GB1499983A - Audio-frequency amplifiers - Google Patents

Audio-frequency amplifiers

Info

Publication number
GB1499983A
GB1499983A GB961874A GB961874A GB1499983A GB 1499983 A GB1499983 A GB 1499983A GB 961874 A GB961874 A GB 961874A GB 961874 A GB961874 A GB 961874A GB 1499983 A GB1499983 A GB 1499983A
Authority
GB
United Kingdom
Prior art keywords
increase
path
resistors
march
transistor
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
GB961874A
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.)
General Electric Co PLC
Original Assignee
General Electric Co PLC
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 General Electric Co PLC filed Critical General Electric Co PLC
Priority to GB961874A priority Critical patent/GB1499983A/en
Publication of GB1499983A publication Critical patent/GB1499983A/en
Expired legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F1/00—Details of amplifiers with only discharge tubes, only semiconductor devices or only unspecified devices as amplifying elements
    • H03F1/34—Negative-feedback-circuit arrangements with or without positive feedback
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03G—CONTROL OF AMPLIFICATION
    • H03G3/00—Gain control in amplifiers or frequency changers without distortion of the input signal
    • 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
    • H03G3/3015—Automatic control in amplifiers having semiconductor devices in amplifiers suitable for low-frequencies, e.g. audio amplifiers the gain being continuously variable using diodes or transistors

Abstract

1499983 Automatic gain control GENERAL ELECTRIC CO Ltd 4 March 1975 [4 March 1974] 9618/74 Heading H4R An A.F. power amplifier having its gain reduced if its output current exceeds a predetermined limit, comprises a negative feed-back path, via 23, an F.E.T. 19 shunting said path, at least one resistor 14, 15 connected in series with an output current path of the amplifier, and means, including 16, 17 and 24, whereby excessive current causes the F.E.T. to be biased so as to increase the negative feedback and reduce the gain. Transistors 16, 17 and 24 are normally non-conducting, and the gate of F.E.T. 19 is earthed so that the source-drain resistance of 19 is low, the feedback being determined by the relative values of resistors 22 and 23. If the current in resistors 14 and/or 15 becomes high enough 16 and/or 17 are turned on, transistor 16 being controlled by transistor 24. Then a capacitor 18 begins to charge and the resistance of F.E.T. 19 to increase. Since 19 is in series with 22 the effect is to increase the negative feedback. It is stated that automatic gain control may be obtained up to approximately 50% overload.
GB961874A 1975-03-04 1975-03-04 Audio-frequency amplifiers Expired GB1499983A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB961874A GB1499983A (en) 1975-03-04 1975-03-04 Audio-frequency amplifiers

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB961874A GB1499983A (en) 1975-03-04 1975-03-04 Audio-frequency amplifiers

Publications (1)

Publication Number Publication Date
GB1499983A true GB1499983A (en) 1978-02-01

Family

ID=9875469

Family Applications (1)

Application Number Title Priority Date Filing Date
GB961874A Expired GB1499983A (en) 1975-03-04 1975-03-04 Audio-frequency amplifiers

Country Status (1)

Country Link
GB (1) GB1499983A (en)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2440650A1 (en) * 1978-10-31 1980-05-30 Hohner Ag Matth TRANSISTOR AMPLIFIER FOR ORCHESTRAS
GB2225187A (en) * 1988-11-18 1990-05-23 Mitel Corp Agc circuit
EP0463472A1 (en) * 1990-06-23 1992-01-02 IGEDO Internationale Modemesse Kronen GmbH u. Co. Kommanditgesellschaft Electronic muting circuit for electroacoustic systems or public address systems
EP0777403A2 (en) * 1995-11-29 1997-06-04 Angelo Martinazzi A system of sound diffusion, particularly for large spaces

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2440650A1 (en) * 1978-10-31 1980-05-30 Hohner Ag Matth TRANSISTOR AMPLIFIER FOR ORCHESTRAS
GB2225187A (en) * 1988-11-18 1990-05-23 Mitel Corp Agc circuit
GB2225187B (en) * 1988-11-18 1993-07-07 Mitel Corp Agc circuit
EP0463472A1 (en) * 1990-06-23 1992-01-02 IGEDO Internationale Modemesse Kronen GmbH u. Co. Kommanditgesellschaft Electronic muting circuit for electroacoustic systems or public address systems
EP0777403A2 (en) * 1995-11-29 1997-06-04 Angelo Martinazzi A system of sound diffusion, particularly for large spaces
EP0777403A3 (en) * 1995-11-29 2001-06-27 Angelo Martinazzi A system of sound diffusion, particularly for large spaces

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Legal Events

Date Code Title Description
PS Patent sealed
PCNP Patent ceased through non-payment of renewal fee