GB792475A - Improvements in or relating to telephone systems - Google Patents

Improvements in or relating to telephone systems

Info

Publication number
GB792475A
GB792475A GB1819255A GB1819255A GB792475A GB 792475 A GB792475 A GB 792475A GB 1819255 A GB1819255 A GB 1819255A GB 1819255 A GB1819255 A GB 1819255A GB 792475 A GB792475 A GB 792475A
Authority
GB
United Kingdom
Prior art keywords
frequency
line
transistor
output
substations
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
GB1819255A
Inventor
Ronald George John Martin
Howard Raymond Pate
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.)
Plessey Co Ltd
Original Assignee
Plessey Co 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
Application filed by Plessey Co Ltd filed Critical Plessey Co Ltd
Priority to GB1819255A priority Critical patent/GB792475A/en
Publication of GB792475A publication Critical patent/GB792475A/en
Expired legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04Q—SELECTING
    • H04Q5/00—Selecting arrangements wherein two or more subscriber stations are connected by the same line to the exchange

Landscapes

  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Devices For Supply Of Signal Current (AREA)

Abstract

792,475. Party-line systems. PLESSEY CO., Ltd. June 19, 1956 [June 23, 1955], No. 18192/55. Class 40 (4). In a party-line system suitable for use in firing mines, each subscriber is allocated a particular supersonic calling frequency which is accepted by a filter whose output enables ringing current to be applied to a bell. As shown, a substation comprises a telephone A and a transistor oscillator B whose supersonic frequency is controlled by a rotary switch Bl and which is energized by the push-button B2 to send the appropriate frequency to line. At the wanted station the frequency is accepted by a filter unit C which also comprises a transistor amplifier and rectifier. The output therefrom enables a transistor ringing current generator D of the type described in Specification 784,444, the output of which rings the bell E. A further filter accepting a frequency common to all the substations may be provided to enable all substations to be called simultaneously in the event of an emergency. The line may be terminated on a switchboard provided with equipment similar to that of a substation.
GB1819255A 1955-06-23 1955-06-23 Improvements in or relating to telephone systems Expired GB792475A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB1819255A GB792475A (en) 1955-06-23 1955-06-23 Improvements in or relating to telephone systems

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB1819255A GB792475A (en) 1955-06-23 1955-06-23 Improvements in or relating to telephone systems

Publications (1)

Publication Number Publication Date
GB792475A true GB792475A (en) 1958-03-26

Family

ID=10108236

Family Applications (1)

Application Number Title Priority Date Filing Date
GB1819255A Expired GB792475A (en) 1955-06-23 1955-06-23 Improvements in or relating to telephone systems

Country Status (1)

Country Link
GB (1) GB792475A (en)

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