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)
12/1990
12/31/1990CA2018510A1 Self-powered base and remote telephone communication set
12/27/1990EP0232317B1 Apparatus for providing a ground reference for telephone customer special circuits powered from a floating battery feed
12/19/1990EP0402360A1 Impedance synthesis multiple loop using filtering means.
12/18/1990US4979208 Method and apparatus for electronic payphone open switch interval management
12/13/1990WO1990013198A3 Device for transmitting information
12/04/1990US4975949 Electronic headset telephone
11/1990
11/28/1990EP0399997A2 Powering circuit for alternating call signals
11/28/1990EP0399520A2 A radio communication system
11/26/1990CA2017551A1 Hearing assist telephone
11/20/1990US4972466 Digital composite tone alerting
11/20/1990US4972452 Digital bypass for telephone system
11/06/1990US4969186 Telephone message waiting system and apparatus
11/06/1990US4969180 Cordless pen telephone handset
11/01/1990WO1990013198A2 Device for transmitting information
10/1990
10/31/1990CN1046645A 线路接口电路 Line Interface Circuit
10/25/1990DE3913754A1 Steuereinrichtung Controller
10/24/1990EP0393822A2 Line interface circuit
10/23/1990US4965692 Overload detector and protection circuit
10/17/1990EP0391918A1 Telephone accessory
10/16/1990US4964158 Power supply for telephone exchange
10/09/1990US4962545 Volume level retention in a pager
10/09/1990US4962527 Series ringing signal generator
10/09/1990US4962520 Composite ringing and coin control voltage detector and method
10/03/1990CN1009897B Active impedance line feed circuit
10/03/1990CN1009896B Key telephone system
10/02/1990US4961222 Apparatus in a telecommunication system for supplying power to a telephone set
10/02/1990US4961220 Power management in a microprocessor-controlled battery-powered telephone device
10/02/1990US4961219 Circuit for synthesizing an impedance across the tip and ring leads of a telephone line circuit
09/1990
09/25/1990US4959853 Frequency responsive selective ringing circuit
09/18/1990CA1274329A1 Telephone system and method operated from central office loop current
09/04/1990US4955053 Solid state ringing switch
08/1990
08/28/1990US4953207 Electronic telephone set
08/28/1990US4953200 Private branch exchange capable of discriminating different types of telephone sets connected thereto
08/28/1990US4953055 System and a protection and remote power-feeding device for equipment connected by two transformers to a four-wire transmission link
08/23/1990WO1990009715A1 Circuit arrangement for a telephone subscriber station
08/23/1990WO1990009703A1 Amplifier arrangement and communication line circuit using same
08/23/1990DE3905031A1 Schaltungsanordnung fuer eine fernsprechteilnehmerstation Circuit arrangement for a telephone-subscriber station
08/21/1990US4951039 Animated data display interleaving
08/16/1990EP0382069A2 Method and circuit arrangement for adjusting the volume in a mobile telephone
08/08/1990EP0381214A2 Telephone having touch sensor for responding to a call
08/08/1990EP0381105A1 Electronic connecting device for a subscriber line
07/1990
07/31/1990CA2008917A1 Electronic device for connecting a subscriber line
07/31/1990CA1272319A1 Intrinsically safe telephone
07/31/1990CA1272318A1 Integrated ringing circuit and a ring trip circuit for the same
07/20/1990WO1990008441A1 Earth detecting circuit
07/17/1990US4942600 Communication apparatus for generating a call signal from a telephone set to a data terminal
07/12/1990WO1990007835A1 A telephone subset arrangement
07/12/1990WO1990007834A1 Impedance synthesis multiple loop using filtering means
07/12/1990DE3900647A1 Circuit arrangement for connecting different telecommunications devices to the analog exchange line
07/04/1990EP0376191A1 Power supply switch for electrical equipment, and remote control terminal apparatus provided with such a switch
07/03/1990US4939775 Telephone ringing detector
06/1990
06/28/1990DE3843083A1 Voltage supply for the microprocessor of a line-fed telephone station
06/27/1990EP0375250A2 Electronic ringing signal generator
06/27/1990CN1043417A Telephone protection circuit
06/20/1990EP0373887A2 Telephone ringing detector
06/19/1990US4935960 Battery feed circuit
06/19/1990US4935928 DC supply for an S-bus in ISDN
06/13/1990EP0372673A2 Telephone protection circuit
06/13/1990EP0372616A1 Electronic telephone set
05/1990
05/15/1990US4926467 Line card with distributed signaling voltages
05/15/1990US4926466 Permanent connection public telephone appliance
05/15/1990US4926459 Hearing assist telephone
05/15/1990US4926458 Low power control apparatus for a coin operated telephone
05/14/1990EP0282578A4 Quad exchange power controller.
05/09/1990EP0367270A2 Data circuit-terminating equipment with power source device attached thereto
05/09/1990EP0366991A2 Method and device to keep low the power absorbed by a telephone interface circuit, in the "on-hook" state of the line
05/08/1990US4924511 Ring signal generator for generating ring signals of different frequencies and power levels in response to user selection
05/08/1990US4924193 Volume control circuit for use in portable telephone or the like
05/08/1990CA1268873A1 Line interface circuit
05/08/1990CA1268872A1 Ringing circuit
05/01/1990US4922531 Line interface circuit
05/01/1990US4922527 Small electronic apparatus
04/1990
04/25/1990CN1007770B Circuit arrangement for protecting electronic device to counteract excessive load
04/24/1990US4920561 Ring detector for telephone line
04/18/1990EP0363362A1 Telephone subset circuit arrangement
04/12/1990DE3833745A1 Changeover switching device for a number of extensions to be operated on a common subscriber line
04/11/1990EP0174942B1 Circuit arrangement for the electric supply of devices in a telephone set
04/10/1990US4916735 Power-supply transfer apparatus for telephone
04/10/1990US4916734 Apparatus for separating dc current and ac current components of a composite signal
04/10/1990CA1267738A1 Telephone set comprising a line voltage stabilizer having a dc supply point
04/04/1990EP0361158A2 Subscriber connecting circuit for a digital time division switching exchange
04/04/1990EP0361144A2 Circuit arrangement for an electronic subscriber connection circuit
04/03/1990US4914693 Telephone subscriber circuit
03/1990
03/28/1990EP0360227A2 Terminating circuit in a battery feed circuit of an electronic exchange system
03/28/1990EP0360056A1 Circuitry for telecommunication, especially telephone exchanges with switching devices powered by a service voltage and an auxiliary voltage
03/20/1990US4910769 Telephone line interface circuit
03/13/1990US4908857 Isolated drive circuit
03/13/1990US4908856 Switching voltage regulator for an interface circuit in a telephone subscriber line
03/13/1990US4908854 Apparatus for connecting and disconnecting a ringing signal to a called subscriber
02/1990
02/28/1990EP0356109A2 Electronic inductor
02/22/1990DE3926149A1 Circuit board for telephone exchange - has interface circuit connected via lines to telephone sets and relays controlling connections of bus to line wires to call done generator
02/14/1990EP0354477A1 Method and device for the generation of pulse sequences for a number of signal lines
02/08/1990DE3826765A1 Circuit arrangement for feeding electronic components in communications terminals via the connection lines
02/06/1990US4899382 Telephone circuit using DC blocked transformer and negative impedance technique
02/01/1990DE3826002A1 Circuit arrangement for feeding an amplifier from the public telephone network
01/1990
01/31/1990CN1039340A Control system for common line communication of data terminal and telephone
01/30/1990US4897872 Interface circuit between a subscriber's telephone line and exchange control components, with reduced current consumption in the case of a grounded cable
01/25/1990DE3834867C1 Circuit arrangement for the parallel connection of power supply devices
01/25/1990DE3824339A1 Method for identifying and feeding telephone terminals
01/23/1990US4896352 Telephone set circuit including an overvoltage protection
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