US3983512A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Current controlled electrical circuits
Assignee: Feedback Instruments Ltd
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Filing: 1975-08-22
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Granted: 1976-09-28
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Expires: 1995-08-22
Abstract
Abstract A resonant circuit is provided with a number of phase shift circuits connected in series. A control circuit is connected in series with the phase shift circuits for controlling the direct current flowing through the circuits. One of the phase shift circuits is constructed of a pair of transistors interconnected by a capacitor. The emitter resistance of the transistors is determined by the direct currents flowing therethrough from the control circuit, whereupon the frequency of oscillation or resonance of the resonant circuit is dependant upon the emitter resistance.
Inventors
- 👤 William Mark Lipscombe
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 23:19
CPC Classifications
H; H03; H03B; H03B5/00; H03B5/20; H03B5/24; H03B27/00
Claims Analysis
Total Claims: 19
Claim 1
Independent Claim
81 words
A resonant circuit including a plurality of balanced phase shift circuits connected in series, a pair of transistors interconnected by a capacitor defining one of said phase shift circuits, and control means connected in series with the phase shift circuits for supplying balanced direct currents to the balanced phase shift circuits, wherein the control means is effective to define the direct current flowing through the transistors, the emitter resistance of the transistors and hence the frequency of oscillation of the circuit.
Claim 2
Dependent Claim
81 words
A resonant circuit including a plurality of balanced phase shift circuits connected in series, a pair of transistors interconnected by a capacitor defining one of said phase shift circuits, and control means connected in series with the phase shift circuits for supplying balanced direct currents to the balanced phase shift circuits, wherein the control means is effective to define the direct current flowing through the transistors, the emitter resistance of the transistors and hence the frequency of oscillation of the circuit.
Claim 3
Dependent Claim
26 words
A circuit according to claim 1, including an amplifier and three series connected balanced phase shift circuits interconnected between the input and output of the amplifier.
Claim 4
Dependent Claim
44 words
A circuit according to claim 2, wherein the control means is connected in series with the phase shift circuits between terminals connectible to a voltage source, at least two of the phase shift circuits each comprising a pair of transistors interconnected by a capacitor.
Claim 5
Dependent Claim
40 words
A circuit according to claim 2, including a pair of drive transistors connected by their base electrodes to the amplifier, the emitter electrodes of said drive transistors being interconnected with each other and together further connected with the control means.
Claim 6
Dependent Claim
36 words
A circuit according to claim 4, wherein the capacitor of a first phase shift circuit is connected between the collector electrodes of the pair of drive transistors and the emitters of a second pair of transistors.
Claim 7
Dependent Claim
58 words
A circuit according to claim 5, wherein a second phase shift circuit constituted by a third pair of transistors and a second capacitor, is connected by the emitter electrodes of the third transistors to respective collector electrodes of the second pair of transistors, the second capacitor being connected between the emitter electrodes of the third pair of transistors.
Claim 8
Dependent Claim
56 words
A circuit according to claim 6, wherein a third phase shift circuit, constituted by a fourth pair of transistors and a third capacitor, is connected to the second phase shift circuit in the same manner as the second circuit is connected to the first circuit, the input to the amplifier being connected across the third capacitor.
Claim 9
Dependent Claim
75 words
A resonant circuit including a plurality of balanced phase shift circuits connected in series, a pair of transistors interconnected by a capacitor defining one of said phase shift circuits, and control means connected in series with the phase shift circuits for supplying balanced direct currents to the balanced phase shift circuits, wherein the control means is effective to define the direct current flowing through the transistors and hence the frequency at which the circuit resonates.
Claim 10
Dependent Claim
75 words
A resonant circuit including a plurality of balanced phase shift circuits connected in series, a pair of transistors interconnected by a capacitor defining one of said phase shift circuits, and control means connected in series with the phase shift circuits for supplying balanced direct currents to the balanced phase shift circuits, wherein the control means is effective to define the direct current flowing through the transistors and hence the frequency at which the circuit resonates.
Claim 11
Dependent Claim
33 words
A circuit according to claim 8, including two phase shift circuits a first one of the phase shift circuits constituting a phase advance circuit and a second one constituting a phase retard circuit.
Claim 12
Dependent Claim
25 words
A circuit according to claim 8, wherein the two phase shift circuits each comprise a capacitor connected between the emitters of a pair of transistors.
Claim 13
Dependent Claim
36 words
A circuit according to claim 10, wherein a first pair of transistors associated with the first phase shift circuit have their collectors interconnected to the bases of the opposite transistor of said first pair of transistors.
Claim 14
Dependent Claim
31 words
A circuit according to claim 8, wherein the phase retard circuit comprises a balanced pair of series connected transistors, the base of each individual transistor being connected with the collector thereof.
Claim 15
Dependent Claim
23 words
A circuit according to claim 9, wherein the phase retard circuit comprises a balanced pair of series connected diodes interconnected by a capacitor.
Claim 16
Dependent Claim
13 words
A circuit according to claim 8, including two resonant circuits connected in series.
Claim 17
Dependent Claim
14 words
A circuit according to claim 8, wherein the control means comprises a variable resistor.
Claim 18
Dependent Claim
14 words
A circuit according to claim 8, wherein the control means comprises a control circuit.
Claim 19
Dependent Claim
45 words
A circuit according to claim 16, wherein the control circuit comprises a pair of balanced transistors arranged to be connected via their base circuits with a direct current source and via their collector circuits with the direct current inputs to a first phase shift circuit.
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) | 1979-09-28 | 1980-03-29 | 1980-09-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-09-28 | 1984-03-29 | 1984-09-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-09-28 | 1988-03-29 | 1988-09-28 | $7700.00 | Window Closed / Lapsed |