GB736988A - Improvements in or relating to loudspeaking telephone systems - Google Patents

Improvements in or relating to loudspeaking telephone systems

Info

Publication number
GB736988A
GB736988A GB55553A GB55553A GB736988A GB 736988 A GB736988 A GB 736988A GB 55553 A GB55553 A GB 55553A GB 55553 A GB55553 A GB 55553A GB 736988 A GB736988 A GB 736988A
Authority
GB
United Kingdom
Prior art keywords
relay
circuit
incoming
signals
outgoing
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
GB55553A
Inventor
Philip Norton Roseby
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.)
Automatic Telephone and Electric Co Ltd
Original Assignee
Automatic Telephone and Electric 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 Automatic Telephone and Electric Co Ltd filed Critical Automatic Telephone and Electric Co Ltd
Priority to GB55553A priority Critical patent/GB736988A/en
Publication of GB736988A publication Critical patent/GB736988A/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
    • H04M1/60—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

736,988. Two-way transmission. AUTOMATIC TELEPHONE & ELECTRIC CO., Ltd. Nov. 18, 1953 [Jan. 8, 1953], No. 555/53. Class 40 (4). In a telephone.system having voice-operated switching for preventing acoustic reaction between loudspeaker-equipped substations by introducing attenuation in either the incoming or outgoing paths IC, OG of a 4-wire circuit, the line transformers TR1, TR2 have tertiary windings connected through rectifiers MR1, MR2.and smoothing condensers C1, C2 to resistors R3, R4 at which the rectified voltages are combined in opposition to control an attenuation-switching relay SR over a thermionic valve V1. If incoming signals predominate, relay SR releases and closes an attenuating circuit comprising resistor R2 in the outgoing path from a microphone circuit MIC. In this condition the incoming signals are applied directly to an amplifier and loud-speaker circuit LS.over a volumelimiting bridge comprising resistors R7, R8 and metal filament lamps LP1, LP2. When outgoing signals predominate, relay SR is pulled up by increased anode current and closes an attenuating circuit comprising resistor R1 in the incoming path. By arranging the valveoperating conditions to be such that its quiescent anode current is sufficient to hold SR operated but not to pull up the relay if released, the transmission direction which was last in use before cessation of all signals is. maintained. Alternatively the bias of the valve may be adjusted to give priority to one direction of transmission.
GB55553A 1953-01-08 1953-01-08 Improvements in or relating to loudspeaking telephone systems Expired GB736988A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB55553A GB736988A (en) 1953-01-08 1953-01-08 Improvements in or relating to loudspeaking telephone systems

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB55553A GB736988A (en) 1953-01-08 1953-01-08 Improvements in or relating to loudspeaking telephone systems

Publications (1)

Publication Number Publication Date
GB736988A true GB736988A (en) 1955-09-14

Family

ID=9706442

Family Applications (1)

Application Number Title Priority Date Filing Date
GB55553A Expired GB736988A (en) 1953-01-08 1953-01-08 Improvements in or relating to loudspeaking telephone systems

Country Status (1)

Country Link
GB (1) GB736988A (en)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3060265A (en) * 1960-01-26 1962-10-23 Itt Conference call circuit
US3065300A (en) * 1958-09-30 1962-11-20 Modern Telephones Great Britai Loudspeaking telephone systems
US3075045A (en) * 1960-08-29 1963-01-22 Bell Telephone Labor Inc Speakerphone
US3126448A (en) * 1964-03-24 Station

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3126448A (en) * 1964-03-24 Station
US3065300A (en) * 1958-09-30 1962-11-20 Modern Telephones Great Britai Loudspeaking telephone systems
US3060265A (en) * 1960-01-26 1962-10-23 Itt Conference call circuit
US3075045A (en) * 1960-08-29 1963-01-22 Bell Telephone Labor Inc Speakerphone

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