US3783374A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Capacitance difference detector circuit
Assignee: Sundstrand Data Control Inc
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Filing: 1972-04-07
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Granted: 1974-01-01
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Expires: 1992-04-07
Abstract
Abstract A circuit for detecting or sensing the ratio of or unbalance between two impedance elements, as the sections of a differential capacitor in a servoed instrument. A source of alternating current has two outputs of opposite phase, one connected in each of a pair of circuits with the two impedance elements. A diode in each of the circuits is poled so that both circuits conduct during the same half cycle. A load connected with both circuits sums the opposite phase currents and the difference between the currents represents the ratio of the impedance elements.
Inventors
- 👤 M Eide
- 👤 D Clark
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 00:54
CPC Classifications
G; G01; G01R; G01R27/00; G01R27/02; G01R27/26; G01R27/2605; G01P; G01P15/00; G01P15/02; G01P15/08; G01P15/125; G01P2015/0805; G01P2015/0822; G01P2015/0825; G01P2015/0828
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
109 words
A circuit for detecting the difference of the values of two impedance elements, comprising: an alternating current source having two outputs of opposite phase; a pair of circuits, one connected with each of said source outputs; a current limiting impedance element in each circuit, at least one of the elements being variable; a pair of diodes, one in each circuit, poled to conduct opposite phase currents simultaneously during one half-cycle of the period of said alternating current source; and a common load connected with said circuits, said opposite phase currents being summed in said load, the load current magnitude representing the difference of the values of said impedance elements.
Claim 2
Dependent Claim
109 words
A circuit for detecting the difference of the values of two impedance elements, comprising: an alternating current source having two outputs of opposite phase; a pair of circuits, one connected with each of said source outputs; a current limiting impedance element in each circuit, at least one of the elements being variable; a pair of diodes, one in each circuit, poled to conduct opposite phase currents simultaneously during one half-cycle of the period of said alternating current source; and a common load connected with said circuits, said opposite phase currents being summed in said load, the load current magnitude representing the difference of the values of said impedance elements.
Claim 3
Dependent Claim
26 words
The detector circuit of claim 1 in which said alternating current source includes a transformer having two secondary windings, one providing each of the source outputs.
Claim 4
Dependent Claim
30 words
The detector circuit of claim 2 in which said transformer has a primary winding and the secondary windings are reversely wound, and physically balanced with respect to the primary winding.
Claim 5
Dependent Claim
55 words
The detector circuit of claim 1 in which said impedance elements are reactive, said detector circuit further including a second pair of diodes connected with said source and said impedance elements and conductive during the half-cycle of the period of said source opposite from said one half-Cycle during which current is conducted through said load.
Claim 6
Dependent Claim
14 words
The detector circuit of claim 4 in which said reactive impedance elements are capacitors.
Claim 7
Dependent Claim
18 words
The detector circuit of claim 5 in which said capacitors are the two sections of a differential capacitor.
Claim 8
Dependent Claim
43 words
The detector circuit of claim 6 in which the two sections of the differential capacitor are connected, one with each of the outputs of said source, said differential capacitor having a common terminal connected with said load to complete said pair of circuits.
Claim 9
Dependent Claim
68 words
The detector circuit of claim 1 in which said detector circuit further includes a second pair of diodes connected with said source and said impedance elements and conductive during the half-cycle of the period of said source opposite from said one half-cycle through which current is conducted during said load, a second load connected with said second pair of diodes, and an output circuit connected across both loads.
Claim 10
Dependent Claim
38 words
The detector circuit of claim 4 in which said load is resistive, the time constant of the circuit of each of the reactive impedance elements and said load being less than the period of said alternating current source.
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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) | 1976-12-31 | 1977-07-02 | 1978-01-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-12-31 | 1981-07-02 | 1982-01-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-12-31 | 1985-07-02 | 1986-01-01 | $7700.00 | Window Closed / Lapsed |