US4002994A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Tone control circuit
Assignee: Individual
•
Filing: 1976-01-26
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Granted: 1977-01-11
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Expires: 1996-01-26
Abstract
Abstract A tone control circuit comprising an operational amplifier having an input and an output and a negative feedback circuit connected between the output and the input, the feedback circuit including a plurality of resistors and capacitors for controlling the magnitude of the high and low frequency components fed back to the input of the operational amplifier to selectably provide low frequency boost and high frequency boost or cut, the circuit having a high input impedance, a low output impedance, gain, and a relatively constant phase shift.
Inventors
- 👤 C. Leo Fender
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 14:25
CPC Classifications
H; H03; H03G; H03G5/00; H03G5/02; H03G5/04; G; G10; G10H; G10H3/00; G10H3/12; G10H3/14; G10H3/18; G10H3/186
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
124 words
A tone control circuit comprising: an operational amplifier having an input and an output; and a negative feedback circuit connected between said output and said input, said feedback circuit comprising: a first variable resistor, a second resistor having a manually movable tap, and a third resistor connected in series between said output and said input; a first capacitor connected across said first resistor; a fourth resistor connected between a first junction between said first and second resistors and ground; a fifth resistor and a second capacitor connected in series between said manually movable tap of said second resistor and ground; and a third capacitor connected between said manually movable tap of said second resistor and a second junction between said second and third resistors.
Claim 2
Dependent Claim
124 words
A tone control circuit comprising: an operational amplifier having an input and an output; and a negative feedback circuit connected between said output and said input, said feedback circuit comprising: a first variable resistor, a second resistor having a manually movable tap, and a third resistor connected in series between said output and said input; a first capacitor connected across said first resistor; a fourth resistor connected between a first junction between said first and second resistors and ground; a fifth resistor and a second capacitor connected in series between said manually movable tap of said second resistor and ground; and a third capacitor connected between said manually movable tap of said second resistor and a second junction between said second and third resistors.
Claim 3
Dependent Claim
52 words
A tone control circuit according to claim 1 wherein movement of said movable tap of said second resistor towards said second junction increases the high frequency boost of said circuit and movement of said movable tap of said second resistor towards said first junction increases the high frequency cut of said circuit.
Claim 4
Dependent Claim
27 words
A tone control circuit according to claim 2 wherein maximum high frequency boost occurs when said movable tap of said second resistor is at said second junction.
Claim 5
Dependent Claim
38 words
A tone control circuit according to claim 3 wherein the break point of said maximum high frequency boost occurs when the series impedance of said fifth resistor and said second capacitor equals the resistance of said second resistor.
Claim 6
Dependent Claim
27 words
A tone control circuit according to claim 4 wherein maximum high frequency cut occurs when said movable tap of said second resistor is at said first junction.
Claim 7
Dependent Claim
33 words
A tone control circuit according to claim 5 wherein the break point of said maximum high frequency cut occurs when the impedance of said third capacitor equals the resistance of said second resistor.
Claim 8
Dependent Claim
24 words
A tone control circuit according to claim 6 wherein increasing the value of said first resistor increases the low frequency boost of said circuit.
Claim 9
Dependent Claim
37 words
A tone control circuit according to claim 7 wherein the break point of said low frequency boost occurs when the parallel impedance of said first resistor and said first capacitor equals the resistance of said fourth resistor.
Claim 10
Dependent Claim
50 words
A tone control circuit according to claim 8 further comprising: a plurality of pick up coils; and relatively large value resistance connected in series with each pick up coil, all of said series connected coils and resistors being connected in parallel between said input of said operational amplifier and ground.
Claim 11
Dependent Claim
28 words
A tone control circuit according to claim 9 further comprising: a coupling capacitor connected between said series connected coils and resistors and said input of said operational amplifier.
Claim 12
Dependent Claim
24 words
A tone control circuit according to claim 1 wherein increasing the value of said first resistor increases the low frequency boost of said circuit.
Claim 13
Dependent Claim
37 words
A tone control circuit according to claim 11 wherein the break point of said low frequency boost occurs when the parallel impedance of said first resistor and said first capacitor equals the resistance of said fourth resistor.
Claim 14
Dependent Claim
50 words
A tone control circuit according to claim 1 further comprising: a plurality of pick up coils; and relatively large value resistance connected in series with each pick up coil, all of said series connected coils and resistors being connected in parallel between said input of said operational amplifier and ground.
Claim 15
Dependent Claim
28 words
A tone control circuit according to claim 13 further comprising: a coupling capacitor connected between said series connected coils and resistors and said input of said operational amplifier.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1980-01-11 | 1980-07-12 | 1981-01-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-01-11 | 1984-07-12 | 1985-01-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-01-11 | 1988-07-12 | 1989-01-11 | $7700.00 | Window Closed / Lapsed |