GB892921A - Improvements in transistor amplifiers - Google Patents

Improvements in transistor amplifiers

Info

Publication number
GB892921A
GB892921A GB35025/58A GB3502558A GB892921A GB 892921 A GB892921 A GB 892921A GB 35025/58 A GB35025/58 A GB 35025/58A GB 3502558 A GB3502558 A GB 3502558A GB 892921 A GB892921 A GB 892921A
Authority
GB
United Kingdom
Prior art keywords
stage
varied
transistor
input
signal current
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
GB35025/58A
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.)
Philips Electrical Industries Ltd
Original Assignee
Philips Electrical Industries 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 Philips Electrical Industries Ltd filed Critical Philips Electrical Industries Ltd
Publication of GB892921A publication Critical patent/GB892921A/en
Expired legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03G—CONTROL OF AMPLIFICATION
    • H03G3/00—Gain control in amplifiers or frequency changers
    • H03G3/02—Manually-operated control
    • H03G3/04—Manually-operated control in untuned amplifiers
    • H03G3/10—Manually-operated control in untuned amplifiers having semiconductor devices

Landscapes

  • Tone Control, Compression And Expansion, Limiting Amplitude (AREA)

Abstract

892,921. Transistor amplifying circuits. PHILIPS ELECTRICAL INDUSTRIES Ltd. Oct. 31, 1958 [Nov. 4, 1957], No. 35025/58. Class 40(6). In a transistor amplifier a source of signals is connected to the input electrodes of two transistors, the part of the signal current flowing to one transistor being varied by controlling the input base-emitter impedance of the other. Microphone 1, Fig. 1, feeds a lowfrequency amplifier comprising R.C. coupled stages 2, 3 and output stage 4 driving loudspeaker 5. A further amplifier stage 8, fed in parallel with the stage 4 provides A.G.C., its output being rectified by diode 9 and applied via smoothing network 10, 11 to control the gain of the input stage 2. The input impedance of transistor 4 is varied by means of resistors 6, 17, the variable resistor 6 being shunted for signal frequencies by condenser 7 and constituting the volume control: the volume is varied by controlling the signal current into the stage 4 feeding the A.G.C. circuit. In another embodiment, the input impedance of output stage 4, Fig. 2, is varied by means. of a variable base bias resistor 21 and controls the signal current returned to preceding stage 2, via resistor 20 as negative feedback.
GB35025/58A 1957-11-04 1958-10-31 Improvements in transistor amplifiers Expired GB892921A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
NL892921X 1957-11-04

Publications (1)

Publication Number Publication Date
GB892921A true GB892921A (en) 1962-04-04

Family

ID=19855983

Family Applications (1)

Application Number Title Priority Date Filing Date
GB35025/58A Expired GB892921A (en) 1957-11-04 1958-10-31 Improvements in transistor amplifiers

Country Status (1)

Country Link
GB (1) GB892921A (en)

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