Amplifiers – With semiconductor amplifying device – Including gain control means
Patent
1995-04-07
1996-08-06
Mullins, James B.
Amplifiers
With semiconductor amplifying device
Including gain control means
330 84, 330148, 330295, 381109, 381121, H03G 310, H03F 368
Patent
active
055437591
ABSTRACT:
An audio amplification circuit includes a ganged pair of logarithmic potentiometers, each potentiometer of the pair having an input terminal, an output terminal, and a wiper terminal. The input terminals of each potentiometer are adapted for connection to an audio input signal from an audio device such as a microphone. A preamplifier stage having an input is connected to the wiper terminals of both logarithmic potentiometers. An amplification stage has a matched pair of operational amplifiers with each operational amplifier having an input connected to the output of the preamplifier stage. Each operational amplifier has a feedback loop which includes the resistance of at least one of the logarithmic potentiometers between the output terminal and the wiper terminal of said logarithmic potentiometer. The outputs of the matched pair of operational amplifiers constitute the outputs of the amplification stage. The outputs may be daisy-chained together, and a floating output stage is also provided. The circuitry with certain modifications may also be used as an interface between an audio device such as a microphone and a recording device to bring all inputs to the proper level for the recording device.
REFERENCES:
patent: 3414830 (1968-12-01), Hellwarth
patent: 4396890 (1983-08-01), Kato et al.
Clarke, "Playmate 3W+3W Stereo Amplifier", Electronics Australia, Jan., 1980 pp. 52-59, vol. 41, No. 10.
Comeau, II Richard J.
Fay Richard
Digital Lab Studios, LLC
Horizon Music, Inc.
Mullins James B.
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