CN203054095U - Input circuit used for measuring conductance of liquid - Google Patents
Input circuit used for measuring conductance of liquid Download PDFInfo
- Publication number
- CN203054095U CN203054095U CN 201220698433 CN201220698433U CN203054095U CN 203054095 U CN203054095 U CN 203054095U CN 201220698433 CN201220698433 CN 201220698433 CN 201220698433 U CN201220698433 U CN 201220698433U CN 203054095 U CN203054095 U CN 203054095U
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- Prior art keywords
- circuit
- conductance
- liquid
- operational amplifier
- input circuit
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- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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- Measurement Of Resistance Or Impedance (AREA)
- Investigating Or Analyzing Materials By The Use Of Electric Means (AREA)
Abstract
The utility model discloses an input circuit used for measuring conductance of liquid. The input circuit comprises an operational amplifier. A non-inverting input end of the operational amplifier is connected with a sine wave oscillator, and an inverting input end of the operational amplifier is connected with a conductance measuring electrode. A resistor is in bridge connection between an output end and a reverse input end of the operation amplifier. The beneficial effects are that the circuit of the utility model is simple and cheap and is easy to realize; and an output voltage signal of the circuit is in a linear relation with a conductance value to be measured, and the conductance value can be measured accurately and reliably after the output voltage signal of the circuit is sent to a subsequent rectification circuit, a filter circuit, an amplification circuit, an A/D and a single-chip microcomputer circuit.
Description
Technical field
The utility model relates to a kind of for the input circuit of measuring conductance of liquid, belongs to the surveying instrument technical field.
Background technology
Conductance of liquid is as a kind of important electrochemical analysis parameter, and it measures the fields such as chemical industry, metallurgy, biology, medical science, grain, water conservancy, environmental protection, the energy that have been widely used in.Yet the input circuit part of conductivity meter all adopts the principle of balance bridge design at present, but there are shortcomings such as complex structure, nonlinearity erron in null-type bridge circuit, and there are shortcomings such as accuracy is low, use inconvenience in the conductivity meter of making thus.
Summary of the invention
The technical matters that the utility model solves provides a kind of linearity, simple, accurate, the reliable input circuit that is used for measuring conductance of liquid.
It is a kind of for the input circuit of measuring conductance of liquid that the utility model provides, it is characterized in that this input circuit comprises operational amplifier, the in-phase input end of this operational amplifier connects sine-wave oscillator, inverting input connects the conductance measurement electrode, and resistance is connected across between the output terminal and reverse input end of amplifier.
Described sine-wave oscillator adopts RC bridge-type sine-wave oscillator.
Adopt the utility model beneficial effect to be: this circuit not only simple, cheap, be easy to realize, and the output voltage signal of this circuit and electric conductivity value to be measured have linear relationship, the output voltage signal of this circuit is delivered to follow-up rectification, filtering, amplification, A/D, single chip circuit, can record electric conductivity value accurately and reliably.
Description of drawings
Fig. 1 is a kind of for the input circuit figure that measures conductance of liquid for the present invention.
Embodiment
The present invention is specifically introduced as follows below in conjunction with drawings and Examples:
The utility model is described a kind of for the input circuit of measuring conductance of liquid, comprise operational amplifier U1, and the in-phase input end (+) of operational amplifier U1 connects the RC oscillator, inverting input (-) connects the conductance measurement electrode, resistance is connected across between the output terminal Uo and reverse input end (-) of amplifier, and namely this amplifier is formed the in-phase proportion amplifying circuit.
That is, amplifier in-phase end (+) connects the RC oscillator, namely inserts sine wave signal ui, and inverting input (-) connects the conductance measurement electrode, namely inserts measuring resistance Rx to be measured, and its inverse is then led Gx for electricity to be measured, and feedback resistance is Rf, then
Because ui is stable signal, i.e. constant.Can draw according to following formula, Uo and Gx are linear, and the output voltage signal of this circuit is delivered to follow-up rectification, filtering, amplification, A/D, single chip circuit, can record electric conductivity value accurately and reliably.
Below announced the present invention with preferred embodiment, so it is not in order to limiting the present invention, all take to be equal to replace or technical scheme that the form of equivalent transformation obtains, all drop within protection scope of the present invention.
Claims (2)
1. input circuit of be used for measuring conductance of liquid, it is characterized in that this input circuit comprises operational amplifier, the in-phase input end of this operational amplifier connects sine-wave oscillator, and inverting input connects the conductance measurement electrode, and resistance is connected across between the output terminal and reverse input end of amplifier.
2. according to claim 1 a kind of for the input circuit of measuring conductance of liquid, it is characterized in that described sine-wave oscillator adopts RC bridge-type sine-wave oscillator.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 201220698433 CN203054095U (en) | 2012-12-11 | 2012-12-11 | Input circuit used for measuring conductance of liquid |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 201220698433 CN203054095U (en) | 2012-12-11 | 2012-12-11 | Input circuit used for measuring conductance of liquid |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN203054095U true CN203054095U (en) | 2013-07-10 |
Family
ID=48737035
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 201220698433 Expired - Fee Related CN203054095U (en) | 2012-12-11 | 2012-12-11 | Input circuit used for measuring conductance of liquid |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN203054095U (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103048546A (en) * | 2012-12-11 | 2013-04-17 | 南京化工职业技术学院 | Input circuit for measuring liquid electricity conductivity |
-
2012
- 2012-12-11 CN CN 201220698433 patent/CN203054095U/en not_active Expired - Fee Related
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103048546A (en) * | 2012-12-11 | 2013-04-17 | 南京化工职业技术学院 | Input circuit for measuring liquid electricity conductivity |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20130710 Termination date: 20141211 |
|
| EXPY | Termination of patent right or utility model |