Patent US2947432A successfully refreshed from Google Patents.
Patent US4138639A successfully refreshed from Google Patents.
US4138639A
Expired / Lapsed
US
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Fluid conductivity measurement
Assignee: Individual
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Filing: 1977-07-14
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Granted: 1979-02-06
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Expires: 1997-07-14
Abstract
Abstract Fluid conductivity measuring apparatus employing fluid-coupled primary and secondary transformer windings where the primary transformer winding is energized by an oscillator. Accuracy in the apparatus is enhanced through the use therein of a feedback winding in the primary section of the transformer which couples with an output-level-control input in the oscillator to inhibit any tendency of the signal output level of the oscillator to change.
Inventors
- 👤 Thomas B. Hutchins
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 22:24
CPC Classifications
G; G01; G01R; G01R27/00; G01R27/02; G01R27/22; G01N; G01N27/00; G01N27/02; G01N27/023
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
135 words
Electrical apparatus with feedback stabilization for measuring the conductivity of a fluid comprising spaced primary and secondary transformer winding means, fluid conduit means, for containing a fluid whose conductivity is to be measured, electrically coupling said winding means, output-level-controllable oscillator means connected to energize said primary winding means and including an output-level-control input, feedback means operatively coupling said primary winding means and said input, operable, with said oscillator means oscillating, and in cooperation with said input and said primary means, to inhibit any tendency of the output level of the oscillator means to change, and signal output means operatively connected to said secondary winding means, constructed, with said apparatus functioning, to produce an output signal having an electrical characteristic which is directly relatable to the conductivity of any fluid contained in said fluid conduit means.
Claim 2
Dependent Claim
135 words
Electrical apparatus with feedback stabilization for measuring the conductivity of a fluid comprising spaced primary and secondary transformer winding means, fluid conduit means, for containing a fluid whose conductivity is to be measured, electrically coupling said winding means, output-level-controllable oscillator means connected to energize said primary winding means and including an output-level-control input, feedback means operatively coupling said primary winding means and said input, operable, with said oscillator means oscillating, and in cooperation with said input and said primary means, to inhibit any tendency of the output level of the oscillator means to change, and signal output means operatively connected to said secondary winding means, constructed, with said apparatus functioning, to produce an output signal having an electrical characteristic which is directly relatable to the conductivity of any fluid contained in said fluid conduit means.
Claim 3
Dependent Claim
14 words
The apparatus of claim 1, wherein said signal output means includes a zero-input-impedancy amplifier.
References Cited (Backward Citations)
US3054946A
Cited
US3404336A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1982-02-05 | 1982-08-07 | 1983-02-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1986-02-05 | 1986-08-07 | 1987-02-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1990-02-05 | 1990-08-07 | 1991-02-06 | $7700.00 | Window Closed / Lapsed |