GB527677A - Improvements relating to telephone systems - Google Patents

Improvements relating to telephone systems

Info

Publication number
GB527677A
GB527677A GB1176239A GB1176239A GB527677A GB 527677 A GB527677 A GB 527677A GB 1176239 A GB1176239 A GB 1176239A GB 1176239 A GB1176239 A GB 1176239A GB 527677 A GB527677 A GB 527677A
Authority
GB
United Kingdom
Prior art keywords
instruments
arrangements
current
source
amplifier
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
GB1176239A
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.)
Alfred Graham & Co Ltd
Original Assignee
Alfred Graham & 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 Alfred Graham & Co Ltd filed Critical Alfred Graham & Co Ltd
Priority to GB1176239A priority Critical patent/GB527677A/en
Publication of GB527677A publication Critical patent/GB527677A/en
Expired legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04M—TELEPHONIC COMMUNICATION
    • H04M9/00—Arrangements for interconnection not involving centralised switching
    • H04M9/001—Two-way communication systems between a limited number of parties
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04M—TELEPHONIC COMMUNICATION
    • H04M1/00—Substation equipment, e.g. for use by subscribers
    • H04M1/60—Substation equipment, e.g. for use by subscribers including speech amplifiers
    • H04M1/6033—Substation equipment, e.g. for use by subscribers including speech amplifiers for providing handsfree use or a loudspeaker mode in telephone sets

Landscapes

  • Engineering & Computer Science (AREA)
  • Signal Processing (AREA)
  • Interconnected Communication Systems, Intercoms, And Interphones (AREA)

Abstract

527,677. Substation equipment. GRAHAM & CO., Ltd., A., and SMITH E. E. April 19, 1939, No. 11762. [Class 40 (iv)] In a system using instruments not requiring a source of current, auxiliary amplifying arrangements employing a local source are provided for received speech, said arrangements being connected to the communication circuit only when the current source is operative so that, otherwise, reception is not impaired. As shown, two stations are provided with instruments T of the balanced armature electromagnetic type, used for transmission and reception, although separate instruments may be provided. Calling is effected by operating generators G which connect themselves to the line and disconnect the corresponding instrument T, lamp L and alarm B being operated by calling current. Station S2 is also provided with loudspeaking receiving arrangements comprising a magneto-microphonic or thermionic amplifier ET and loudspeaker LS, the amplifier (microphonic as shown) being fed from a local battery CS. The amplifying circuits are completed by a relay A operated over switch hook contacts on a manual switch. When a thermionic amplifier is employed, its input is taken from the secondary of a transformer connected in series or parallel with instrument T2, relay A being arranged to short circuit or disconnect the primary winding as the case may be.
GB1176239A 1939-04-19 1939-04-19 Improvements relating to telephone systems Expired GB527677A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB1176239A GB527677A (en) 1939-04-19 1939-04-19 Improvements relating to telephone systems

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB1176239A GB527677A (en) 1939-04-19 1939-04-19 Improvements relating to telephone systems

Publications (1)

Publication Number Publication Date
GB527677A true GB527677A (en) 1940-10-14

Family

ID=9992237

Family Applications (1)

Application Number Title Priority Date Filing Date
GB1176239A Expired GB527677A (en) 1939-04-19 1939-04-19 Improvements relating to telephone systems

Country Status (1)

Country Link
GB (1) GB527677A (en)

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