CN218726863U - Low-cost two-wire system pH meter - Google Patents
Low-cost two-wire system pH meter Download PDFInfo
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- CN218726863U CN218726863U CN202123240497.9U CN202123240497U CN218726863U CN 218726863 U CN218726863 U CN 218726863U CN 202123240497 U CN202123240497 U CN 202123240497U CN 218726863 U CN218726863 U CN 218726863U
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Abstract
The utility model relates to a low-cost two-wire system pH meter, including the pH electrode, pH measuring module and pH calibration module, the signal output part of pH electrode is connected with pH measuring module's signal input part electricity, pH calibration module includes, resistance one, resistance two, resistance three and resistance four, the one end of resistance three is connected with pH measuring module's signal input part electricity, pH measuring module's signal output part is connected with resistance two's one end and resistance four's one end electricity, resistance three's the other end is connected with resistance two's the other end electricity, resistance one's one end is connected with pH measuring module's signal input part electricity, resistance one's the other end is connected with resistance four's the other end electricity; the utility model discloses a key control circuit, display screen drive circuit and display screen etc. that prepare traditional pH calibration module all remove, only realize the calibration through increasing three wires or wiring port and simple resistance-capacitance components and parts, have simplified the project organization of pH meter, have reduced production and installation cost.
Description
Technical Field
The utility model relates to a PH detecting instrument technical field, more specifically relate to a low-cost two-wire system pH meter.
Background
The pH meter is an instrument for measuring the pH value of a solution. The pH meter is a common analytical instrument and is widely applied to the fields of agriculture, environmental protection, industry and the like, the pH electrode is a consumable material, and in the using process, calibration and calibration are carried out according to the application condition so as to ensure the measuring precision.
The currently used online two-wire system pH meter generally has two calibration modes, one is an instrument with a key and a display, so that an operator can conveniently calibrate the instrument through the key and a display menu, the measurement precision is ensured, and the design cost of the instrument is increased; another scheme with low cost is that a key and a display part are eliminated, an instrument end directly outputs 4-20mA original signals, a collection end carries out secondary calibration after reading current, the operation is complex, the technical requirement on the collection end is high, calibration information is stored in the collection end and is separated from a field instrument, and when the instrument changes the installation position or the collection end, new calibration is needed.
SUMMERY OF THE UTILITY MODEL
In order to solve the traditional instrument that pH meter area button and demonstration, increased design cost's technical problem, the utility model provides a low-cost two-wire system pH meter.
The utility model discloses a realize above-mentioned purpose and specifically adopt following technical scheme:
the utility model provides a low-cost two-wire system pH meter, includes pH electrode, pH measuring module and pH calibration module, the signal output part of pH electrode with the signal input part electricity of pH measuring module is connected, pH calibration module includes resistance one, resistance two, resistance three and resistance four, the one end of resistance three with the signal input part electricity of pH measuring module is connected, the signal output part of pH measuring module with the one end of resistance two and the one end of resistance four is all connected electrically, the other end of resistance three with the other end electricity of resistance two is connected, the one end of resistance one with the signal input part electricity of pH measuring module is connected, the other end of resistance one with the other end electricity of resistance four is connected.
The utility model discloses a theory of operation: when the two-wire system circuit module is applied specifically, 5 external ports and/or 5 wires are set, wherein 2 external ports and/or 2 wires are respectively and electrically connected with a power input end and a signal output end of the two-wire system circuit module, and the other 3 external ports and/or wires are respectively a first wiring port and/or wire, a second wiring port and/or wire, a third wiring port and/or wire; the other end of the third resistor or the other end of the second resistor is electrically connected with one end of the first wiring port and/or one end of the first lead, the other end of the first resistor or the other end of the fourth resistor is electrically connected with one end of the second wiring port and/or one end of the second lead, and one end of the third wiring port and/or one end of the third lead is grounded; during calibration, an operator firstly puts the pH electrode 1 in standard liquid with the pH value of 6.86, when an output signal is stable, the first lead or the first port is in short circuit with a public lead, namely the third lead or the third port, and after the instrument calibration module detects the voltage change of the first port, the calibration of the standard liquid with the pH value of 6.86 is carried out; similarly, an operator firstly puts the pH electrode 1 in the standard solution with the pH value of 9.18, when the output signal is stable, the second lead or the second port is short-circuited with the common lead, namely the third lead or the third port, and the instrument calibration module calibrates the standard solution with the pH value of 9.18 after detecting the voltage change of the second port; when an operator puts the pH electrode 1 in the standard solution with the pH value of 4 and the signal output is stable, the first lead or the first port is in short circuit with the common lead, namely the third lead or the third port, and the second lead or the second port is in short circuit with the common lead, namely the third lead or the third port, and after the instrument calibration module detects the voltage change of the first port and the second port, the calibration of the standard solution with the pH value of 4 is carried out.
The utility model has the advantages that: the utility model discloses a key control circuit, display screen drive circuit and display screen etc. that prepare traditional pH calibration module all remove, only realize the calibration through increasing three wires or wiring port and simple resistance-capacitance components and parts, have simplified the project organization of pH meter, have reduced production and installation cost, calibrate easy operation moreover, do not have high expectations to personnel.
Furthermore, the system also comprises 5 external ports and/or 5 wires, wherein 2 external ports and/or 2 wires are respectively and electrically connected with the power input end and the signal output end of the two-wire system circuit module, and the other 3 external ports and/or wires are respectively a first wiring port and/or wire, a second wiring port and/or wire, a third wiring port and/or wire.
Further, the pH measuring module includes signal acquisition unit and MCU the control unit, the signal output part of signal acquisition unit with the signal input part electricity of MCU the control unit is connected, the one end of resistance three with the signal input part electricity of pH measuring module is connected, MCU the control unit's signal output part with the one end of resistance two and the equal electricity of one end of resistance four is connected, the other end of resistance three with the other end electricity of resistance two is connected, the one end of resistance one with the signal input part electricity of MCU the control unit is connected, the other end of resistance one with the other end electricity of resistance four is connected.
Furthermore, the other end of the third resistor or the other end of the second resistor is electrically connected with one end of the first wiring port and/or one end of the first wire, the other end of the first resistor or the other end of the fourth resistor is electrically connected with one end of the second wiring port and/or one end of the second wire, and one end of the third wiring port and/or one end of the third wire is grounded.
The pH measuring device further comprises a two-wire system circuit module, wherein the signal output end of the pH measuring module is electrically connected with the signal input end of the two-wire system circuit module, and the power supply input end of the pH measuring module is electrically connected with the signal output end of the two-wire system circuit module.
The two-wire circuit module is equivalent to a special load in the circuit, and is characterized in that the power consumption current of the two-wire circuit module is changed between 4 and 20mA according to the output of the pH measuring module. The ammeter only needs to be connected with the direct-current power supply in series in the positive and negative electrodes of the power supply access port of the two-wire system circuit module, so that the two-wire system circuit module only needs to be externally connected with 2 wires for data transmission.
Furthermore, the pH measuring module further comprises a conversion unit, the conversion unit comprises a D/a conversion chip and a voltage stabilizing chip, the signal output end of the MCU control unit is electrically connected to the signal input end of the D/a conversion chip, the signal output end of the D/a conversion chip is electrically connected to the signal input end of the two-wire circuit module, the signal output end of the two-wire circuit module is electrically connected to the signal input end of the voltage stabilizing chip, and the signal output end of the voltage stabilizing chip is electrically connected to the power input end of the MCU control unit.
Furthermore, the grounding end of the pH measurement module and the grounding end of the two-wire system circuit module are both grounded, and a resistor is connected in series between the grounding end of the two-wire system circuit module and the negative electrode of the power input end of the two-wire system circuit module.
Further, the pH measuring module further comprises a storage unit, and the storage unit is electrically connected with the MCU control unit.
Furthermore, the signal output end of the pH electrode is electrically connected with the signal input end of the signal acquisition unit, the MCU control unit is an embedded single chip microcomputer, and the I/O interface of the MCU control unit is electrically connected with the control port of the signal acquisition unit.
Further, the pH electrode is a composite electrode, and the composite electrode comprises a pH reference electrode, a pH glass electrode and a temperature sensor.
Drawings
Fig. 1 is a first schematic circuit diagram of the present invention;
fig. 2 is a schematic circuit diagram of the present invention;
FIG. 3 is an acquisition circuit diagram of a pH circuit module;
FIG. 4 is a circuit diagram of a mid-conversion circuit of the pH circuit block;
fig. 5 is a circuit diagram of a two-wire V/I converter circuit in a two-wire circuit module.
Reference numerals: 1. a pH electrode; 2. a pH measurement module; 3. a signal acquisition unit; 4. a conversion unit; 5. a two-wire circuit module; 6. a storage unit; 7. an MCU control unit; 8. and a pH calibration module.
Detailed Description
To make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the attached drawings in the embodiments of the present invention are combined to clearly and completely describe the technical solution in the embodiments of the present invention, and obviously, the described embodiments are part of the embodiments of the present invention, rather than all embodiments. The components of the embodiments of the present invention generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations.
Thus, the following detailed description of the embodiments of the invention, as presented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention.
It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, it need not be further defined and explained in subsequent figures.
Example one
As shown in fig. 1 to 2, the present embodiment provides a low-cost two-wire pH meter, which is characterized in that: including pH electrode 1, pH measuring module 2 and pH calibration module 8, the signal output part of pH electrode 1 with the signal input part electricity of pH measuring module 2 is connected, pH calibration module 8 includes, resistance R1, two R2 of resistance, three R3 of resistance and four R4 of resistance, the one end of resistance three R3 with the signal input part electricity of pH measuring module 2 is connected, the signal output part of pH measuring module 2 with the one end of resistance two R2 and the one end of resistance four R4 is all connected electrically, the other end of resistance three R3 with the other end electricity of resistance two R2 is connected, the one end of resistance R1 with the signal input part electricity of pH measuring module 2 is connected, the other end of resistance R1 with the other end electricity of resistance four R4 is connected.
Specifically, the two-wire system circuit module further comprises 5 external ports and/or 5 wires, wherein 2 external ports and/or 2 wires are respectively electrically connected with the power input end and the signal output end of the two-wire system circuit module 5, and the other 3 external ports and/or wires are respectively a first wiring port and/or wire, a second wiring port and/or wire, a third wiring port and/or wire.
Specifically, the other end of the resistor three R3 or the other end of the resistor two R2 is electrically connected to one end of the connection port one and/or the wire one, the other end of the resistor one R1 or the other end of the resistor four R4 is electrically connected to one end of the connection port two and/or the wire two, and one end of the connection port three and/or the wire three is grounded.
When the output signal is stable, the first lead or the first port and a common lead, namely the third lead or the third port are in short circuit, and the instrument calibration module calibrates the standard liquid with the pH value of 6.86 after detecting the voltage change of the first port; similarly, an operator firstly puts the pH electrode 1 in the standard solution with the pH value of 9.18, when the output signal is stable, the second lead or the second port is short-circuited with the common lead, namely the third lead or the third port, and the instrument calibration module calibrates the standard solution with the pH value of 9.18 after detecting the voltage change of the second port; when an operator puts the pH electrode 1 in the standard solution with the pH value of 4 and the signal output is stable, the first lead or the first port is in short circuit with the common lead, namely the third lead or the third port, and the second lead or the second port is in short circuit with the common lead, namely the third lead or the third port, and after the instrument calibration module detects the voltage change of the first port and the second port, the calibration of the standard solution with the pH value of 4 is carried out. When the meter performs real-time measurement, the third lead, the first lead and the second lead are all in a disconnected state, namely, are not mutually connected. The calibration of the pH meter is realized through the operation, the key operation and the calibration display operation in the traditional calibration mode are omitted, the product design cost is reduced, the calibration operation is simple, and the technical requirement on personnel is not high.
The signal output end of the pH electrode 1 is electrically connected with the signal acquisition unit input end of the pH measurement module 2, the signal output end of the conversion unit of the pH measurement module 2 is electrically connected with the signal input end of the two-wire system circuit module 5, and the power supply input end of the pH measurement module 2 is electrically connected with the signal output end of the two-wire system circuit module 5.
The pH measuring module 2 processes the value measured by the pH electrode 1 to obtain a voltage signal value of pH, sets a calibration parameter according to the pH stored in the pH measuring module 2, calculates an actual pH value, transmits the actual pH value to the two-wire circuit module 5, and reads a current parameter through an ammeter connected in series on the two-wire circuit module 5 to represent the pH value in a manner as follows: when the pH value of the solution to be detected is 4, the output of the ammeter is 8.57mA; when the pH value of the solution to be detected is 6.86, the output of the ammeter is 11.84mA; when the pH value of the tested solution is 9.18, the output of the ammeter is 14.49mA.
It should be noted that: the pH measuring module 2 processes the value measured by the pH electrode 1 into the prior art, such as: the patent with application number CN201510103088.4 describes in detail the method and device for measuring pH, and the principle related to the electric measurement of pH meter is also described in detail in "the principle of acidity pH meter" in Baidu library, therefore, the method for measuring pH value by using pH measuring module in this patent is prior art, and this patent does not relate to the computer program and the method for calculating pH.
As shown in fig. 2 to 4, the pH measurement module 2 includes a signal acquisition unit 3 and an MCU control unit 7, a signal output end of the signal acquisition unit 3 is electrically connected to a signal input end of the MCU control unit 7, a signal output end of the pH measurement module 2 is electrically connected to a signal input end of the two-wire circuit module 5, the pH calibration module is electrically connected to an I/O port of the MCU control unit 7, and a power input end of the pH measurement module 2 is electrically connected to a signal output end of the two-wire circuit module 5. The pH electrode 1 is a composite electrode, and the composite electrode comprises a pH reference electrode, a pH glass electrode and a temperature sensor.
The pH measuring module 2 further comprises a conversion unit 4 and a storage unit 6, the conversion unit 4 comprises a D/A conversion chip and a voltage stabilizing chip, the signal output end of the MCU control unit 7 is electrically connected with the signal input end of the D/A conversion chip, the signal output end of the D/A conversion chip is electrically connected with the signal input end of the two-wire circuit module 5, the signal output end of the two-wire circuit module 5 is electrically connected with the signal input end of the voltage stabilizing chip, and the signal output end of the voltage stabilizing chip is electrically connected with the power input end of the MCU control unit 7.
The storage unit 6 is a memory provided in the past when the amount of stored data is large; when the amount of stored data is small, the data can be directly stored on the internal FLASH in the MCU control unit 7, so as to reduce design cost and power consumption.
It should be noted that the present invention does not relate to a method for rewriting the program code in the MCU control unit 7, and at the same time, the present invention does not improve the method for changing the program code in the MCU control unit 7; the modification of the chip program of the MCU control unit 7 and the erase operation are common knowledge of those skilled in the art. Further, the erasing and recording operation of the chip program is also described in detail in "embedded system design" of a book published by 2-month mechanical industry press 2010.
The output port of the pH electrode 1 is electrically connected with the input port of the signal acquisition unit 3, and the MCU control unit 7 is an STM32L151CB embedded single chip microcomputer; the I/O interface of the MCU control unit 7 is electrically connected with the control port of the signal acquisition unit 3, the serial port of the MCU control unit 7 is electrically connected with the conversion unit 4, and the voltage output port of the conversion unit 4 is electrically connected with the voltage input unit of the two-wire system circuit module 5; the signal acquisition unit 3 is an LMP91200 integrated chip, the D/A conversion chip is DAC7512, and the voltage stabilization chip is NCP1422.
Specifically, the signal output end of the MCU control unit 7 is electrically connected to the signal input end of the D/a conversion chip, the signal output end of the D/a conversion chip is electrically connected to the signal input end of the two-wire circuit module 5, the signal output end of the two-wire circuit module 5 is electrically connected to the signal input end of the voltage stabilizing chip, and the signal output end of the voltage stabilizing chip is electrically connected to the power input end of the MCU control unit 7.
The two-wire system circuit module is a two-wire system V/I conversion circuit, the voltage output end of the pH measuring module is electrically connected with the voltage input end of the two-wire system V/I conversion circuit, the voltage input end of the pH measuring module is electrically connected with the voltage output end of the two-wire system V/I conversion circuit, and a resistor is connected in series between the grounding end of the pH measuring module and the negative electrode of the grounding end power supply input end of the two-wire system V/I conversion circuit.
The MCU control unit 7 selects a chip STM32L151CB embedded single chip microcomputer integrated chip with low power consumption. The instrument works by controlling the signal acquisition unit 3 mainly through an IO port of the MCU control unit 7, and the signal acquisition unit 3 acquires a measurement signal of the pH electrode 1 and sends the measurement signal to the MCU control unit 7 to calculate the pH value; finally, an IO port of the MCU control unit 7 controls the output conversion unit, the two-wire system circuit module 5 is further controlled, and the two-wire system circuit module 5 outputs current corresponding to 4-20mA according to the measured pH value to transmit the pH value; to reduce power consumption and save memory chip costs, calibration data may be saved directly on the internal FLASH in the MCU control unit 7.
Example two
As shown in fig. 1 to 2, the present embodiment provides a calibration method for a cost two-wire pH meter, which includes the following steps: as shown in fig. 1, a pH calibration module 8 is connected to the pH measurement module 2, and high and low voltages are collected through an I/O port of the MCU control unit 7 controlled by 3 lines to determine a pH calibration value, thereby calibrating the instrument. The calibration method comprises the following steps: the third conducting wire is a common wire, the first conducting wire is used for the standard solution with the calibrated pH value of 6.86, and the second conducting wire is used for the standard solution with the calibrated pH value of 9.18; the calibration of which pH standard liquid is to be calibrated is judged through an I/O port of an MCU control unit 7 in the pH measurement module 2, or whether an instrument is in a measurement state or a calibration state is judged, when a first lead and a common lead, namely a third lead, are connected together and conducted, a pH electrode 1 is placed in the standard liquid with the pH value of 6.86, and the calibration of the standard liquid with the pH value of 6.86 is automatically carried out through the MCU control unit 7; similarly, when the second lead wire and the common lead wire, namely the third lead wire, are connected together and conducted, the pH electrode 1 is placed in the standard solution with the pH value of 9.18, and the MCU control unit 7 automatically calibrates the 9.18 standard solution; when the first lead wire is connected with the common lead wire, namely the third lead wire, and the second lead wire is connected with the common lead wire, namely the third lead wire, the pH electrode 1 is placed in the standard solution with the pH value of 4, and the MCU control unit 7 automatically calibrates the standard solution with the pH value of 4. If the instrument is not calibrated and the instrument is measured in real time, the white line, the yellow line and the blue line are all in a disconnected state.
By the calibration method, the related circuit structures of the key control module and the display module can be omitted when the pH meter is designed, and the calibration function is realized by changing the interconnection mode of 3 output wires, so that the pH measurement data is accurate and reliable, the design cost is reduced, the technical requirement on operators is not high, and the personnel can conveniently maintain and calibrate.
EXAMPLE III
As shown in fig. 5, the present embodiment provides a conventional circuit structure of the two-wire circuit module 5, that is, the two-wire circuit module 5 described in this patent is a prior art, and its related applications are described as follows:
the two-wire V/I converter circuit 10 differs from a general V/I converter circuit in that: the voltage signal does not directly control the output current, but controls the self power consumption current of the whole circuit. Meanwhile, stable voltage is extracted from the current loop to supply power for the pH measuring circuit. In FIG. 5, OP1, Q1, R2, rs form a V/I converter. Analyzing the negative feedback process: if the point a is higher than 0V for some reason, the output of the operational amplifier OP1 rises, the voltage across Re rises, and the current through Re becomes large. The voltage at point B becomes low, corresponding to the increase in the entire power consumption, and the increase in the current passing through the sampling resistor Rs. The result is that the voltage at point a is pulled down by R2. Conversely, if the point a is somehow below 0V, it will also be raised by negative feedback and return to 0V. In summary, as a result of negative feedback, the OP1 is short and the voltage at point a is 0V. The control principle of Vo on the total power consumption is analyzed as follows: assuming that the output voltage of the pH measuring circuit is Vo, the current I1= Vo/R1 operational amplifier input end flowing through R1 cannot absorb current, I1 flows through R2 completely, and then the voltage VB = -I1 × R2= -Vo × R2/R1 at the point B takes R1= R2, there are only two resistors Rs and R2 between the VB = -Vo power supply negative and the whole transmitter circuit, so all the current flows through Rs and R2. The upper end of R2 is virtual earth 0V, and the upper end of Rs is GND. Therefore, the voltages at the two ends of R2 and Rs are identical and are equal to VB. Corresponding to Rs connected with R2 in parallel as a current sampling resistor. The total current of the circuit is therefore: if I s = Vo/(Rs// R2) and I s = Vo/Rs, then Rs =100 ohms in FIG. 5, and when the pH measurement circuit outputs 0.4-2V, the total current consumption is 4-20mA, and if R2> Rs cannot be met, rs is connected in parallel with R2, and (Rs// R2) is a fixed value, I s and Vo are still in a linear relation, and the error proportionality coefficient can be eliminated during calibration. R5 and U1 constitute a reference source, producing a stable reference voltage of 2.5V. The LM385 is a low-cost reference for micro power consumption, and can operate at 20uA or more, so the current is controlled to be about 100uA by R5. The OP2 forms a homodromous amplifier which amplifies the reference and supplies power to the pH measuring module 2. Because the voltage stabilizer with wide input voltage and low power consumption is rare, the cost is high; the use of reference amplification as a regulated power supply is an inexpensive solution. The partial circuit can also be an off-the-shelf integrated circuit. Such as XTR115/116/105, etc., the precision and stability are better than those of self-control, and the self-power consumption is lower.
Claims (10)
1. A low-cost two-wire system pH meter which characterized in that: including pH electrode (1), pH measuring module (2) and pH calibration module (8), the signal output part of pH electrode (1) with the signal input part electricity of pH measuring module (2) is connected, pH calibration module (8) is including resistance R1, two R2 of resistance, three R3 of resistance and resistance four R4, the one end of resistance three R3 with the signal input part electricity of pH measuring module (2) is connected, the signal output part of pH measuring module (2) with the one end of resistance two R2 and the one end of resistance four R4 is all connected electrically, the other end of resistance three R3 with the other end electricity of resistance two R2 is connected, the one end of resistance one R1 with the signal input part electricity of pH measuring module (2) is connected, the other end of resistance one R1 with the other end electricity of resistance four R4 is connected.
2. The low cost two-wire pH meter of claim 1, wherein: the three-wire-type power supply further comprises a two-wire-system circuit module (5), 5 external ports and/or 5 wires, wherein 2 external ports and/or 2 wires are electrically connected with a power supply input end and a signal output end of the two-wire-system circuit module (5) respectively, and the other 3 external ports and/or wires are respectively a wiring port I and/or a wire I, a wiring port II and/or a wire II and a wiring port III and/or a wire III.
3. The low cost two-wire pH meter of claim 2, wherein: the pH measuring module (2) comprises a signal acquisition unit (3) and an MCU control unit (7), the signal output end of the signal acquisition unit (3) is electrically connected with the signal input end of the MCU control unit (7), one end of a resistor three R3 is electrically connected with the signal input end of the pH measuring module (2), the signal output end of the MCU control unit (7) is electrically connected with one end of a resistor two R2 and one end of a resistor four R4, the other end of the resistor three R3 is electrically connected with the other end of the resistor two R2, one end of a resistor R1 is electrically connected with the signal input end of the MCU control unit (7), and the other end of the resistor R1 is electrically connected with the other end of the resistor four R4.
4. The low cost two-wire pH meter of claim 2, wherein: the other end of the resistor III R3 or the other end of the resistor II R2 is electrically connected with one end of the wiring port I and/or one end of the lead I, the other end of the resistor I R1 or the other end of the resistor IV R4 is electrically connected with one end of the wiring port II and/or one end of the lead II, and one end of the wiring port III and/or one end of the lead III are grounded.
5. The low cost two-wire pH meter of claim 3, wherein: the signal output end of the pH measuring module (2) is electrically connected with the signal input end of the two-wire system circuit module (5), and the power supply input end of the pH measuring module (2) is electrically connected with the signal output end of the two-wire system circuit module (5).
6. The low cost two-wire pH meter of claim 5, wherein: the pH measuring module (2) further comprises a conversion unit (4), the conversion unit (4) comprises a D/A conversion chip and a voltage stabilizing chip, the signal output end of the MCU control unit (7) is electrically connected with the signal input end of the D/A conversion chip, the signal output end of the D/A conversion chip is electrically connected with the signal input end of the two-wire system circuit module (5), the signal output end of the two-wire system circuit module (5) is electrically connected with the signal input end of the voltage stabilizing chip, and the signal output end of the voltage stabilizing chip is electrically connected with the power input end of the MCU control unit (7).
7. The low cost two-wire pH meter of claim 6, wherein: the grounding end of the pH measuring module (2) and the grounding end of the two-wire system circuit module (5) are grounded, and a resistor is connected in series between the grounding end of the two-wire system circuit module (5) and the negative electrode of the power supply input end of the two-wire system circuit module (5).
8. The low cost two-wire pH meter of claim 3, wherein: the pH measuring module (2) further comprises a storage unit (6), and the storage unit (6) is electrically connected with the MCU control unit (7).
9. The low cost two-wire pH meter of claim 3, wherein: the signal output end of the pH electrode (1) is electrically connected with the signal input end of the signal acquisition unit (3), the MCU control unit (7) is an embedded single chip microcomputer, and the I/O interface of the MCU control unit (7) is electrically connected with the control port of the signal acquisition unit (3).
10. The low cost two-wire pH meter of claim 1, wherein: the pH electrode (1) is a composite electrode, and the composite electrode comprises a pH reference electrode, a pH glass electrode and a temperature sensor.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202123240497.9U CN218726863U (en) | 2021-12-22 | 2021-12-22 | Low-cost two-wire system pH meter |
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| CN202123240497.9U CN218726863U (en) | 2021-12-22 | 2021-12-22 | Low-cost two-wire system pH meter |
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| CN218726863U true CN218726863U (en) | 2023-03-24 |
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