GB884832A - Improvements in or relating to telephone subscriber's line circuits - Google Patents

Improvements in or relating to telephone subscriber's line circuits

Info

Publication number
GB884832A
GB884832A GB3637458A GB3637458A GB884832A GB 884832 A GB884832 A GB 884832A GB 3637458 A GB3637458 A GB 3637458A GB 3637458 A GB3637458 A GB 3637458A GB 884832 A GB884832 A GB 884832A
Authority
GB
United Kingdom
Prior art keywords
lamp
current
subscriber
telephone subscriber
resistor
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
GB3637458A
Inventor
Alan John Bayliss
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.)
General Electric Co PLC
Original Assignee
General Electric Co PLC
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
Application filed by General Electric Co PLC filed Critical General Electric Co PLC
Priority to GB3637458A priority Critical patent/GB884832A/en
Publication of GB884832A publication Critical patent/GB884832A/en
Expired legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04M—TELEPHONIC COMMUNICATION
    • H04M3/00—Automatic or semi-automatic exchanges
    • H04M3/22—Arrangements for supervision, monitoring or testing
    • H04M3/2272—Subscriber line supervision circuits, e.g. call detection circuits

Landscapes

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

Abstract

884,832. Automatic exchange systems. GENERAL ELECTRIC CO. Ltd. Feb. 12, 1960 [Nov. 12, 1958], No. 36374/58. Class 40 (4). [Also in Group XL (b)] A circuit for terminating a telephone subscriber's line comprises a lamp 10 at the exchange, Fig. 1, which is lighted when the subscriber lifts his handset, and a photocell 12 which causes a current to flow in resistor 14 when the cell is illuminated. A Zener diode 11 limits the current in the lamp 10 so that the light output is independent of subscriber line current. A diode 16 ensures that the voltage across resistor 14 does not exceed 5 volts. The lamp 10 and cell 12 are formed as one unit, Fig. 2, the photo-conductive element 23 and electrodes 20, 21 being against the lamp bulb 22. The whole is encased in an opaque resin. The circuit is stated to be of particular use in electronic exchanges of the type described in Specification 856,732.
GB3637458A 1958-11-12 1958-11-12 Improvements in or relating to telephone subscriber's line circuits Expired GB884832A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB3637458A GB884832A (en) 1958-11-12 1958-11-12 Improvements in or relating to telephone subscriber's line circuits

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB3637458A GB884832A (en) 1958-11-12 1958-11-12 Improvements in or relating to telephone subscriber's line circuits

Publications (1)

Publication Number Publication Date
GB884832A true GB884832A (en) 1961-12-20

Family

ID=10387562

Family Applications (1)

Application Number Title Priority Date Filing Date
GB3637458A Expired GB884832A (en) 1958-11-12 1958-11-12 Improvements in or relating to telephone subscriber's line circuits

Country Status (1)

Country Link
GB (1) GB884832A (en)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3783198A (en) * 1971-03-18 1974-01-01 Gte Automatic Electric Lab Inc Battery reversal detection
US3819866A (en) * 1972-12-18 1974-06-25 Bell Telephone Labor Inc Light coupled loop current detector
US3944752A (en) * 1974-11-01 1976-03-16 Porta Systems Corporation Telephone line status indicator
US3971898A (en) * 1974-04-09 1976-07-27 Iwatsu Electric Co., Ltd. Visual indicating control circuit in key telephone system

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3783198A (en) * 1971-03-18 1974-01-01 Gte Automatic Electric Lab Inc Battery reversal detection
US3819866A (en) * 1972-12-18 1974-06-25 Bell Telephone Labor Inc Light coupled loop current detector
US3971898A (en) * 1974-04-09 1976-07-27 Iwatsu Electric Co., Ltd. Visual indicating control circuit in key telephone system
US3944752A (en) * 1974-11-01 1976-03-16 Porta Systems Corporation Telephone line status indicator

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