GB1230054A - - Google Patents

Info

Publication number
GB1230054A
GB1230054A GB1230054DA GB1230054A GB 1230054 A GB1230054 A GB 1230054A GB 1230054D A GB1230054D A GB 1230054DA GB 1230054 A GB1230054 A GB 1230054A
Authority
GB
United Kingdom
Prior art keywords
current
feedback
diode
switch
transistor
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.)
Expired
Application number
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 AU53157/69A external-priority patent/AU429203B2/en
Application filed filed Critical
Publication of GB1230054A publication Critical patent/GB1230054A/en
Expired legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04M—TELEPHONIC COMMUNICATION
    • H04M19/00—Current supply arrangements for telephone systems
    • H04M19/001—Current supply source at the exchanger providing current to substations
    • H04M19/005—Feeding arrangements without the use of line transformers

Landscapes

  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Signal Processing (AREA)
  • Devices For Supply Of Signal Current (AREA)
  • Interface Circuits In Exchanges (AREA)
  • Amplifiers (AREA)

Abstract

1,230,054. Telephone exchange equipment; transistor switching circuits. MARCONI CO. Ltd. 19 Jan., 1970 [8 April, 1969], No. 2456/70. Headings H3T and H4K. Current taken from exchange battery terminal 2 to one leg 1 of an exchange line is fed over a first switch (transistors 3, 4), a second switch (diode 8) operating when current is drawn above a certain value so as to introduce feedback dependent on direct current in the line but substantially independent of speech components on account of the capacitor 7 shunting the resistor 6 across which the voltage to operate the second switch 8 is developed. The point at which feedback is switched in by diode 8 is set by divider 10, 11, and an auxiliary bias source. A transistor 9 is switched with diode 8 to give a low impedance shunt for the base of transistor 3. The transistors 3, 4 are of opposite type to compensate for temperature variation. By adjusting the current at which feedback becomes operative to a value below the holding current of a connection, establishment of a connection can be effected at a speed which is not retarded by the time constant of the feedback circuit. If the current at which feedback becomes operative is less than twice the holding current, the presence of feedback allows short duration tests to be made without fear of setting up double connections.
GB1230054D 1969-04-08 1970-01-19 Expired GB1230054A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
AU53157/69A AU429203B2 (en) 1969-04-08 Line feed circuit arrangement

Publications (1)

Publication Number Publication Date
GB1230054A true GB1230054A (en) 1971-04-28

Family

ID=3739213

Family Applications (1)

Application Number Title Priority Date Filing Date
GB1230054D Expired GB1230054A (en) 1969-04-08 1970-01-19

Country Status (1)

Country Link
GB (1) GB1230054A (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2392557A1 (en) * 1977-05-25 1978-12-22 Western Electric Co TELEPHONE POWER SUPPLY BY LOCAL BATTERY

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2392557A1 (en) * 1977-05-25 1978-12-22 Western Electric Co TELEPHONE POWER SUPPLY BY LOCAL BATTERY

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Legal Events

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