GB620897A - Improvements in or relating to substation telephone sets - Google Patents

Improvements in or relating to substation telephone sets

Info

Publication number
GB620897A
GB620897A GB2876/47A GB287647A GB620897A GB 620897 A GB620897 A GB 620897A GB 2876/47 A GB2876/47 A GB 2876/47A GB 287647 A GB287647 A GB 287647A GB 620897 A GB620897 A GB 620897A
Authority
GB
United Kingdom
Prior art keywords
impedance
terminals
link
line
lines
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
GB2876/47A
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.)
Kellogg Switchboard and Supply Co
Original Assignee
Kellogg Switchboard and Supply Co
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 Kellogg Switchboard and Supply Co filed Critical Kellogg Switchboard and Supply Co
Publication of GB620897A publication Critical patent/GB620897A/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
    • H04M1/58—Anti-side-tone circuits
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01C—MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY
    • G01C17/00—Compasses; Devices for ascertaining true or magnetic north for navigation or surveying purposes
    • G01C17/02—Magnetic compasses
    • G01C17/04—Magnetic compasses with north-seeking magnetic elements, e.g. needles
    • G01C17/20—Observing the compass card or needle
    • G01C17/26—Observing the compass card or needle using electric pick-offs for transmission to final indicator, e.g. photocell

Landscapes

  • Engineering & Computer Science (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Remote Sensing (AREA)
  • Signal Processing (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Rectifiers (AREA)

Abstract

620,897. Substation equipment; anti-sidetone circuits. KELLOGG SWITCHBOARD & SUPPLY CO. Jan. 30, 1947, No. 2876. Convention date, July 13, 1945. [Class 40 (iv)] In a telephone set for anti-side-tone working over common battery circuits, terminals 34, 35, 36 are provided to enable an impedance 78 to be included in or excluded from the circuit according to the length of line to which the set is connected. For long lines the impedance 78 is included in the line balance 62, 76 over induction coil winding 75 to augment the effect of the resistance 76, terminals 34, 35 being connected by a link 19 (Fig. 2). For short lines the link connects terminals 34, 36 (Fig. 4) so that the impedance 78 is in series with the line L1, L2 and induction coil winding 74, and thus serves to limit the flow of direct current through the transmitter in addition to maintaining balanced operation. For lines of medium length the link 19 is positioned to connect all three terminals and short circuit the impedance 78 (Fig. 3).
GB2876/47A 1945-07-13 1947-01-30 Improvements in or relating to substation telephone sets Expired GB620897A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US620897XA 1945-07-13 1945-07-13

Publications (1)

Publication Number Publication Date
GB620897A true GB620897A (en) 1949-03-31

Family

ID=22040152

Family Applications (1)

Application Number Title Priority Date Filing Date
GB2876/47A Expired GB620897A (en) 1945-07-13 1947-01-30 Improvements in or relating to substation telephone sets

Country Status (1)

Country Link
GB (1) GB620897A (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1005124B (en) * 1952-09-27 1957-03-28 Standard Elektrik Ag Telephone device, especially subscriber set, with changeable reference damping

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1005124B (en) * 1952-09-27 1957-03-28 Standard Elektrik Ag Telephone device, especially subscriber set, with changeable reference damping

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