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Patent US3831083A successfully refreshed from Google Patents.
US3831083A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Conductivity and specific resistance measuring system
Assignee: MC NAB Inc
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Filing: 1973-02-12
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Granted: 1974-08-20
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Expires: 1993-02-12
Abstract
Abstract Apparatus for monitoring the conductivity or specific resistance of solutions over a broad range consisting of an electronic circuit including a conductivity cell which is adapted to be immersed in the solution and through which AC current is passed. Through the use of a switching arrangement, the same circuit design is useful to measure both conductivity and specific resistance of solutions. The cell output is fed to an operational differential integrated amplifier which is used to drive the meter and recorder components. The cell output is also compared to a reference voltage by a controller section and, when the cell signal exceeds a predetermined level, warning signals are produced. The unit is capable of generating an alarm signal upon the occurrence of two or more alarm points being exceeded.
Inventors
- 👤 H Teass
- 👤 Veniz W Smith
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 18:10
CPC Classifications
G; G01; G01N; G01N27/00; G01N27/02; G01N27/04; G01N27/06
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
201 words
An electric system for monitoring the conductivity of a liquid, said system comprising: a. an electrical circuit for generating a regulated DC voltage; b. an electrical circuit for generating a regulated AC voltage; c. a conductivity cell in contact with said liquid, said cell being connected to said AC source; d. a temperature responsive network in series circuit with said cell and in thermal proximity to said liquid; e. an indicating circuit for indicating the peak value of any current flow through said cell; f. a first amplifier connected to receive any current output from said cell and to drive said indicating circuit; g. a second amplifier adapted to receive a positive DC output from said first amplifier as one input thereto, to receive a negative reference DC input derived from said regulated DC voltage as a second input thereto, and producing an output signal; and, h. a variable hysteresis circuit, including said second amplifier having input terminals, means in said circuit for maintaining the amplifier in the positive state when the amplifier senses that the input on one terminal is more positive than on the other, whereby a change of hysteresis does not change the trigger point of the unit.
Claim 2
Dependent Claim
201 words
An electric system for monitoring the conductivity of a liquid, said system comprising: a. an electrical circuit for generating a regulated DC voltage; b. an electrical circuit for generating a regulated AC voltage; c. a conductivity cell in contact with said liquid, said cell being connected to said AC source; d. a temperature responsive network in series circuit with said cell and in thermal proximity to said liquid; e. an indicating circuit for indicating the peak value of any current flow through said cell; f. a first amplifier connected to receive any current output from said cell and to drive said indicating circuit; g. a second amplifier adapted to receive a positive DC output from said first amplifier as one input thereto, to receive a negative reference DC input derived from said regulated DC voltage as a second input thereto, and producing an output signal; and, h. a variable hysteresis circuit, including said second amplifier having input terminals, means in said circuit for maintaining the amplifier in the positive state when the amplifier senses that the input on one terminal is more positive than on the other, whereby a change of hysteresis does not change the trigger point of the unit.
Claim 3
Dependent Claim
43 words
The system according to claim 1 wherein said regulated DC voltage generating circuit includes a zener diode and a capacitor connected in parallel with an output terminal thereof, whereby said capacitor functions to provide additional DC power when the dynamic load requires it.
Claim 4
Dependent Claim
72 words
The system according to claim 1 wherein the circuit including said conductivity cell, said thermal network and said AC regulated source further comprises first and second switches, each having first and second states, whereby when said switches are in said first state said indicating circuit will indicate the conductivity of said liquid and when said switches are in said second state said indicating circuit will indicate the specific resistance of said liquid.
Claim 5
Dependent Claim
16 words
The system according to claim 1 wherein said indicating circuit comprises a meter and a recorder.
Claim 6
Dependent Claim
37 words
The system according to claim 1 wherein said first and second amplifiers comprise differential, operational integrated circuit amplifiers and a diode is positioned between the output of said first amplifier and an input of said second amplifier.
Claim 7
Dependent Claim
25 words
The system according to claim 1 further comprising an RC integrating network connected in circuit between said first amplifier output and said second amplifier input.
Claim 8
Dependent Claim
23 words
The system according to claim 1 further comprising a closed positive feedback loop connecting said second amplifier output to said second amplifier input.
Claim 9
Dependent Claim
36 words
The system according to claim 7 further comprising a transistor adapted to receive and be turned on by an output from said second amplifier and a relay adapted to be actuated by conductance of said transistor.
Claim 10
Dependent Claim
36 words
The system of claim 8 further comprising a secoNd RC integrating network connected between said second amplifier output and said transistor whereby said second RC network supplies said closed positive feedback loop and said transistor input.
Claim 11
Dependent Claim
29 words
The system according to claim 1 further comprising means adapted to receive said first amplifier output for generating a control output signal when said second amplifier produces an output.
References Cited (Backward Citations)
US3430129A
Cited
US3582767A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-08-19 | 1978-02-18 | 1978-08-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-08-19 | 1982-02-18 | 1982-08-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-08-19 | 1986-02-18 | 1986-08-20 | $7700.00 | Window Closed / Lapsed |