US3569603A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Moving formant band-pass amplifier for an electronic musical instrument
Assignee: Marmon Co
•
Filing: 1968-08-01
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Granted: 1971-03-09
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Expires: 1988-08-01
Abstract
Abstract A circuit for achieving the moving or changing formant effect in an electronic musical instrument such as an electric organ. The circuit employs a band-pass amplifier with parallel T resistivecapacitive feedback circuits in which an FET (Field Effect Transistor) is employed as a variable resistance to cut in, by degrees, one of the T feedback circuits. The effective resistance of the FET and thus the band-pass of the amplifier are varied by a capacitive and resistive timing circuit that is controlled via a keying circuit from one or more keys or other player-operated controls, such as the manual keys of an electric organ.
Inventors
- 👤 Donald R Kern
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 02:17
CPC Classifications
G; G10; G10H; G10H1/00; G10H1/02; G10H1/06; G10H1/14; G10L; G10L25/00; G10H2250/00; G10H2250/471; G10H2250/481; Y; Y10; Y10S; Y10S84/00; Y10S84/10
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
157 words
A musical instrument moving formant device comprising an audio frequency amplifier having a music signal input and an amplified output, means providing a feedback path connected for feeding back signal from said output to said input, said feedback path consisting of an RC, parallel T, frequency rejection circuit, one of the parallel branches of said circuit comprising a pair of resistors in series with a center connected capacitor and the other of the parallel branches comprising a pair of series connected capacitors with a center connected resistor, a voltage dependent variable impedance incorporated in one only of said branches and connected so that conduction throuGh the last said branch from said output to said input depends upon the voltage applied to said voltage dependent variable impedance, and means connected for applying a variable control voltage to said variable impedance to vary the conduction through one only of the parallel branches as a function of said control voltage.
Claim 2
Dependent Claim
157 words
A musical instrument moving formant device comprising an audio frequency amplifier having a music signal input and an amplified output, means providing a feedback path connected for feeding back signal from said output to said input, said feedback path consisting of an RC, parallel T, frequency rejection circuit, one of the parallel branches of said circuit comprising a pair of resistors in series with a center connected capacitor and the other of the parallel branches comprising a pair of series connected capacitors with a center connected resistor, a voltage dependent variable impedance incorporated in one only of said branches and connected so that conduction throuGh the last said branch from said output to said input depends upon the voltage applied to said voltage dependent variable impedance, and means connected for applying a variable control voltage to said variable impedance to vary the conduction through one only of the parallel branches as a function of said control voltage.
Claim 3
Dependent Claim
70 words
The moving formant device as called for in claim 1 in which the means for applying the variable control voltage comprises a timing circuit of the type for providing a gradual change of voltage for a few seconds followed by a steady voltage when activated and a rapid restoration of voltage to the original level when subsequently deactivated, and a manual control connected for activating and deactivating said timing circuit.
Claim 4
Dependent Claim
23 words
The moving formant device as called for in claim 1 in which the voltage dependent variable impedance device is a field effect transistor.
Claim 5
Dependent Claim
33 words
The moving formant device as called for in claim 1 in which the variable impedance device is incorporated in the branch which has the two capacitors in series and a center connected resistor.
Claim 6
Dependent Claim
43 words
The moving formant device as called for in claim 1 in which the rejection frequency of the parallel T circuit is lower when the impedance of said variable impedance is low than it is when the impedance of said variable impedance is high.
Claim 7
Dependent Claim
32 words
The moving formant device as called for in claim 5 in which the control voltage is applied to reduce the impedance of the variable impedance device for the duration of the voltage.
Claim 8
Dependent Claim
28 words
The moving formant device as called for in claim 1 in which the means for applying a variable control voltage is an oscillator operating at a vibrato frequency.
Claim 9
Dependent Claim
27 words
The moving formant device as called for in claim 2 in which the manual control is any of a group of playing keys of an electric organ.
Claim 10
Dependent Claim
72 words
The moving formant device as called for in claim 6 in which the means for applying the variable control voltage comprises a timing circuit of the type which provides a gradual voltage change as a function of time for a few seconds followed by a steady state voltage when actuated and a rapid restoration to the original state when subsequently deactivated, and manual means connected for activating and deactivating said timing circuit.
Claim 11
Dependent Claim
24 words
The moving formant device of claim 9 in which said manual means is any of a group of playing keys of an electric organ.
Claim 12
Dependent Claim
22 words
The moving formant device as called for in claim 9 in which the voltage dependent variable impedance is a field effect transistor.
References Cited (Backward Citations)
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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) | 1974-03-08 | 1974-09-07 | 1975-03-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-03-08 | 1978-09-07 | 1979-03-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-03-08 | 1982-09-07 | 1983-03-09 | $7700.00 | Window Closed / Lapsed |