US3725583A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Volume and tone control for multi-channel audio systems
Assignee: Motorola Solutions Inc
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Filing: 1970-07-20
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Granted: 1973-04-03
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Expires: 1990-07-20
Abstract
Abstract A single volume control for a plurality of audio channels is formed by a pair of gain controllable differential amplifiers operated as small-signal amplifiers in an open-ended configuration. The current source for each differential amplifier is provided by a variable current source, such as a transistor collector. By altering the DC bias on this variable current source transistor, the bias current and therefore the gain of the differential amplifier is correspondingly varied. A single potentiometer provides the DC voltage control for the variable current source transistors which, in turn, function as a volume control for the circuit.
Inventors
- 👤 P Gunderson
- 👤 R Freimark
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 14:52
CPC Classifications
H; H03; H03G; H03G1/00; H03G1/0005; H03G1/0035; H03G1/0082; H03F; H03F3/00; H03F3/68; H03G1/0017; H03G1/0023; H03G3/00; H03G3/02; H03G3/04; H03G3/10
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
246 words
In an audio system having at least two channels for translating audio signals therethrough to speaker output means, the combination including, a volume control circuit in each channel of the audio system, each said volume control circuit being responsive to a varying direct current bias to control the gain of the audio signal in each channel, a first variable resistance element coupled between a source of direct current voltage and respective ones of said volume control circuits, whereby operation of said first variable resistance element varies the direct current bias simultaneously to each said volume control circuit to vary the gain of the audio signal in each channel, a tone control circuit in each channel of the audio system, each said tone control circuit being responsive to a varying direct current bias to control the tone of the audio signal in each channel, a second variable resistance element coupled between a source of direct current voltage and respective ones of said tone control circuits, whereby operation of said second variable resistance element varies the direct current bias simultaneously to each said tone control circuit to vary the tone of the audio signal in each channel, and resistance means connecting said second variable resistance element to said first variable resistance element whereby operation of said second variable resistance element to change the tone of the audio signal in each channel simultaneously varies the bias from said first variable resistance element to change the volume in each channel.
Claim 2
Dependent Claim
246 words
In an audio system having at least two channels for translating audio signals therethrough to speaker output means, the combination including, a volume control circuit in each channel of the audio system, each said volume control circuit being responsive to a varying direct current bias to control the gain of the audio signal in each channel, a first variable resistance element coupled between a source of direct current voltage and respective ones of said volume control circuits, whereby operation of said first variable resistance element varies the direct current bias simultaneously to each said volume control circuit to vary the gain of the audio signal in each channel, a tone control circuit in each channel of the audio system, each said tone control circuit being responsive to a varying direct current bias to control the tone of the audio signal in each channel, a second variable resistance element coupled between a source of direct current voltage and respective ones of said tone control circuits, whereby operation of said second variable resistance element varies the direct current bias simultaneously to each said tone control circuit to vary the tone of the audio signal in each channel, and resistance means connecting said second variable resistance element to said first variable resistance element whereby operation of said second variable resistance element to change the tone of the audio signal in each channel simultaneously varies the bias from said first variable resistance element to change the volume in each channel.
Claim 3
Dependent Claim
93 words
The audio system of claim 1 wherein said volume control circuit includes differential amplifier means and an electron control device having a first electrode coupled to said differential amplifier means, a second electrode coupled to a reference potential and a control electrode, said differential amplifier means having input means for receiving audio signal information and output means for translating the audio signal information to the speaker output means, said first variable resistance element coupled between said source of direct current voltage and the respective control electrodes of each of said current control devices.
Claim 4
Dependent Claim
83 words
The audio system of claim 2 wherein each said tone control circuit includes high frequency shunting circuit means connected to the input of each differential amplifier means, said high frequency shunting circuit means being responsive to a bias voltage being applied thereto to provide a tone control in each of the channels, said second variable resistance element coupled between each high frequency shunting circuit means and said source of direct current voltage for applying a varying bias thereto to effect the tone control.
Claim 5
Dependent Claim
33 words
The audio system of claim 2 further including a third variable resistance element connected between said output means of each said differential amplifier means to provide a balance control between the two channels.
Claim 6
Dependent Claim
69 words
The audio system of claim 3 wherein said high frequency shunting circuit means includes a semiconductor having input, output and control electrodes, and a capacitor, said capacitor being connected between said input of said differential amplifier means and said input electrode of said semiconductor, said output electrode of said semiconductor being connected to a reference potential, and said control electrode thereof being connected to said second variable resistance element.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-04-02 | 1976-10-02 | 1977-04-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-04-02 | 1980-10-02 | 1981-04-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-04-02 | 1984-10-02 | 1985-04-03 | $7700.00 | Window Closed / Lapsed |