IE872384L - Speech circuit for telephone - Google Patents

Speech circuit for telephone

Info

Publication number
IE872384L
IE872384L IE872384A IE238487A IE872384L IE 872384 L IE872384 L IE 872384L IE 872384 A IE872384 A IE 872384A IE 238487 A IE238487 A IE 238487A IE 872384 L IE872384 L IE 872384L
Authority
IE
Ireland
Prior art keywords
loudspeaker
input
amplifier
ic1b
feedback
Prior art date
Application number
IE872384A
Original Assignee
Lake Electronic Tech
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 Lake Electronic Tech filed Critical Lake Electronic Tech
Priority to IE872384A priority Critical patent/IE872384L/en
Priority to ZA876822A priority patent/ZA876822B/en
Priority to GB8721477A priority patent/GB2209646B/en
Priority to NL8702310A priority patent/NL8702310A/en
Priority to SE8704927A priority patent/SE8704927L/en
Priority to CN88106466A priority patent/CN1032092A/en
Priority to AU21910/88A priority patent/AU2191088A/en
Publication of IE872384L publication Critical patent/IE872384L/en

Links

Classifications

    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03G—CONTROL OF AMPLIFICATION
    • H03G3/00—Gain control in amplifiers or frequency changers
    • H03G3/20—Automatic control
    • H03G3/30—Automatic control in amplifiers having semiconductor devices
    • H03G3/3005—Automatic control in amplifiers having semiconductor devices in amplifiers suitable for low-frequencies, e.g. audio amplifiers
    • H03G3/301—Automatic control in amplifiers having semiconductor devices in amplifiers suitable for low-frequencies, e.g. audio amplifiers the gain being continuously variable
    • 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)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • Amplifiers (AREA)

Abstract

The input terminals 3, 4 of an audio amplifier Ic1a, Ic1b, are shunted by a variable impedance FET T1 controlled by feedback to regulate the output to a loudspeaker 102 to accommodate varying levels of input applied from telephone line 105, 106. Feedback is derived by transistor T2 which, beyond a level of power drawn by Ic1b, as detected by R5 in the base circuit, controls FET T1 to attenuate the input signal. A ringing signal generator 103 drives the loudspeaker when signals on terminals 110, 111 isolate the loudspeaker from the audio input and couple the generator. A control signal on terminal 113 connects the rail 115 of the amplifier to ground thus switching off the amplifier during dialling or when the station is in a non-loudspeaking mode. <IMAGE> [GB2209646A]
IE872384A 1987-09-07 1987-09-07 Speech circuit for telephone IE872384L (en)

Priority Applications (7)

Application Number Priority Date Filing Date Title
IE872384A IE872384L (en) 1987-09-07 1987-09-07 Speech circuit for telephone
ZA876822A ZA876822B (en) 1987-09-07 1987-09-11 A speech circuit for a telephone
GB8721477A GB2209646B (en) 1987-09-07 1987-09-11 A speech circuit for a telephone
NL8702310A NL8702310A (en) 1987-09-07 1987-09-28 VOICE CHAIN FOR A TELEPHONE.
SE8704927A SE8704927L (en) 1987-09-07 1987-12-10 SPEECH CIRCLE BY PHONE
CN88106466A CN1032092A (en) 1987-09-07 1988-09-06 The speech circuit of phone
AU21910/88A AU2191088A (en) 1987-09-07 1988-09-06 A speech circuit for a telephone

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
IE872384A IE872384L (en) 1987-09-07 1987-09-07 Speech circuit for telephone

Publications (1)

Publication Number Publication Date
IE872384L true IE872384L (en) 1989-03-07

Family

ID=11034497

Family Applications (1)

Application Number Title Priority Date Filing Date
IE872384A IE872384L (en) 1987-09-07 1987-09-07 Speech circuit for telephone

Country Status (7)

Country Link
CN (1) CN1032092A (en)
AU (1) AU2191088A (en)
GB (1) GB2209646B (en)
IE (1) IE872384L (en)
NL (1) NL8702310A (en)
SE (1) SE8704927L (en)
ZA (1) ZA876822B (en)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
AU622524B2 (en) * 1989-03-16 1992-04-09 Alcatel Australia Limited Receiver mute circuit

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1263850B (en) * 1965-11-10 1968-03-21 Telefunken Patent Electrically adjustable voltage divider with low non-linear distortion
GB1207339A (en) * 1967-12-07 1970-09-30 Standard Telephones Cables Ltd Loud speaking telephone circuits
SE320599B (en) * 1968-03-26 1970-02-09 Bofors Ab
US3533006A (en) * 1968-11-04 1970-10-06 Collins Radio Co Infinite range electronics gain control circuit
JPS5549451B2 (en) * 1972-08-30 1980-12-12
FR2522451B1 (en) * 1982-03-01 1988-10-14 Audibel IMPROVEMENT IN THE AUTOMATIC GAIN CONTROL CIRCUIT OF A TRANSISTOR AMPLIFICATION SYSTEM AND HEARING CORRECTION APPARATUS PROVIDED WITH SUCH A CIRCUIT

Also Published As

Publication number Publication date
CN1032092A (en) 1989-03-29
GB2209646A (en) 1989-05-17
AU2191088A (en) 1989-03-09
ZA876822B (en) 1988-05-25
NL8702310A (en) 1989-04-03
SE8704927D0 (en) 1987-12-10
GB2209646B (en) 1991-06-12
GB8721477D0 (en) 1987-10-21
SE8704927L (en) 1989-03-08

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