter including sensing means for providing an output when the reserve power of the converter falls below a predetermined amount for a given input voltage
02/17/1994WO1994003990A1 Isolation interface apparatus
02/17/1994DE4237395C1 Verfahren zum Programmieren einer Basisstation mit Hilfe eines Mobilteils A method for programming a base station with the aid of a handset
02/16/1994EP0233892B1 A telephone line switch
02/09/1994EP0582439A1 Subscriber line interface circuit with impedance synthesis
02/09/1994CN1081798A A communications device
02/07/1994CA2097354A1 Battery feed circuit
01/1994
01/26/1994EP0580340A1 Telephone apparatus and method
01/26/1994EP0580249A2 Method and device for the matching of the impedances of the subscriber termination and of the subscriber access to the characteristic impedance of the subscriber telephone line
01/20/1994DE4222977A1 Telephone subscriber unit with telephone terminal - allows subscriber to program and store individual acoustic signals such as music or speech to be played back when triggered.
01/19/1994EP0579557A1 Portable facsimile apparatus
01/18/1994US5280523 Telephone line message waiting and ring indicator
01/13/1994DE4236811C1 Verfahren zum Laden von Akkumulatoren in schnurlosen Kommunikationsendeinrichtungen und Anordnung zur Durchführung des Verfahrens Method for charging batteries in cordless communication terminal equipment and arrangement for carrying out the method
01/05/1994EP0577474A1 Ringing circuit for telephone set
01/05/1994EP0577057A2 Line termination of a telephone line
12/1993
12/29/1993EP0576209A1 Remote charging cradle for cordless telephone handset
12/28/1993US5274704 Transformer telephone line interface circuit
12/28/1993US5274703 Automatic loss control circuit
12/28/1993US5274702 For a two-wire telecommunications line
12/28/1993US5274701 Telephone alerter
12/16/1993DE4218845A1 Ringing tone voltage generator including PWM - is entirely integrated except for transformer whose sec. winding feeds amplitude-regulating operational amplifier and discharge transistor
12/14/1993US5271059 Method and configuration for forming a line termination of a telephone line
12/09/1993WO1993025037A1 Low loss telephone circuit
12/08/1993EP0572872A2 Circuit arrangement for reducing power consumption of a telecommunication terminal
12/08/1993CN1023051C Communication central exchange
12/02/1993DE4217297A1 Wide band communication system optical network current supply - supplies electric energy for opto-electric conversion and to devices at subscriber end individually from subscriber
11/1993
11/24/1993EP0570425A1 An emergency call unit
11/18/1993EP0569582A1 Telephone ringing signal generator
11/09/1993US5260996 Current limited electronic ringing generator
11/09/1993US5260995 Electric power circuit for telephone set use
11/09/1993US5260992 Key telephone system with reduction of delay of ring tone generation at telephone set
11/09/1993US5260937 Power conserving technique for a communications terminal time slot interchanger
11/03/1993CN1078080A Hybrid fiber in the loop telephony system
11/02/1993US5258713 Impedance generator for a telephone line interface circuit
11/02/1993CA2020870C Radio telecommunication apparatus
10/1993
10/28/1993WO1993021724A1 Subscriber line interface circuit with voltage controlled loop current
10/28/1993WO1993021723A1 Impedance synthesizer for a subscriber line interface circuit
10/28/1993WO1993021722A1 Wideband telephone line interface circuit
10/21/1993DE4214125C1 Signal level and frequency monitoring for telephone call tone circuit - feeding frequency information for call tone input signal to microprocessor via DC voltage converter providing galvanic separation
10/20/1993EP0565859A1 Telephone ringer circuit
10/19/1993US5255317 ISND (Integrated Services Digital Network) and POTS (Plain Old Telephone
10/14/1993WO1993020646A1 Combined supply voltage connection and call a.c. voltage generator and connection for analog telephone receiver stations in extension installations
10/13/1993EP0402360B1 Impedance synthesis multiple loop using filtering means
10/13/1993CN2143851Y DC power supply equipment for shared wave filter
10/13/1993CN1077321A Radio selective call receiver
10/12/1993US5253290 Circuit arrangement for the transmission of telecommunication signals
10/12/1993US5253289 In accordance with ringing signal sequences sent through telephone line
10/07/1993DE4211819A1 Hands-free telephone circuit with dynamic loudspeaker - provides loudspeaking and call tone output stages connected in parallel to loudspeaker for providing call tone signal
10/06/1993EP0564127A2 Chameleon apparatus housing unit
10/04/1993WO1993020645A1 Telephone line interface circuit with voltage switching
09/1993
09/28/1993US5249226 Apparatus for controlling a current supply device
09/23/1993DE4231938C1 Electronic circuit supplying calling signal to subscriber lines - interrupts calling order repeatedly for short intervals at zero-crossings for transitory re-imposition of supply voltage
09/21/1993US5247573 Telecommunications system comprising a circuit arrangement for at least one subscriber station
09/16/1993WO1993018609A1 Circuitry for superimposing small, low energy signals and large, essentially higher energy signals
09/16/1993WO1993018605A1 Hybrid fiber in the loop telephony system
09/16/1993DE4226423C1 Ringing signal display circuit for 2-wire telephone line - uses angularly offset sensor wires around outside of telephone line with evaluation of obtd. signal differences
09/16/1993CA2117555A1 Hybrid fiber in the loop telephony system
09/15/1993EP0560236A2 Method and switching-arrangement for transmission of digital signals on subscriber-lines
09/15/1993CN2142247Y Combination power supply using for communication network of countryside
09/09/1993DE4206762A1 Ringing-tone generator circuit for telephone subscriber's appts. - employs integrated circuit with fewer pins to detect zero-crossings of incoming signal and switch electro acoustic ringer
09/08/1993EP0559336A2 Apparatus for controlling a current supply device
09/02/1993WO1993017514A1 Telephone subscriber line circuit, components and methods
09/02/1993CA2130183A1 Telephone subscriber line circuit, components and methods
08/1993
08/25/1993EP0556742A1 Acoustic feedback suppression device particularly for auxiliary ringers in plug-in telephone systems
08/24/1993US5239580 Modem-telephone coupler
08/17/1993US5237606 Enhanced synchronous rectifier
08/12/1993DE4203477A1 Emergency operation circuitry for communication terminal devices - forms direct connection between mains and device with digital line when device current supply fails
08/10/1993CA1321239C Animated data display interleaving
08/05/1993DE4202874A1 Quiescent current supply circuit for telecommunication terminal - is either installed as auxiliary equipment or integrated into receiving appts. which is switched on when incoming message is recognised
08/04/1993EP0554196A1 Telephone line current modulator
08/04/1993EP0554192A1 Power regulator for the loudspeaker of a telephone unit
08/03/1993US5233649 Telephone ringing module
08/03/1993US5233641 Radio telephone equipment having a sounding device for generating alert tone indicative of response of called subscriber
08/03/1993US5233349 Signal transmission system
07/1993
07/23/1993WO1993015590A1 Radio with silent and audible alerts
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