Patent US4223273A successfully refreshed from Google Patents.
US4223273A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Power amplifying device for driving loudspeakers
Assignee: Nippon Gakki Co Ltd
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Filing: 1978-11-03
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Granted: 1980-09-16
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Expires: 1998-11-03
Abstract
Abstract A power amplifier device comprising first and second output terminals connected to a loudspeaker, and a power amplifier having a non-inverting input supplied with an audio signal, an output connected to the first output terminal and an inverting input. The second output terminal is grounded through a first resistor and connected to an input of an inverting amplifier having a gain of -1. An output of the inverting amplifier is connected to the inverting input of the power amplifier through a second resistor. The output of the power amplifier is connected to its inverting input through a third resistor. The ratio of the third resistor to the second resistor is selected to be larger than 1 whereby the output impedance of the power amplifier device as seen from the first and second output terminals is made to be negative.
Inventors
- 👤 Kenji Yokoyama
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 21:51
CPC Classifications
H; H03; H03F; H03F1/00; H03F1/34; H03F1/56; H03F3/00; H03F3/20
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
205 words
A power amplifying device comprising: power amplifier means having a noninverting input, an inverting input and an output; a first output terminal connected to said output of said power amplifier means; a second output terminal; said first and second output terminals being connected to a loudspeaker through a line; means for applying an input signal to said noninverting input of said power amplifier means; and current feedback means connected between said second output terminal and said inverting input of said power amplifier means, said current feedback means comprising a first resistor having one end connected to said second output terminal and the other end grounded, inverting amplifier means having an input connected to said second output terminal, and a potentiometer having one fixed end coupled to said second output terminal, the other fixed end coupled to an output of said inverting amplifier means and a slidable contact coupled to said inverting input of said power amplifier means, said potentiometer used to selectively cause the polarity of the feedback of said feedback means to be either negative or positive so as to thereby vary the output impedance of said power amplifier device over positive and negative ranges as seen from said first and second output terminals.
Claim 2
Dependent Claim
205 words
A power amplifying device comprising: power amplifier means having a noninverting input, an inverting input and an output; a first output terminal connected to said output of said power amplifier means; a second output terminal; said first and second output terminals being connected to a loudspeaker through a line; means for applying an input signal to said noninverting input of said power amplifier means; and current feedback means connected between said second output terminal and said inverting input of said power amplifier means, said current feedback means comprising a first resistor having one end connected to said second output terminal and the other end grounded, inverting amplifier means having an input connected to said second output terminal, and a potentiometer having one fixed end coupled to said second output terminal, the other fixed end coupled to an output of said inverting amplifier means and a slidable contact coupled to said inverting input of said power amplifier means, said potentiometer used to selectively cause the polarity of the feedback of said feedback means to be either negative or positive so as to thereby vary the output impedance of said power amplifier device over positive and negative ranges as seen from said first and second output terminals.
Claim 3
Dependent Claim
33 words
A power amplifying device according to claim 1 wherein said current feedback means further comprises a resistor connected between said output of said power amplifier means and said slidable contact of said potentiometer.
Claim 4
Dependent Claim
48 words
A power amplifying device according to claim 2 wherein said current feedback means further comprises variable resistors respectively connected between said one fixed end of said potentiometer and the output of said inverting amplifier and between said other fixed end of said potentiometer and said second output terminal.
Claim 5
Dependent Claim
33 words
A power amplifying device according to claim 1 wherein said current feedback further comprises a resistor connected between said output of said power amplifier means and the other fixed end of said potentiometer.
Claim 6
Dependent Claim
122 words
A power amplifying device according to claim 1 wherein said inverting amplifier means comprises an operational amplifier having a grounded noninverting input, an inverting input and an output, and wherein said current feedback means further comprises: a second resistor connected between said second output terminal and the inverting input of said operational amplifier; a third resistor connected between the inverting input and the output of said operational amplifier; a fourth resistor connected between the output of said operational amplifier and the other fixed end of said potentiometer; and a fifth resistor connected between said other fixed end of said potentiometer and the output of said power amplifier means whereby said output impedance is varied between a positive value and a negative value.
References Cited (Backward Citations)
US3525812A
Cited
US4092494A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1983-09-16 | 1984-03-17 | 1984-09-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1987-09-16 | 1988-03-17 | 1988-09-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1991-09-16 | 1992-03-17 | 1992-09-16 | $7700.00 | Window Closed / Lapsed |