GB771885A - Improvements in or relating to telephone subscribers' apparatus - Google Patents

Improvements in or relating to telephone subscribers' apparatus

Info

Publication number
GB771885A
GB771885A GB379854A GB379854A GB771885A GB 771885 A GB771885 A GB 771885A GB 379854 A GB379854 A GB 379854A GB 379854 A GB379854 A GB 379854A GB 771885 A GB771885 A GB 771885A
Authority
GB
United Kingdom
Prior art keywords
detector
exchange
oscillator
line
oscillation
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
GB379854A
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 GB379854A priority Critical patent/GB771885A/en
Publication of GB771885A publication Critical patent/GB771885A/en
Expired legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04M—TELEPHONIC COMMUNICATION
    • H04M1/00—Substation equipment, e.g. for use by subscribers
    • H04M1/68—Circuit arrangements for preventing eavesdropping

Landscapes

  • Engineering & Computer Science (AREA)
  • Signal Processing (AREA)
  • Alarm Systems (AREA)

Abstract

771,885. Substation equipment. GENERAL ELECTRIC CO., Ltd., and BLOCH, A. May 9, 1955 [Feb. 9, 1954], No. 3798/54. Drawings to Specification. Class 40 (4). A subscriber's set is provided with a transistor oscillator arranged to transmit oscillations to the exchange where a detector actuates an alarm if the oscillations cease due to a line break, short circuit or other cause. In the case of a central battery exchange the oscillator may receive its power supply over the line from the exchange battery. The oscillation may be supersonic, or of audio-frequency; arrangements being made to disconnect the oscillator in the latter case when the call is made. The application of the oscillation may be intermittent to conserve power supplies. The detector which comprises a transistor operating as an amplifier-rectifier operates a relay controlling an alarm device. An individual detector per line may be provided or a single detector may periodically scan a plurality of lines.
GB379854A 1954-02-09 1954-02-09 Improvements in or relating to telephone subscribers' apparatus Expired GB771885A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB379854A GB771885A (en) 1954-02-09 1954-02-09 Improvements in or relating to telephone subscribers' apparatus

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB379854A GB771885A (en) 1954-02-09 1954-02-09 Improvements in or relating to telephone subscribers' apparatus

Publications (1)

Publication Number Publication Date
GB771885A true GB771885A (en) 1957-04-03

Family

ID=9765097

Family Applications (1)

Application Number Title Priority Date Filing Date
GB379854A Expired GB771885A (en) 1954-02-09 1954-02-09 Improvements in or relating to telephone subscribers' apparatus

Country Status (1)

Country Link
GB (1) GB771885A (en)

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