CN102866180A - High-precision intelligent acidity meter and measuring method thereof - Google Patents

Abstract

The invention discloses a high-precision intelligent acidity meter and a measuring method thereof. According to the invention, the A/D (analog/digital) switching circuit of the high-precision intelligent acidity meter comprises a temperature sensor, a PH sensor, a first operational amplifier, a second operational amplifier, a multichannel analog switch and an A/D converter, wherein the output ends of the temperature sensor and the PH sensor are respectively connected with a plurality of input ends of one channel of the multichannel analog switch through the first operational amplifier and the second operational amplifier; the multichannel analog switch is connected to the other channel of the multichannel analog switch; and the two output ends of the other channel are respectively connected with resistors in different resistance values. According to the measuring method, a calibration method for automatically identifying a standard liquid is adopted in the processes of one-point correction and two-point correction, and meanwhile, the PH values of the standard liquid and the measured liquid are calibrated by virtue of a temperature compensation method. According to the high-precision intelligent acidity meter and the measuring method thereof, the PH value of the calibrated standard solution can be automatically identified, and the PH value of the standard solution can be calibrated according to the ambient temperature, so that the manual operation is reduced and measuring precision of the PH value is greatly improved.

Description

High-precision intelligent acidometer and measuring method thereof

Technical field

The invention discloses a kind of high-precision intelligent acidity (PH) and take into account its measuring method, belong to the electronic measurement and control field.

Background technology

Along with the development of scientific research and the progress of production technology, the quantitative test of moisture has been listed in one of elementary item of all kinds of material physico-chemical analysis, as one of all kinds of materials important quality index, the significant data that its pH value is measured especially.In addition, in the production run or the measurement and the control that relate to liquid in the environmental protection, solid mixture pH value require also increasingly to increase, so also more and more universal as the use of analysis meter acidometer.Acidometer is called for short the PH meter, is comprised of electrode and metering circuit two parts.If can the Rational Maintenance electrode in the use, prepare standard buffer solution and proper operation electricity meter on request, can greatly reduce the PH error of indication, thereby improve chemical experiment, medical test the reliability of the data.

Existing PH meter adopts manual method to carry out verification mostly, and temperature compensation also is to adopt the mode of manual adjustments knob to carry out, and this method exists complex operation, the large and excessively low defective of precision affected by environment.Simultaneously, production run is very large with the maintenance workload of PH meter, the problem of zero point drift, range variation may often occur such as PH, and the workload of desk checking PH meter is larger, and affects the normal surveying work of PH meter.In order to overcome above defective, replace desk checking with automatic Verification, and increase the temperature automatic calibration function, be the development trend of intelligent PH meter.

The automatic check device development in recent years of PH meter is very fast, and its development is to be based upon on the basis of PH meter automatic flushing device, the online self-diagnostic function of sensor because will carry out automatic Verification, prerequisite be the cleaning of electrode and titer accurately.And sensor can provide basic data for the automatic Verification of PH meter.

Summary of the invention

Technical matters: existing PH meter, mostly adopt manual method to carry out verification, temperature compensation also is to adopt the mode of manual adjustments knob to carry out, this method exists complex operation, the large and excessively low defective of precision affected by environment.Simultaneously, production run is very large with the maintenance workload of PH meter, the problem of zero point drift, range variation may often occur such as PH, and the workload of desk checking PH meter is larger, and affects the normal surveying work of PH meter.

Usually, the concentration of standard solution all is the pH value that records under 25 ° of C environment temperatures, works as variation of ambient temperature, and the pH value of standard solution also changes thereupon to some extent; Most PH meter does not have the temperature correction function, has affected the measuring accuracy of pH value.

Simultaneously, for different standard solution and solution to be measured, the scope of the solution mV value of PH electrode output is larger, after the operational amplifier amplification, generally all 0～± 1999.9mV; Conventional PH meter all adopts same group of amplifying circuit to amplify, and has reduced resolution for some small-signals with the wide range conversion like this, has also affected the measuring accuracy of low concentration pH value.

In addition, the standard solution that is used for demarcating generally is about 3 kinds that fix, and the pH value that the PH meter must obtain these standard solution just can calculate; Conventional PH meter all is the pH value of manual input solution when proofreading and correct on one point with two point calibrations, and so not only inconvenience is used in operation, also may cause personal error.

Technical scheme: the object of the invention is to overcome the defects of conventional P H meter, propose a kind of high-precision intelligent acidity (PH) and take into account its measuring method, adopt following technical scheme:

A kind of high-precision intelligent acidometer, comprise single chip circuit, the A/D change-over circuit, man-machine interface circuit and power circuit, the A/D change-over circuit is connected with single chip circuit with the man-machine interface circuit and is connected, it is characterized in that, the A/D change-over circuit comprises temperature sensor, the PH sensor, the first operational amplifier, the second operational amplifier, multiway analog switch and A/D converter, temperature sensor, the output of PH sensor is respectively through first, the second operational amplifier is connected to a plurality of input ends of one of them passage of multiway analog switch, the output terminal of described one of them passage is connected with A/D converter, the output terminal of another passage of multiway analog switch is connected to the inverting input of the second operational amplifier, wherein two input ends of described another passage connect respectively the resistance of different resistances, switch for range, the address end of multiway analog switch is connected with single chip circuit.

The measuring method of described high-precision intelligent acidometer, it is characterized in that temperature compensation, adopt the temperature sensor measurement environment temperature, standard solution to non-standard temperature is proofreaied and correct, single chip circuit adopts different formulas to calculate according to different temperature ranges, obtain the pH value of the standard solution under the environment temperature, concrete grammar is as follows:

Some timings:

0°C～50°C PH ₁=0.0000483t ₁ ²-0.001266t ₁+4.004……（1）

50°C～60°C PH ₁=0.0000483t ₁ ²-0.001266t ₁+3.994……（2）

Wherein, PH ₁The measurement pH value that represents some calibration standard solution, t ₁Represent the ambient temperature value that a point calibration is measured;

During two point calibrations:

0°C～50°C PH ₂=0.00006875t ₂ ²-0.006311t ₂+6.979……（3）

50°C～60°C PH ₂＝0.0000776t ₂ ²-0.01268t ₂+9.453……（4）

Wherein, PH ₂The measurement pH value that represents two point calibration standard solution, t ₂Represent the ambient temperature value that two point calibrations are measured.

When carrying out a point calibration and two point calibrations, millivolt value according to the accurate solution of PH sensor institute's mark, after operational amplifier amplified, single chip circuit gathered the millivolt value after amplifying, and according to the automatic criterion of identification solution of millivolt value scope of various criterion solution.

Beneficial effect:

1, acidometer of the present invention adopts the automatic switchover of range, resistance with different resistances consists of two kinds of different feedback circuits, be connected with 2 input channels of multiway analog switch, single-chip microcomputer is by selecting the analog switch channel address, select corresponding passage, size according to the solution mV value of PH electrode output, realize range ability 0～± 399.9mV and 0～± automatically switch between the 1999.9mV, avoided small-signal wide range conversion (large scale of as the saying goes claims little thing), improve the resolution of small-signal, improved the measuring accuracy of low concentration solution.

2, acidometer of the present invention, multiway analog switch is connected in the feedback circuit of operational amplifier, the connection resistance of multiway analog switch has been eliminated resistance is connected in measured signal at analog switch loss as the part of operational amplifier feedback resistance, has improved measuring accuracy.

3, acidometer of the present invention adopts the temperature sensor measurement environment temperature, to proofreading and correct of the standard solution of non-standard temperature (25 ° of C), calculate with different formula according to different temperature ranges, obtain the pH value of the standard solution under the environment temperature, carry out temperature compensation with this, improved measuring accuracy.

4, acidometer of the present invention is when carrying out a point calibration and two point calibrations, millivolt (mV) value according to the standard solution that records, pH value or the concentration of automatic criterion of identification solution, need not to carry out manual input, reduced workload, the error of having avoided manually-operated to bring has improved automaticity.

5, acidometer of the present invention and measuring method thereof greatly improved the PH meter stability, can reach 0.001 measuring accuracy.

Description of drawings:

Fig. 1 is the structural drawing of patent high-precision intelligent acidity of the present invention (PH) meter.

Fig. 2 is the hardware circuit diagram of patent of the present invention.

Fig. 3 is the scope schematic diagram of the standard solution pH value of patent PH electrode output of the present invention.

Embodiment

Below in conjunction with accompanying drawing the present invention is done further and to elaborate:

Be illustrated in figure 1 as high-precision intelligent acidity of the present invention (PH) meter structural drawing, described PH meter comprises single chip circuit 1, A/D change-over circuit 2, power circuit 3, man-machine interface circuit 4.Power circuit 3 is respectively single chip circuit 1, A/D change- over circuit 2,4 power supplies of man-machine interface circuit.A/D change-over circuit 2 is connected with the man-machine interface circuit and is connected with single chip circuit 1 respectively.Single chip circuit 1 is take a single-chip microcomputer as core, in order to gather and computational data.Man-machine interface circuit 4 comprises LCD, keyboard and hummer, in order to show that input message is reported to the police.The A/D change-over circuit comprises temperature sensor (measurement temperature), PH sensor (measurement pH value), the first operational amplifier (output signal to temperature sensor is amplified), the second operational amplifier (output signal to the PH sensor is amplified), multiway analog switch (realizing the transmission of signal under the control of single-chip microcomputer) and A/D converter (be that digital signal for single-chip microcomputer processing with analog signal conversion).

The circuit diagram of high-precision intelligent acidity of the present invention (PH) meter as shown in Figure 2, the RS of LCD12864 in the man-machine interface circuit 4, R/W, the single-chip microcomputer U1(AT89C52 of E and single chip circuit 2) P1.3, P1.2, P1.1 connects, the port P0.0 of AT89C52, P0.1, P0.2, P0.3, P0.4, P0.5, P0.6, P0.7 be connected with P1.4 with man-machine interface circuit 4 in keyboard be connected the port P1.7 of the AT89C52 of single chip circuit 2 with hummer, P2.7, P2.6, P2.5, P2.4, P2.3, P2.2, P2.1, P2.0, P3.5, P3.4, A/D converter U8(7135 in P3.2 and P3.6 and the A/D change-over circuit 2) D1, D2, D3, D4, D5, B1, B2, B4, B8, POL, OR,-STB links to each other with R/-H.The clock circuit that also comprise by 555 in the A/D change-over circuit 2, capacitor C 9, C8 and slide rheostat R9, R12 forms.

Temperature sensor U9(AD590) signal output part is connected to the first operational amplifier M1(LM301) in-phase input end, the output terminal of the first operational amplifier M1 is connected to multiway analog switch U7(4052) the input end X3 of X passage.The signal output part of PH sensor U11 is connected to the second operational amplifier M2(LM301) in-phase input end, the output terminal of the second operational amplifier M2 is connected to input end X0 and the X1 of the X passage of multiway analog switch U7.The output terminal X of the X passage of multiway analog switch U7 be connected to 7135+IN ,-IN end, its output signal converts digital signal to through 7135 and processes for single-chip microcomputer.

The Y channel output end Y of multiway analog switch U7 is connected to the inverting input of the second operational amplifier M2.The Y passage input end Y0 of multiway analog switch U7 and Y1 connect respectively the resistance R 14(75K of different resistances) and R15(4.5K).Port P1.6 and P1.5 that the address end A of multiway analog switch U7, B connect respectively single-chip microcomputer, single-chip microcomputer is according to the size of the solution mV value of PH electrode output, the gating respective channel, make the connection resistance of resistance R 14 or R15 and multiway analog switch form series connection, feedback resistance as the second operational amplifier M2, can realize on the one hand range ability 0～± 399.9mV and 0～± automatically switch between the 1999.9mV, can also eliminate on the other hand measured signal and connect the loss of resistance at analog switch, improve measuring accuracy.

1, measuring method

1.1, preset

PH ₀=7.593 SLOPE ₀=0.19841t+54.195

PH ₀PH value, SLOPE are preset in expression ₀Slope is preset in expression.

1.2, a point calibration

Sampling mV ₁₀Show PH ₁₀=PH ₀-mV ₁₀/ Slope ₀

MV ₁₀The instantaneous millivolt of the measurement value that represents some calibration standard solution,

PH ₁₀The instantaneous pH value of measurement that represents some calibration standard solution.

Stable condition: begin timing 30s after pressing some check keys, require:

1. mV in first 10s behind the 30s ₁₀Variation is write down last mV less than 0.5mV if set up ₁₀Be worth, and turn steady state (SS), at this moment mV ₁=mV ₁₀

MV ₁The measurement millivolt value that represents some calibration standard solution.

If 2. first 10s does not surely get off, time-delay is judged by top method again, writes down last mV ₁₀Value, at this moment mV ₁=mV ₁₀

If 3. 30 " also stablely in do not get off, show error message

After stable, single-chip microcomputer is determined the final PH that shows according to environment temperature that temperature sensor is surveyed (being the temperature of the accurate solution of institute's mark) from following formula ₁Value:

0°C～50°C PH ₁=0.0000483t ₁ ²-0.001266t ₁+4.004……（1）

50°C～60°C PH ₁=0.0000483t ₁ ²-0.001266t ₁+3.994……（2）

(PH deposited in postscript ₁, mV ₁); t ₁

PH ₁The measurement pH value that represents some calibration standard solution,

t ₁Represent the ambient temperature value that a point calibration is measured.

1.3, two point calibrations

Sampling mV ₂₀Show PH ₂₀=PH ₀-mV ₂₀/ Slope ₀

MV ₂₀The instantaneous millivolt of the measurement value that represents two point calibration standard solution,

PH ₂₀The instantaneous pH value of measurement that represents two point calibration standard solution.

Stable condition: begin timing 30s after pressing two point calibration keys, require:

1. mV in first 10s behind the 30s ₂₀Variation is write down last mV less than 0.5mV if set up ₂₀Be worth, and turn steady state (SS), at this moment mV ₂=mV ₂₀

MV ₂The measurement millivolt value that represents two point calibration standard solution.

If 2. first 10s does not surely get off, time-delay is judged by top method again, writes down last mV ₁₀Value, at this moment mV ₂=mV ₂₀

If 3. 30 " also stablely in do not get off, show error message

After stable, single-chip microcomputer is determined the final PH that shows according to environment temperature that temperature sensor is surveyed (being the temperature of the accurate solution of institute's mark) from following formula ₂Value:

0°C～50°C PH ₂=0.00006875t ₂ ²-0.006311t ₂+6.979……（3）

50°C～60°C PH ₂=0.0000776t ₂ ²-0.01268t ₂+9.453……（4）

(PH deposited in stable postscript ₂, mV ₂); t ₂

PH ₂The measurement pH value that represents two point calibration standard solution,

t ₂Represent the ambient temperature value that two point calibrations are measured.

1.4, slope calculations

Slope $\mathrm{Slope}=\frac{m{V}_2-\mathrm{<figure-callout\; id="1"\; label="m\; V"\; filenames="HDA00002162506500011.png,HDA00002162506500021.png"\; state="\{\{state\}\}">m</figure-callout>}{V}_{}{}_1}{{\mathrm{PH}}_2-{\mathrm{<figure-callout\; id="1"\; label="PH"\; filenames="HDA00002162506500011.png,HDA00002162506500021.png"\; state="\{\{state\}\}">PH</figure-callout>}}_1}$

Require the SLOPE value in following scope:

0.8×(0.19841t ₁+54.195)<|SLOPE|<1.1×(0.19841t ₁+54.195)

Otherwise show and make mistakes.

Slope represents the slope of PH electrode measurement.

1.5, measure

Sampling mV _x

MV _X0The instantaneous millivolt of the measurement value that represents solution to be measured.

MV _xThe measurement millivolt value that represents solution to be measured.

Stable condition: begin timing 30s after pressing the measurement key, require:

1. mV in first 10s behind the 30s _X0Variation is write down last mV less than 0.5mV if set up _X0Be worth, and turn steady state (SS), at this moment mV _x=mV _X0

If 2. first 10s does not surely get off, time-delay is judged by top method again, writes down last mV _X0Value, at this moment mV _x=mV _X0

If 3. 30 " also stablely in do not get off, show error message

Calculate: if a) t ₂=t ₁(equivalent state is kept continuous 0.5s and is equated with worthwhile)

$\mathrm{Slope}=\frac{m{V}_2-\mathrm{<figure-callout\; id="1"\; label="m\; V"\; filenames="HDA00002162506500011.png,HDA00002162506500021.png"\; state="\{\{state\}\}">m</figure-callout>}{V}_{}{}_1}{{\mathrm{PH}}_2-{\mathrm{<figure-callout\; id="1"\; label="PH"\; filenames="HDA00002162506500011.png,HDA00002162506500021.png"\; state="\{\{state\}\}">PH</figure-callout>}}_1}$

${\mathrm{PH}}_x={\mathrm{<figure-callout\; id="1"\; label="PH"\; filenames="HDA00002162506500011.png,HDA00002162506500021.png"\; state="\{\{state\}\}">PH</figure-callout>}}_1+\frac{m{V}_x-\mathrm{<figure-callout\; id="1"\; label="m\; V"\; filenames="HDA00002162506500011.png,HDA00002162506500021.png"\; state="\{\{state\}\}">m</figure-callout>}{V}_{}{}_1}{\mathrm{Slope}}$

Show at last PH _xValue.

PH _xThe measurement pH value that represents solution to be measured

Annotate: such as PH _x＜0 or PH _x14 demonstration error messages

B) such as t ₂≠ t ₁

According to t ₁And t ₂Calculate PH from following formula _x

$\mathrm{<figure-callout\; id="1"\; label="m\; V"\; filenames="HDA00002162506500011.png,HDA00002162506500021.png"\; state="\{\{state\}\}">m</figure-callout>}{V}_{}^{}{}_1^{\&prime;}=\frac{(7.793-{\mathrm{<figure-callout\; id="1"\; label="PH"\; filenames="HDA00002162506500011.png,HDA00002162506500021.png"\; state="\{\{state\}\}">PH</figure-callout>}}_1^{\&prime;})(0.19841{\mathrm{<figure-callout\; id="2"\; label="t"\; filenames="HDA00002162506500021.png"\; state="\{\{state\}\}">t</figure-callout>}}_2+54.195)}{(7.793-{\mathrm{PH}}_1)(0.19841{\mathrm{<figure-callout\; id="1"\; label="t"\; filenames="HDA00002162506500011.png,HDA00002162506500021.png"\; state="\{\{state\}\}">t</figure-callout>}}_1+54.195)}\mathrm{<figure-callout\; id="1"\; label="m\; V"\; filenames="HDA00002162506500011.png,HDA00002162506500021.png"\; state="\{\{state\}\}">m</figure-callout>}{V}_{}{}_1$

$\mathrm{<figure-callout\; id="2"\; label="m\; V"\; filenames="HDA00002162506500021.png"\; state="\{\{state\}\}">m</figure-callout>}{V}_{}^{}{}_2^{\&prime;}=\frac{(7.793-{\mathrm{<figure-callout\; id="2"\; label="PH"\; filenames="HDA00002162506500021.png"\; state="\{\{state\}\}">PH</figure-callout>}}_2^{\&prime;})(0.19841{\mathrm{<figure-callout\; id="2"\; label="t"\; filenames="HDA00002162506500021.png"\; state="\{\{state\}\}">t</figure-callout>}}_2+54.195)}{(7.793-{\mathrm{PH}}_2)(0.19841{\mathrm{<figure-callout\; id="1"\; label="t"\; filenames="HDA00002162506500011.png,HDA00002162506500021.png"\; state="\{\{state\}\}">t</figure-callout>}}_1+54.195)}\mathrm{<figure-callout\; id="2"\; label="m\; V"\; filenames="HDA00002162506500021.png"\; state="\{\{state\}\}">m</figure-callout>}{V}_{}{}_2$

${\mathrm{Slope}}^{\&prime;}=\frac{\mathrm{<figure-callout\; id="2"\; label="m\; V"\; filenames="HDA00002162506500021.png"\; state="\{\{state\}\}">m</figure-callout>}{V}_{}^{}{}_2^{\&prime;}-\mathrm{<figure-callout\; id="1"\; label="m\; V"\; filenames="HDA00002162506500011.png,HDA00002162506500021.png"\; state="\{\{state\}\}">m</figure-callout>}{V}_{}^{}{}_1^{\&prime;}}{\mathrm{<figure-callout\; id="2"\; label="P\; H"\; filenames="HDA00002162506500021.png"\; state="\{\{state\}\}">P</figure-callout>}{H}_{}^{}{}_2^{\&prime;}\mathrm{<figure-callout\; id="1"\; label="P\; H"\; filenames="HDA00002162506500011.png,HDA00002162506500021.png"\; state="\{\{state\}\}">P</figure-callout>}{H}_{}^{}{}_1^{\&prime;}}$

${\mathrm{PH}}_x={\mathrm{<figure-callout\; id="1"\; label="PH"\; filenames="HDA00002162506500011.png,HDA00002162506500021.png"\; state="\{\{state\}\}">PH</figure-callout>}}_1^{\&prime;}+\frac{m{V}_x-\mathrm{<figure-callout\; id="1"\; label="m\; V"\; filenames="HDA00002162506500011.png,HDA00002162506500021.png"\; state="\{\{state\}\}">m</figure-callout>}{V}_{}^{}{}_1^{\&prime;}}{{\mathrm{Slope}}^{\&prime;}}$

The indication 1.6 make mistakes

1. Er ₁: the super scope of standard sepage

2. Er ₂: the sepage of 2 sepage same points

3. Er ₃: 60s does not surely get off when calibration and measurement

4. Er ₄: the PH measurement exceeds 0～14

The mV measurement exceeds ± 1999.9mV

5. Er ₅: temperature exceeds (0～60 ° of C) in calibration and measurement situation

6. Er ₆: Er ₆The super scope of electrode slope

7. Er ₇: Er ₇Illegal operation

2, the automatic identifying method of standard solution

Be illustrated in figure 3 as the scope schematic diagram of the standard solution pH value of patent PH electrode output of the present invention.Standard solution commonly used mainly contains three kinds: PH=10, and PH=6 and PH=4, according to the difference of variation of ambient temperature, the scope of the solution millivolt value that the PH electrode records is as follows:

The scope of the millivolt value of the titer of PH=10 is-156mV～-36mV;

The scope of the millivolt value of the titer of PH=6 is-20mV～100mV;

The scope of the millivolt value of the titer of PH=4 is 150mV～270mV;

Amplify 5 times with operational amplifier, single-chip microcomputer gathers, and comes discrimination standard liquid according to the millivolt value mVX of the titer that collects:

-780mV≤mVX≤-180mV, be the titer of PH=10;

-100mV≤mVX≤500mV is the titer of PH=6;

750mV≤mVX≤1375mV is the titer of PH=6;

All the other scopes are made error handling processing.

Claims (6)

1. high-precision intelligent acidometer, comprise single chip circuit, the A/D change-over circuit, man-machine interface circuit and power circuit, the A/D change-over circuit is connected with single chip circuit with the man-machine interface circuit and is connected, it is characterized in that, the A/D change-over circuit comprises temperature sensor, the PH sensor, the first operational amplifier, the second operational amplifier, multiway analog switch and A/D converter, temperature sensor, the output of PH sensor is respectively through first, the second operational amplifier is connected to a plurality of input ends of one of them passage of multiway analog switch, the output terminal of described one of them passage is connected with A/D converter, the output terminal of another passage of multiway analog switch is connected to the inverting input of the second operational amplifier, wherein two input ends of described another passage connect respectively the resistance of different resistances, switch for range, the address end of multiway analog switch is connected with single chip circuit.

2. high-precision intelligent acidometer as claimed in claim 1 is characterized in that the signal of PH sensor output after the second operational amplifier amplifies, X passage input end X0 and the X1 of access multiway analog switch.

3. high-precision intelligent acidometer as claimed in claim 1 is characterized in that the signal of temperature sensor output after the first operational amplifier amplifies, the X passage input end X3 of access multiway analog switch.

4. such as the arbitrary described high-precision intelligent acidometer of claim 1 ~ 3, it is characterized in that the output terminal of the Y passage of multiway analog switch is connected to the inverting input of the second operational amplifier, its input end Y0 and Y1 connect respectively the resistance of different resistances.

5. the measuring method of high-precision intelligent acidometer as claimed in claim 1, it is characterized in that temperature compensation, adopt the temperature sensor measurement environment temperature, standard solution to non-standard temperature is proofreaied and correct, single chip circuit adopts different formulas to calculate according to different temperature ranges, obtain the pH value of the standard solution under the environment temperature, concrete grammar is as follows:

Some timings:

0

～50

50

～60

Wherein, PH ₁The measurement pH value that represents some calibration standard solution, t ₁Represent the ambient temperature value that a point calibration is measured;

During two point calibrations:

0

～50

50

～60

Wherein, PH ₂The measurement pH value that represents two point calibration standard solution, t ₂Represent the ambient temperature value that two point calibrations are measured.

6. the measuring method of high-precision intelligent acidometer as claimed in claim 5, it is characterized in that when carrying out a point calibration and two point calibrations, millivolt value according to the accurate solution of PH sensor institute's mark, after operational amplifier amplifies, single chip circuit gathers the millivolt value after amplifying, and according to the automatic criterion of identification solution of millivolt value scope of various criterion solution.

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