GB1481750A – Subscriber line interface circuit
– Google Patents
GB1481750A – Subscriber line interface circuit
– Google Patents
Subscriber line interface circuit
Info
Publication number
GB1481750A
GB1481750A
GB4527575A
GB4527575A
GB1481750A
GB 1481750 A
GB1481750 A
GB 1481750A
GB 4527575 A
GB4527575 A
GB 4527575A
GB 4527575 A
GB4527575 A
GB 4527575A
GB 1481750 A
GB1481750 A
GB 1481750A
Authority
GB
United Kingdom
Prior art keywords
circuits
circuit
line
feed
voltage
Prior art date
1974-12-23
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
GB4527575A
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.)
International Business Machines Corp
Original Assignee
International Business Machines Corp
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.)
1974-12-23
Filing date
1975-10-31
Publication date
1977-08-03
1975-10-17
Priority to DE19752546477
priority
Critical
patent/DE2546477C2/en
1975-10-17
Priority to FR7531773A
priority
patent/FR2288270A1/en
1975-10-31
Application filed by International Business Machines Corp
filed
Critical
International Business Machines Corp
1977-08-03
Publication of GB1481750A
publication
Critical
patent/GB1481750A/en
Status
Expired
legal-status
Critical
Current
Links
Espacenet
Global Dossier
Discuss
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
Abstract
1481750 Automatic exchange systems INTERNATIONAL BUSINESS MACHINES CORP 31 Oct 1975 [23 Dec 1974] 45275/75 Heading H4K In a subscriber line circuit the wires of the line are connected respectively to earth and to a power supply terminal via individual feed circuits and each feed circuit includes a gyrator circuit and a capacitor, the combination exhibiting an inductive impedance which operates as a low pass circuit. The feed circuits 34, 35, Fig. 2, including the gyrator circuits, e.g. 34a, approximate to resistances for D.C. currents and to inductances each of value α=R3.R2C1 for A.C. currents. One of the circuits 35, Fig. 1, is connectable to one of two power supply terminals – 30 v., – 48 v., the voltage – 30 v. being applied if the handset is on hook, if ringing current is applied or if the line current is above an upper tolerance level, and the voltage – 48 v. being applied if the handset is off-hook and the line current is below a lower tolerance level. Where no varistor circuitry is included in the substation circuits components Z2, T3 and R5, Fig. 2, are omitted from each feed circuit and a changeover of supply voltage requires no modifications of these circuits. However if varistor circuitry is included it is necessary to maintain the line current constant on voltage changeover and transistor T3 is turned off by a signal B from the selection circuit when the voltage is switched to – 30 v. and the Zener diode Z2 acts to maintain the line current constant. Transistor T2 is switched on to inhibit the feed circuit during ringing, by using a signal RX derived from the selection circuit. A differential amplifier arrangement 44, 45 (Fig. 1) is used to eliminate echoes which may occur due to the signal S2 on line 18 being fed via the feed circuits 34, 35 to the line 26; the circuit 45 is therefore designed to simulate the feed circuits in this respect. Diode arrangements 36-38, 40-43 are used to limit signal amplitude levels. Components 19, 20 constitute the line terminating impedance.
GB4527575A
1974-10-18
1975-10-31
Subscriber line interface circuit
Expired
GB1481750A
(en)
Priority Applications (2)
Application Number
Priority Date
Filing Date
Title
DE19752546477
DE2546477C2
(en)
1974-10-18
1975-10-17
Ship tank for storing or transporting a pressurized flowable medium
FR7531773A
FR2288270A1
(en)
1974-10-18
1975-10-17
Reservoirs for liquefied gases – for transport and storage under pressure with lobe-type compartmented tanks
Applications Claiming Priority (1)
Application Number
Priority Date
Filing Date
Title
CH1722074A
CH586984A5
(en)
1974-12-23
1974-12-23
Publications (1)
Publication Number
Publication Date
GB1481750A
true
GB1481750A
(en)
1977-08-03
Family
ID=4423697
Family Applications (1)
Application Number
Title
Priority Date
Filing Date
GB4527575A
Expired
GB1481750A
(en)
1974-10-18
1975-10-31
Subscriber line interface circuit
Country Status (6)
Country
Link
JP
(1)
JPS5186904A
(en)
CH
(1)
CH586984A5
(en)
DE
(1)
DE2551816C3
(en)
FR
(1)
FR2296339A1
(en)
GB
(1)
GB1481750A
(en)
IT
(1)
IT1049925B
(en)
Families Citing this family (10)
* Cited by examiner, † Cited by third party
Publication number
Priority date
Publication date
Assignee
Title
JPS5413715A
(en)
*
1977-07-01
1979-02-01
Nippon Telegr & Teleph Corp
Four-wire switching system
JPS5494811A
(en)
*
1978-01-11
1979-07-26
Hitachi Ltd
Supply system for channel current
JPS5494810A
(en)
*
1978-01-11
1979-07-26
Hitachi Ltd
Supply system for channel current
FR2414832A1
(en)
*
1978-01-13
1979-08-10
Labo Cent Telecommunicat
SUPPLY BRIDGE FOR TELEPHONE LINE
IT1159706B
(en)
*
1978-06-02
1987-03-04
Cselt Centro Studi Lab Telecom
USER LINE ELECTRONIC TELEPHONE CIRCUIT
NL7810086A
(en)
*
1978-10-06
1980-04-09
Philips Nv
POWER BRIDGE FOR A SUBSCRIBER FLOW.
US4254305A
(en)
*
1979-02-07
1981-03-03
International Telephone And Telegraph Corporation
Current limited subscriber line feed circuit
FR2460078B1
(en)
*
1979-06-25
1986-12-12
Trt Telecom Radio Electr
ELECTRONIC SUBSCRIBER
CA1157175A
(en)
*
1981-02-20
1983-11-15
Mitel Corporation
Power saving line circuit
DE3214624C2
(en)
*
1982-04-20
1986-05-28
Siemens AG, 1000 Berlin und 8000 München
Circuit arrangement for evaluating subscriber loop states in telephone systems, in particular in telephone branch exchange systems
Family Cites Families (1)
* Cited by examiner, † Cited by third party
Publication number
Priority date
Publication date
Assignee
Title
US3649769A
(en)
*
1970-10-28
1972-03-14
Gen Electric
Circuit for supplying direct current to a telephone line
1974
1974-12-23
CH
CH1722074A
patent/CH586984A5/xx
not_active
IP Right Cessation
1975
1975-10-31
GB
GB4527575A
patent/GB1481750A/en
not_active
Expired
1975-11-10
FR
FR7535236A
patent/FR2296339A1/en
active
Granted
1975-11-19
DE
DE19752551816
patent/DE2551816C3/en
not_active
Expired
1975-11-28
IT
IT2975975A
patent/IT1049925B/en
active
1975-12-19
JP
JP15069275A
patent/JPS5186904A/en
active
Granted
Also Published As
Publication number
Publication date
JPS5186904A
(en)
1976-07-30
DE2551816B2
(en)
1979-06-13
DE2551816C3
(en)
1980-10-30
IT1049925B
(en)
1981-02-10
DE2551816A1
(en)
1976-06-24
FR2296339A1
(en)
1976-07-23
FR2296339B1
(en)
1981-12-31
JPS5619784B2
(en)
1981-05-09
CH586984A5
(en)
1977-04-15
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Legal Events
Date
Code
Title
Description
1977-12-14
PS
Patent sealed
1987-06-17
PCNP
Patent ceased through non-payment of renewal fee
