Patent US4259632A successfully refreshed from Google Patents.
US4259632A
Expired / Lapsed
US
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Continuous action capacitive moisture measuring apparatus
Assignee: OT TEHDAS Oy
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Filing: 1978-11-13
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Granted: 1981-03-31
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Expires: 1998-11-13
Abstract
Abstract Capacitive moisture measuring apparatus for continuously measuring the moisture content of granular material, such as grain, includes a series circuit including a measuring capacitor whose capacitance varies as a function of moisture content of granular material in which it is immersed during operation and a resistor coupled to the measuring capacitor, and an oscillator for generating a voltage signal of stable frequency and amplitude which is applied to the circuit. An operational amplifier is serially coupled to a diode to constitute an ideal diode, the latter being coupled across the measuring capacitor.
Inventors
- 👤 Ari J. Ahtiainen
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 16:47
CPC Classifications
G; G01; G01R; G01R27/00; G01R27/02; G01R27/26; G01R27/2605; G01N; G01N27/00; G01N27/02; G01N27/22; G01N27/223
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
102 words
Apparatus for measuring the moisture of granular material comprising: a series circuit including a measuring capacitor having a capacitance which varies as a function of moisture content, and a resistor coupled in series with said measuring capacitor; oscillator means for generating a voltage of substantially stable frequency and amplitude, said voltage being applied to said circuit; an operational amplifier serially coupled to a diode to constitute an ideal diode, the latter being coupled across said measuring capacitor; and an adjustable resistor coupled across said measuring capacitor whereby the resistance of said adjustable resistor is adjustable to calibrate the capacitance of said capacitor.
Claim 2
Dependent Claim
102 words
Apparatus for measuring the moisture of granular material comprising: a series circuit including a measuring capacitor having a capacitance which varies as a function of moisture content, and a resistor coupled in series with said measuring capacitor; oscillator means for generating a voltage of substantially stable frequency and amplitude, said voltage being applied to said circuit; an operational amplifier serially coupled to a diode to constitute an ideal diode, the latter being coupled across said measuring capacitor; and an adjustable resistor coupled across said measuring capacitor whereby the resistance of said adjustable resistor is adjustable to calibrate the capacitance of said capacitor.
Claim 3
Dependent Claim
23 words
Apparatus as recited in claim 1 wherein the frequency of the oscillator means is in the range of between 1 and 250 kHz.
Claim 4
Dependent Claim
17 words
Apparatus as recited in claim 2 wherein the frequency of the oscillator means is about 100 kHz.
Claim 5
Dependent Claim
16 words
Apparatus as recited in claim 1 wherein the capacitance of said capacitor is about 10 pF.
Claim 6
Dependent Claim
17 words
Apparatus as recited in claim 1 wherein the resistance of said resistor is about 150 k Ω.
References Cited (Backward Citations)
FR1253531A
Cited
US3508435A
Cited
US3641431A
Cited
US3626286A
Cited
US3651505A
Cited
US4013065A
Cited
US4122708A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1984-03-30 | 1984-09-29 | 1985-03-31 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-03-30 | 1988-09-29 | 1989-03-31 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-03-30 | 1992-09-29 | 1993-03-31 | $7700.00 | Window Closed / Lapsed |