GB8628361D0 - Telephone apparatus - Google Patents

Telephone apparatus

Info

Publication number
GB8628361D0
GB8628361D0 GB8628361A GB8628361A GB8628361D0 GB 8628361 D0 GB8628361 D0 GB 8628361D0 GB 8628361 A GB8628361 A GB 8628361A GB 8628361 A GB8628361 A GB 8628361A GB 8628361 D0 GB8628361 D0 GB 8628361D0
Authority
GB
United Kingdom
Prior art keywords
circuit
impedance circuit
exchange
primary impedance
primary
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
GB8628361A
Other versions
GB2184630A (en
GB2184630B (en
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Lake Electronic Technologies Ltd
Original Assignee
Lake Electronic Technologies Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from IE310485A external-priority patent/IE853104L/en
Application filed by Lake Electronic Technologies Ltd filed Critical Lake Electronic Technologies Ltd
Publication of GB8628361D0 publication Critical patent/GB8628361D0/en
Publication of GB2184630A publication Critical patent/GB2184630A/en
Application granted granted Critical
Publication of GB2184630B publication Critical patent/GB2184630B/en
Granted legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04M—TELEPHONIC COMMUNICATION
    • H04M3/00—Automatic or semi-automatic exchanges
    • H04M3/005—Interface circuits for subscriber lines
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F11/00—Error detection; Error correction; Monitoring
    • G06F11/07—Responding to the occurrence of a fault, e.g. fault tolerance
    • G06F11/14—Error detection or correction of the data by redundancy in operation
    • G06F11/1402—Saving, restoring, recovering or retrying
    • G06F11/1415—Saving, restoring, recovering or retrying at system level
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03K—PULSE TECHNIQUE
    • H03K17/00—Electronic switching or gating, i.e. not by contact-making and –breaking
    • H03K17/22—Modifications for ensuring a predetermined initial state when the supply voltage has been applied
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04M—TELEPHONIC COMMUNICATION
    • H04M1/00—Substation equipment, e.g. for use by subscribers
    • H04M1/738—Interface circuits for coupling substations to external telephone lines
    • H04M1/76—Compensating for differences in line impedance
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04M—TELEPHONIC COMMUNICATION
    • H04M7/00—Arrangements for interconnection between switching centres
    • H04M7/0096—Trunk circuits

Landscapes

  • Engineering & Computer Science (AREA)
  • Signal Processing (AREA)
  • Theoretical Computer Science (AREA)
  • Quality & Reliability (AREA)
  • Physics & Mathematics (AREA)
  • General Engineering & Computer Science (AREA)
  • General Physics & Mathematics (AREA)
  • Sub-Exchange Stations And Push- Button Telephones (AREA)

Abstract

A private automatic exchange comprising a plurality of extension line circuits and exchange line circuits. Each exchange line circuit comprises terminals (1) and (2) for connecting the circuit to an exchange line. Terminals (3) and (4) connect the circuit to a switching matrix of the private automatic branch exchange. The circuit comprises a current sink circuit which comprises a primary impedance circuit (21) and a secondary impedance circuit (22). The circuit (21) comprises resistors R31, R32, R33 and R40 and a Darlington pair of transistors T24 and T25. The secondary impedance circuit comprises a resistor R37 shunted across the primary impedance circuit by a field effect transistor T26. This is responsive to the level of current flowing in the primary impedance circuit. When the current flowing in the primary impedance circuit reaches a predetermined level, a transistor T27 is switched on, thus switching on the field effect transistor T26. <IMAGE>
GB8628361A 1985-12-10 1986-11-27 A telephone apparatus Granted GB2184630A (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
IE310485A IE853104L (en) 1985-12-10 1985-12-10 Telephone apparatus
IE310585 1985-12-10
IE65986 1986-03-13

Publications (3)

Publication Number Publication Date
GB8628361D0 true GB8628361D0 (en) 1986-12-31
GB2184630A GB2184630A (en) 1987-06-24
GB2184630B GB2184630B (en) 1989-10-11

Family

ID=27270318

Family Applications (1)

Application Number Title Priority Date Filing Date
GB8628361A Granted GB2184630A (en) 1985-12-10 1986-11-27 A telephone apparatus

Country Status (2)

Country Link
BE (1) BE905887A (en)
GB (1) GB2184630A (en)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3804216A1 (en) * 1988-02-11 1989-08-24 Telefonbau & Normalzeit Gmbh CIRCUIT ARRANGEMENT FOR EXTERNAL LINE TRANSMISSION OF COMMUNICATION SWITCHING SYSTEMS, ESPECIALLY TELEPHONE EXTENSION SYSTEMS
GB2220820B (en) * 1988-07-13 1992-07-08 Philips Electronic Associated Telephone line loop current regulator

Also Published As

Publication number Publication date
GB2184630A (en) 1987-06-24
BE905887A (en) 1987-04-01
GB2184630B (en) 1989-10-11

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Legal Events

Date Code Title Description
PCNP Patent ceased through non-payment of renewal fee