CN202748329U - TDS (total dissolved solids) detection circuit - Google Patents
TDS (total dissolved solids) detection circuit Download PDFInfo
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- CN202748329U CN202748329U CN201220465299.4U CN201220465299U CN202748329U CN 202748329 U CN202748329 U CN 202748329U CN 201220465299 U CN201220465299 U CN 201220465299U CN 202748329 U CN202748329 U CN 202748329U
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Abstract
The utility model discloses a TDS (total dissolved solids) detection circuit. The detection circuit comprises a water quality probe, a TDS detection unit with three branches, and a processing unit, wherein the first end of a first branch is connected with the first end of the water quality probe; the first end of a second branch is connected with the second end of the water quality probe; the first end of a third branch is connected with the first end and/or the second end of the water quality probe; the first output end of the processing unit is connected with the second end of the first branch; the second output end of the processing unit is connected with the second end of the second branch; the first input end of the processing unit is connected with the second end of the third branch; the two output ends of the processing unit are used for outputting pulse signals alternately; and the input end of the processing unit is used for acquiring TDS signals detected by the TDS detection unit. According to the utility model, the water quality probe can be driven to work by alternately loading voltage on the both ends of the water quality probe so as to avoid electrolytic reaction caused by persistently loading DC (direct current) voltage on the water quality probe, thereby improving TDS detection accuracy of water quality, avoiding influences on the water quality during detection and prolonging the service life of the water quality probe.
Description
Technical field
The utility model relates to water treatment field, in particular to the testing circuit of a kind of TDS.
Background technology
Total dissolved solid (TDS, Total Dissolved Solids) refers to the total amount of the solid that is dissolved in the water, measuring unit is parts per millions or mg/L, milligram/Liter, and physical significance is to be dissolved with what milligram total dissolved solids in 1 premium on currency.Popular says, the TDS value has represented dissolved matter impurity content in the water, and the TDS value is larger, illustrates that the impurity content in the water is large, water quality inferiority, on the contrary impurity content is little, and water quality is good.
At present, be the size of the TDS value of water for the most effective criterion of water quality, because the TDS value is larger, the electric conductivity of water is also better, its conductivity value is also larger; The TDS value is less, and electric conductivity is poorer, and conductivity is also less, thereby, can obtain by the conductivity degree that sample circuit obtains water the TDS value of water.
Present stage, the water quality detection of potable water needs national detection office or corresponding testing agency to come water quality is carried out determination and analysis with detecting instrument special-purpose, precision, but, because special-purpose, accurate detecting instrument cost is expensive, is difficult to be popularized at products such as comprising water purifier, water dispenser.And when adopting sample circuit of the prior art, because two syringe needle one ends of water quality probe can continue to be loaded a DC voltage, cause the water quality probe tip in water, electrolytic reaction can occur, in electrolytic reaction, the syringe needle of water quality shorting pin loaded voltage one end can continue loses electronics, impel syringe needle and then the loss of water quality shorting pin loaded voltage one end, thereby affect the serviceable life of water quality probe; Simultaneously, in the generating process of electrolytic reaction, the ion concentration in the water (near the ion concentration the water quality probe tip) can change along with continuing of electrolytic reaction, thereby affects accuracy of detection; The 3rd, the electrolytic reaction meeting of continuation impels increases a large amount of harmful ion and ionic compounds in the water, affect the degree of purity of water quality, and increased the pollution of water body.
There is electrolytic reaction when in the correlation technique TDS being detected and affects the serviceable life of water quality probe, the problem that affects accuracy of detection and affect the water quality degree of purity, not yet propose at present effective solution.
The utility model content
Fundamental purpose of the present utility model is to provide the testing circuit of a kind of TDS, has electrolytic reaction when to solve TDS being detected and affects the serviceable life of water quality probe, the problem that affects accuracy of detection and affect the water quality degree of purity.
To achieve these goals, comprise according to TDS testing circuit of the present utility model: the water quality probe is arranged in the aqueous solution; The TDS detecting unit, have the first branch road, the second branch road and the 3rd branch road, wherein, the first end of the first branch road is connected with the first end of water quality probe, the first end of the second branch road is connected with the second end of water quality probe, and the first end of the 3rd branch road is connected with first end and/or second end of water quality probe; And processing unit, the first output terminal of processing unit is connected with the second end of the first branch road, the second output terminal of processing unit is connected with the second end of the second branch road, the first input end of processing unit is connected with the second end of the 3rd branch road, the first output terminal and the second output terminal are used for alternately output pulse signal, and first input end is used for obtaining the TDS signal that the TDS detecting unit detects.
Further, this testing circuit also comprises: the temperature-sensitive bag; And temperature detecting unit, be connected respectively with processing unit with the temperature-sensitive bag, be used for gathering the temperature of aqueous solution, wherein, processing unit also comprises the second input end, the second input end is connected with temperature detecting unit, and processing unit also is used for determining according to the temperature of TDS signal and aqueous solution the TDS value of aqueous solution.
Further, the 3rd branch road comprises: rectification circuit is connected with the water quality probe; And filtering circuit, first end is connected with rectification circuit, and the second end is connected with the first input end of processing unit.
Further, filtering circuit comprises: the first electric capacity, and first end connects rectification circuit, the second end ground connection of the first electric capacity; The second electric capacity, first end connects rectification circuit, the second end ground connection of the second electric capacity; The first resistance, first end connects rectification circuit, the second end ground connection of the first resistance; The second resistance, first end connects rectification circuit, and the second end of the second resistance connects the first input end of processing unit; And the 3rd electric capacity, first end is connected in first node, the second end ground connection of the 3rd electric capacity, and wherein, first node is the second end of the second resistance and the node between the processing unit.
Further, rectification circuit comprises: the first diode, and the anodal first end that connects the water quality probe, the negative pole of the first diode connects the first end of the first electric capacity; And second diode, anodal the second end that connects the water quality probe, the negative pole of the second diode connects the first end of the first electric capacity.
Further, rectification circuit comprises: the 3rd diode, and anodal first end or the second end that connects the water quality probe, the negative pole of the 3rd diode connects the first end of the first electric capacity.
Further, rectification circuit comprises: the 4th diode, and the anodal first end that connects the water quality probe, the negative pole of the 4th diode connects the first end of the first electric capacity, the 5th diode, plus earth, the negative pole of the 5th diode connects the second end of water quality probe; The 6th diode, anodal the second end that connects the water quality probe, the negative pole of the 6th diode connects the first end of the first electric capacity; And the 7th diode, plus earth, the negative pole of the 7th diode connects the first end of water quality probe.
Further, the first branch road comprises the 3rd resistance, and the first end of the 3rd resistance is connected with the first end of water quality probe, and the 3rd resistance the second end is connected with the first output terminal of processing unit; And second branch road comprise the 4th resistance, the first end of the 4th resistance is connected with the second end of water quality probe, the 4th resistance the second end is connected with the second output terminal of processing unit.
Further, temperature detecting unit comprises: the 4th electric capacity, and first end connects temperature-sensitive bag, the second end ground connection of the 4th electric capacity; The 5th electric capacity, first end connects temperature-sensitive bag, the second end ground connection of the 5th electric capacity; The 5th resistance, first end connects temperature-sensitive bag, the second end ground connection of the 5th resistance; The 6th resistance, first end connects the temperature-sensitive bag, and the second end of the 6th resistance connects the second input end of processing unit; And the 6th electric capacity, first end is connected in Section Point, the second end ground connection of the 6th electric capacity, and wherein, Section Point is the second end of the 6th resistance and the node between the processing unit.
By the utility model, adopt the TDS testing circuit that comprises following part: be arranged at the water quality probe in the aqueous solution; TDS detecting unit with the first branch road, the second branch road and the 3rd branch road, wherein, the first end of the first branch road is connected with the first end of water quality probe, the first end of the second branch road is connected with the second end of water quality probe, and the first end of the 3rd branch road is connected with first end and/or second end of water quality probe; And processing unit, the first output terminal of processing unit is connected with the second end of the first branch road, the second output terminal of processing unit is connected with the second end of the second branch road, the first input end of processing unit is connected with the second end of the 3rd branch road, the first output terminal and the second output terminal are used for alternately output pulse signal, first input end is used for obtaining the TDS signal that the TDS detecting unit detects, replace output pulse signal by processing unit and replace on-load voltage to the two ends of water quality probe, avoid owing to the water quality probe being continued to load the electrolytic reaction that DC voltage causes, solved the serviceable life that has electrolytic reaction when TDS detected and affect the water quality probe, the problem that affects accuracy of detection and affect the water quality degree of purity, and then reached the TDS accuracy of detection of increasing water quality, when avoiding detecting on the impact of water quality and prolong the water quality probe effect in serviceable life.
Description of drawings
The accompanying drawing that consists of the application's a part is used to provide further understanding of the present utility model, and illustrative examples of the present utility model and explanation thereof are used for explaining the utility model, do not consist of improper restriction of the present utility model.In the accompanying drawings:
Fig. 1 is the theory diagram according to the TDS testing circuit of the utility model the first embodiment;
Fig. 2 is the theory diagram according to the TDS testing circuit of the utility model the second embodiment;
Fig. 3 is the water quality sampling value-TDS curve synoptic diagram under the different temperatures;
Fig. 4 is the connection diagram according to the TDS testing circuit of the utility model the first embodiment;
Fig. 5 is the connection diagram according to the TDS testing circuit of the utility model the second embodiment;
Fig. 6 is the connection diagram according to the TDS testing circuit of the utility model the 3rd embodiment;
Fig. 7 is the connection diagram according to the TDS testing circuit of the utility model the 4th embodiment; And
Fig. 8 is the process flow diagram according to the TDS detection method of the utility model embodiment.
Embodiment
Need to prove, in the situation that do not conflict, embodiment and the feature among the embodiment among the application can make up mutually.Describe below with reference to the accompanying drawings and in conjunction with the embodiments the utility model in detail.
Fig. 1 is the theory diagram according to the TDS testing circuit of the utility model the first embodiment, and as shown in Figure 1, this TDS testing circuit comprises water quality probe, TDS detecting unit and processing unit.
The water quality probe is arranged in the aqueous solution, drives by drive voltage signal, and for detection of the TDS of aqueous solution, wherein, this drive voltage signal can replace on-load voltage at the two ends of water quality probe.Particularly, drive voltage signal is produced by processing unit, this processing unit has the first output terminal and the second output terminal, two output terminals replace output pulse signal, and the first output terminal is connected with the first end of water quality probe via the first branch road of TDS detecting unit, and the second output terminal is connected with the second end of water quality probe via the second branch road of TDS detecting unit, wherein, when the first output terminal output high level, the first end of water quality probe is high level, and the second end is low level; When the second output terminal output high level, the second end of water quality probe is high level, and first end is low level, thereby realizes that alternately on-load voltage is to the two ends of water quality probe.
The water quality probe is under the driving of drive voltage signal, produce the detection voltage that characterizes aqueous solution TDS, the 3rd branch road one end of TDS detecting unit connects the water quality probe, the other end is connected to the first input end of processing unit, the 3rd branch road gathers the detection voltage of water quality probe generation to form the TDS signal, and this TDS signal inputed to processing unit, so that processing unit is determined the TDS value of aqueous solution according to this TDS signal.
Wherein, processing unit comprises that logically signal generation divides and signal processing, can be realized by different chips respectively, also can be realized by same chip.
In this embodiment, two delivery outlets by processing unit replace output pulse signal, replace on-load voltage to the two ends of water quality probe, thereby avoid the water quality probe continue is loaded DC voltage and causes the water quality probe that electrolytic reaction occurs in aqueous solution, so improved water quality TDS accuracy of detection, when avoiding detecting on the impact of water quality and can prolong serviceable life of water quality probe.
The TDS testing circuit that adopts this embodiment to provide, avoid to provide voltage drive signals for the water quality probe with DC voltage, thereby can prevent that the water quality probe from electrolytic reaction occuring when potable water is carried out water quality detection, ion and ionic compound that electrolysis is separated out produce secondary pollution to potable water, and the detection syringe needle of water quality probe can use food-grade safety detection material, further guarantees the precision of water quality detection and prevent that it from chemical reaction occuring in water.
Because the reacting phenomenon that this embodiment can avoid the water quality probe to produce electrolysis in water is so can prolong the serviceable life of water quality probe; Simultaneously, the voltage of alternative expression drive can be stable the water quality probe that impels carry out the sampling of TDS value, can not change owing to electrolytic reaction causes the water quality ion concentration, and the sampling precision during interference water quality probe in detecting.The voltage driving mode of this alternative expression is similar to exchange and drives, what detect all is 1/f (f is the frequency of pulse signal) sampled value constantly, quick sampling can avoid because the flowability of the ion that generates in the water body or liquid on the impact of the stability of sampling.
Fig. 2 is the theory diagram according to the TDS testing circuit of the utility model the second embodiment, and as shown in Figure 2, this TDS testing circuit comprises water quality probe, TDS detecting unit, temperature-sensitive bag, temperature detecting unit and processing unit.
Wherein, the water quality probe is arranged in the aqueous solution, drives by drive voltage signal, TDS for detection of aqueous solution, this drive voltage signal is produced by processing unit, and is loaded on the water quality probe via the TDS detecting unit, to replace on-load voltage to the two ends of water quality probe.The water quality probe produces the detection voltage that characterizes aqueous solution TDS under the driving of drive voltage signal, the TDS detecting unit gathers the detection voltage of water quality probe generation with formation TDS signal, and this TDS signal is inputed to processing unit.
In water quality probe in detecting aqueous solution TDS,, the temperature-sensitive bag detects in real time the temperature of aqueous solution by being set.Temperature detecting unit is connected respectively with processing unit with the temperature-sensitive bag, gathers the temperature of the aqueous solution that the temperature-sensitive bag detects, and the temperature that detects is inputed to processing unit, the TDS value that processing unit is determined aqueous solution according to temperature and the TDS signal of aqueous solution.
The people studies discovery through utility model, as shown in Figure 3, and for identical water quality TDS, when water temperature not simultaneously, the TDS sampled value that the TDS signal is corresponding is different, for example, and when TDS is 25mg/L, the sampled value that obtains when water temperature is 1 ℃ is 185, and the sampled value that water temperature obtains when being 25 ℃ is less than 175, thereby, when water quality TDS detects, if do not consider the impact of water temperature, the TDS that determines of processing unit is inaccurate so.
In this embodiment, the temperature of aqueous solution solution as the condition of determining TDS, overcoming water temperature to the impact of TDS accuracy, thereby has been improved the accuracy that water quality TDS detects.
Preferably, when processing unit is determined the TDS value of aqueous solution according to the temperature of aqueous solution and TDS sampled value (sampled value that the TDS signal is corresponding), at first according to the temperature correction water quality sampling value of aqueous solution, then according to revised sampled value and default sampled value-TDS curve, determine the TDS of aqueous solution, wherein, when default sampled value-TDS curve is the sampled value of water temperature when being the first temperature-TDS curve, comprises according to the temperature correction water quality sampling value of aqueous solution and to adopt following formula correction:
TDS_AD
After the correction=TDS_AD
Before the correction+ (T
Water-T
1) % Δ T
Wherein, TDS_AD
After the correctionBe revised water quality sampling value, TDS_AD
Before the correctionBe the water quality sampling value that gets access to, T
WaterBe the temperature of aqueous solution, T
1Be the first temperature, Δ T is default compensation temperature.
As shown in Figure 3, because the temperature of aqueous solution is during less than 20 ℃, under the identical TDS, the water quality sampling value that records during different temperatures differs greatly, further preferably, when the temperature of aqueous solution during less than 20 ℃, the sample method of above-mentioned correction sampled value of processing unit is determined the TDS value of aqueous solution.
For example, water quality sampling value when detecting 1 ℃ and 10 ℃ times different TDS values by the special-purpose conductivity meter (precision is high, expensive) that detects water quality TDS, the sampled value that obtains presetting-TDS curve, when the temperature of aqueous solution is 4 ℃, after processing unit receives the TDS signal, the sampled value that the TDS signal is corresponding is revised: TDS_AD
After the correction=TDS_AD
Before the correctionThen+(4-1) %2 determines the TDS of aqueous solution by the sampled value under 1 ℃-TDS curve; When the temperature of aqueous solution is 15 ℃, after processing unit receives the TDS signal, the sampled value that the TDS signal is corresponding is revised: TDS_AD
After the correction=TDS_AD
Before the correctionThen+(15-10) %2 determines the TDS of aqueous solution by the sampled value under 10 ℃-TDS curve.
Preferably, processing unit is preset a plurality of temperature ranges, the reference temperature that the different temperatures scope is corresponding different, sampled value when prestoring each reference temperature-TDS curve, when processing unit is determined the TDS value of aqueous solution according to the temperature of aqueous solution and TDS sampled value (sampled value that the TDS signal is corresponding), which temperature range is the temperature of determining first aqueous solution be in, then determine the reference temperature corresponding to temperature of aqueous solution according to the temperature range of determining, at last according to the sampled value of water quality sampling value and the reference temperature determined-TDS curve, determine the TDS of aqueous solution.
As shown in Figure 3, because the temperature of aqueous solution is during more than or equal to 20 ℃, under the identical TDS, the water quality sampling value difference that records during different temperatures is different less, and the water quality sampling value when then adopting close temperature replaces the actual water quality sampling value of obtaining to determine the TDS of aqueous solution, and method is simple and little on the accuracy impact of TDS, therefore, further preferably, when the temperature of aqueous solution during more than or equal to 20 ℃, the method for the above-mentioned default a plurality of reference temperatures of processing unit sampling is determined the TDS value of aqueous solution.
For example, certain default temperature range is 27 ℃～31 ℃, reference temperature corresponding to this temperature range is 29 ℃, water quality sampling value when detecting 29 ℃ of lower different TDS by the special-purpose conductivity meter (precision is high, expensive) that detects water quality TDS, the sampled value that obtains presetting-TDS curve, when the temperature of aqueous solution is 28 ℃, processing unit determines that water temperature is in 27 ℃～31 ℃, and then definite reference temperature is 29 ℃, at last according to the sampled value of water quality sampling value and 29 ℃-TDS curve, determine the TDS of aqueous solution.
Adopt above-mentioned preferred embodiment, sampled value under the reference temperature that only need prestore-TDS curve, and adopt diverse ways to determine the TDS value of aqueous solution at different aqueous temperatures, just can obtain accurately the TDS value of aqueous solution, can realize that by the simple detection circuit somewhat complex design instrument detects effect, simple and convenient, as to save TDS testing cost.
Fig. 4 is the connection diagram according to the TDS testing circuit of the utility model the first embodiment, and as shown in Figure 4, the water quality probe CN1 of TDS testing circuit is for detection of the TDS of aqueous solution, and its drive voltage signal is provided via the TDS detecting unit by processing unit.
Processing unit realizes having the first delivery outlet Q-A, the second delivery outlet Q-B and the first input port Q-TDS by the single-chip microcomputer (not shown).
The first branch road of TDS detecting unit comprises that the first end of the 3rd resistance R 3, the three resistance R 3 is connected with the first end of water quality probe CN1, and the second end of the 3rd resistance R 3 is connected to the first delivery outlet Q-A of single-chip microcomputer.
The second branch road of TDS detecting unit comprises that the first end of the 4th resistance R 4, the four resistance R 4 is connected with the second end of water quality probe CN1, and the 4th resistance R 4 second ends are connected to the second delivery outlet Q-B of single-chip microcomputer.
The 3rd branch road of TDS detecting unit comprises the first diode D1, the second diode D2, the first capacitor C 1, the second capacitor C 2, the 3rd capacitor C 3, the first resistance R 1 and the second resistance R 2, wherein, the positive pole of the first diode D1 connects the first end of water quality probe CN1, and the negative pole of the first diode D1 connects the first end of the first capacitor C 1; The positive pole of the second diode D2 connects the second end of water quality probe CN1, and the negative pole of the second diode D2 connects the first end of the first capacitor C 1; The first end of the first capacitor C 1 and the first diode D1 be connected the negative pole of diode D2 and all be connected the second end ground connection of the first capacitor C 1; The second capacitor C 2 and the first resistance R 1 are in parallel with the first capacitor C 1 respectively; The first end of the second resistance R 2 and the first diode D1 be connected the negative pole of diode D2 and all be connected, the second end of the second resistance R 2 connects the first input port Q-TDS of single-chip microcomputer; Between the second end of the second resistance R 2 and single-chip microcomputer a node is set, the first end of the 3rd capacitor C 3 is connected to this node, the second end ground connection of the 3rd capacitor C 3.
The principle of work of this circuit is as follows: when the first input port Q-A input high level in the testing circuit, the second corresponding input port Q-B is input as low level, then add the 4th resistance R 4 total resistances by the 3rd resistance R 3 with the conductivity of measuring solution and carry out dividing potential drop, voltage is through the first diode D1, and carry out filtering through filtering the first capacitor C 1 and the second capacitor C 2, then carry out voltage detecting through the second resistance R 2 (being current-limiting resistance) and the 3rd capacitor C 3 (being filter capacitor) and by the chip detection mouth; Otherwise, when the second input port Q-B input high level in the testing circuit, the first corresponding input port Q-A is input as low level, then add the 3rd resistance R 3 total resistances by the 4th resistance R 4 with the conductivity of measuring solution and carry out dividing potential drop, voltage is through the second diode D2, and carry out filtering through filtering the first capacitor C 1 and the second capacitor C 2, then carry out voltage detecting through the second resistance R 2 and the 3rd capacitor C 3 and by the chip detection mouth, the first resistance R 1 is the discharge resistance of the first electric capacity and the second electric capacity, and the frequency of circuit input high-low level is 50KHz.
Single-chip microcomputer is alternately exported the pulse signal of certain frequency by two delivery outlets, for example sinusoidal wave pulse signal or rectangular wave pulse signal, replace on-load voltage to the two ends of water quality probe, thereby the direct current effect of avoiding continuing causes the water quality probe that electrolytic reaction occurs in aqueous solution.
Fig. 5 is the connection diagram according to the TDS testing circuit of the utility model the second embodiment, and as shown in Figure 5, the water quality probe CN1 of TDS testing circuit is for detection of the TDS of aqueous solution, and its drive voltage signal is provided via the TDS detecting unit by processing unit.
Processing unit realizes having the first delivery outlet Q-A, the second delivery outlet Q-B and the first input port Q-TDS by the single-chip microcomputer (not shown).
The first branch road of TDS detecting unit comprises that the first end of the 3rd resistance R 3, the three resistance R 3 is connected with the first end of water quality probe CN1, and the second end of the 3rd resistance R 3 is connected to the first delivery outlet Q-A of single-chip microcomputer.
The second branch road of TDS detecting unit comprises that the first end of the 4th resistance R 4, the four resistance R 4 is connected with the second end of water quality probe CN1, and the 4th resistance R 4 second ends are connected to the second delivery outlet Q-B of single-chip microcomputer.
The 3rd branch road of TDS detecting unit comprises the 3rd diode D3, the first capacitor C 1, the second capacitor C 2, the 3rd capacitor C 3, the first resistance R 1 and the second resistance R 2, wherein, the positive pole of the 3rd diode D3 connects the first end of water quality probe CN1, and the negative pole of the 3rd diode D3 connects the first end of the first capacitor C 1; The first end of the first capacitor C 1 is connected with the negative pole of the 3rd diode D3, the second end ground connection of the first capacitor C 1; The second capacitor C 2 and the first resistance R 1 are in parallel with the first capacitor C 1 respectively; The first end of the second resistance R 2 is connected with the negative pole of the 3rd diode D3, and the second end of the second resistance R 2 connects the first input port Q-TDS of single-chip microcomputer; Between the second end of the second resistance R 2 and single-chip microcomputer a node is set, the first end of the 3rd capacitor C 3 is connected to this node, the second end ground connection of the 3rd capacitor C 3.
The principle of work of this circuit is as follows: when the first input port Q-A input high level in the testing circuit, the second corresponding input port Q-B is input as low level, then add the 4th resistance R 4 total resistances by the 3rd resistance R 3 with the conductivity of measuring solution and carry out dividing potential drop, voltage is through the 3rd diode D3, and carry out filtering through filtering the first capacitor C 1 and the second capacitor C 2, then carry out voltage detecting through current-limiting resistance R2 and filter capacitor C3 and by the chip detection mouth; Otherwise, when the second input port Q-B input high level in the testing circuit, the first corresponding input port Q-A is input as low level, then add the 3rd resistance R 3 total resistances by the 4th resistance R 4 with the conductivity of measuring solution and carry out dividing potential drop, voltage is through the 3rd diode D3, and carry out filtering through filtering the first capacitor C 1 and the second capacitor C 2, then carry out voltage detecting through current-limiting resistance R2 and filter capacitor C3 and by the chip detection mouth; The first resistance R 1 is the discharge resistance of the first electric capacity and the second electric capacity, and the frequency of circuit input high-low level is 50KHz.
Fig. 6 is the connection diagram according to the TDS testing circuit of the utility model the 3rd embodiment, and as shown in Figure 6, the water quality probe CN1 of TDS testing circuit is for detection of the TDS of aqueous solution, and its drive voltage signal is provided via the TDS detecting unit by processing unit.
Processing unit realizes having the first delivery outlet Q-A, the second delivery outlet Q-B and the first input port Q-TDS by the single-chip microcomputer (not shown).
The first branch road of TDS detecting unit comprises that the first end of the 3rd resistance R 3, the three resistance R 3 is connected with the first end of water quality probe CN1, and the second end of the 3rd resistance R 3 is connected to the first delivery outlet Q-A of single-chip microcomputer.
The second branch road of TDS detecting unit comprises that the first end of the 4th resistance R 4, the four resistance R 4 is connected with the second end of water quality probe CN1, and the 4th resistance R 4 second ends are connected to the second delivery outlet Q-B of single-chip microcomputer.
The 3rd branch road of TDS detecting unit comprises the 4th diode D4, the 5th diode D5, the 6th diode D6, the 7th diode D7, the first capacitor C 1, the second capacitor C 2, the 3rd capacitor C 3, the first resistance R 1 and the second resistance R 2, wherein, the positive pole of the 4th diode D4 connects the first end of water quality probe CN1, and the negative pole of the 4th diode D4 connects the first end of the first capacitor C 1; The plus earth of the 5th diode D5, the negative pole of the 5th diode D5 connects the second end of water quality probe CN1; The positive pole of the 6th diode D6 connects the second end of water quality probe CN1, and the negative pole of the 6th diode D6 connects the first end of the first capacitor C 1; The plus earth of the 7th diode D7, the negative pole of the 7th diode D7 connects the first end of water quality probe CN1; The first end of the first capacitor C 1 is connected respectively with the negative pole of the 4th diode D4 and the 6th diode D6, the second end ground connection of the first capacitor C 1; The second capacitor C 2 and the first resistance R 1 are in parallel with the first capacitor C 1 respectively; The first end of the second resistance R 2 all is connected with the negative pole of the 4th diode D4 and the 6th diode D6, and the second end of the second resistance R 2 connects the first input port Q-TDS of single-chip microcomputer; Between the second end of the second resistance R 2 and single-chip microcomputer a node is set, the first end of the 3rd capacitor C 3 is connected to this node, the second end ground connection of the 3rd capacitor C 3.
The principle of work of this circuit is as follows: when the first input port Q-A input high level in the testing circuit, the second corresponding input port Q-B is input as low level, then add the 4th resistance R 4 total resistances by the 3rd resistance R 3 with the conductivity of measuring solution and carry out dividing potential drop, voltage is through the 4th diode D4, and carry out filtering through filtering the first capacitor C 1 and the second capacitor C 2, then carry out voltage detecting through current-limiting resistance R2 and filter capacitor C3 and by the chip detection mouth; Otherwise, when the second input port Q-B input high level in the testing circuit, the first corresponding input port Q-A is input as low level, then add the 3rd resistance R 3 total resistances by the 4th resistance R 4 with the conductivity of measuring solution and carry out dividing potential drop, voltage is through the 6th diode D6, and carry out filtering through filtering the first capacitor C 1 and the second capacitor C 2, then carry out voltage detecting through current-limiting resistance R2 and filter capacitor C3 and by the chip detection mouth; The first resistance R 1 is the discharge resistance of the first electric capacity and the second electric capacity, and the frequency of circuit input high-low level is 50KHz.
Fig. 7 is the connection diagram according to the TDS testing circuit of the utility model the 4th embodiment, and this embodiment comprises water quality probe and the TDS detecting unit that any embodiment provides among Fig. 4 to Fig. 6, also comprises temperature-sensitive bag CN2 and temperature sensing circuit.
Processing unit realizes having the first delivery outlet Q-A, the second delivery outlet Q-B, the first input port Q-TDS and the second input port Q-T by the single-chip microcomputer (not shown).
Wherein, the TDS detecting unit among this embodiment is described in detail hereinbefore, no longer repeats herein.As shown in Figure 7, temperature detecting unit comprises the 4th capacitor C 4, the 4th capacitor C 5, the 6th capacitor C 6, the 5th resistance R 5 and the 6th resistance R 6, and wherein, an end of the 4th capacitor C 4 connects temperature-sensitive bag, other end ground connection; The 5th capacitor C 5 and the 5th resistance R 5 are respectively at 4 parallel connections of the 4th capacitor C; The first end of the 6th resistance R 6 is connected with CN2, and the second end of the 6th resistance R 6 connects the second input port Q-T of single-chip microcomputer; Between the second end of the 6th resistance R 6 and single-chip microcomputer a node is set, the first end of the 6th capacitor C 6 is connected to this node, the second end ground connection of the 6th capacitor C 6.
The principle of work of this circuit is as follows: one termination of temperature-sensitive bag+5V power supply, another termination filter capacitor, discharge resistance and current-limiting resistance.When the temperature difference, be that the resistance that presents of the thermistor in the temperature-sensitive bag is also different, namely+5V carries out filtering through the voltage after the thermistor dividing potential drop through the 4th capacitor C 4 and the 5th capacitor C 5, passes through current-limiting resistance R6 and filter capacitor C6 again, then carries out voltage detecting by the chip detection port.The 5th resistance R 5 is the discharge resistance of the 4th electric capacity and the 5th electric capacity, and the frequency of circuit input high-low level is 50KHz,
In water quality probe in detecting aqueous solution TDS,, temperature-sensitive CN2 bag detects in real time the temperature of aqueous solution by being set, the TDS value that single-chip microcomputer is determined aqueous solution according to temperature and the TDS signal of aqueous solution.
Fig. 8 is the process flow diagram according to the TDS detection method of the utility model embodiment, and as shown in Figure 8, the method comprises that following step S102 is to step S106:
Step S102: alternately on-load voltage is to the two ends of water quality probe, to drive the TDS of water quality probe in detecting aqueous solution, wherein, the water quality probe is arranged in the aqueous solution, drive by drive voltage signal, this drive voltage signal can replace on-load voltage at the two ends of water quality probe.
Step S104: obtain the voltage signal that the water quality probe in detecting arrives, to obtain the TDS signal.
The water quality probe produces the detection voltage that characterizes aqueous solution TDS under the driving of drive voltage signal, obtain this voltage signal and obtain the TDS signal.
Step S106: the TDS value of determining aqueous solution according to the TDS signal.
In this embodiment, bring in the TDS that drives water quality probe in detecting aqueous solution by replacing on-load voltage to two of water quality probe, thereby avoid the water quality probe continue is loaded DC voltage and causes the water quality probe that electrolytic reaction occurs in aqueous solution, so improved water quality TDS accuracy of detection, when avoiding detecting on the impact of water quality and can prolong serviceable life of water quality probe.
Preferably, this TDS detection method also comprises the step of the temperature that gathers aqueous solution, and wherein, step S106 is for determining the TDS value of aqueous solution according to the temperature of TDS signal and aqueous solution.
Adopt the preferred embodiment, the temperature of aqueous solution solution as the condition of determining TDS, overcoming water temperature to the impact of TDS accuracy, thereby has been improved the accuracy of water quality TDS detection.
Further preferably, when determining the TDS value of aqueous solution according to the temperature of TDS signal and aqueous solution, can adopt above the method for the correction sampled value of describing to determine the TDS value of aqueous solution, the method of the default a plurality of reference temperatures described of also can sampling is above determined the TDS value of aqueous solution, and detailed process repeats no more herein.
From above description, can find out, the utility model has been realized following technique effect: two delivery outlets by processing unit replace output pulse signal, replace on-load voltage to the two ends of water quality probe, thereby avoid the water quality probe continue is loaded DC voltage and causes the water quality probe that electrolytic reaction occurs in aqueous solution, so improved water quality TDS accuracy of detection, when avoiding detecting on the impact of water quality and can prolong serviceable life of water quality probe.
The above is preferred embodiment of the present utility model only, is not limited to the utility model, and for a person skilled in the art, the utility model can have various modifications and variations.All within spirit of the present utility model and principle, any modification of doing, be equal to replacement, improvement etc., all should be included within the protection domain of the present utility model.
Claims (9)
1. a TDS testing circuit is characterized in that, comprising:
The water quality probe is arranged in the aqueous solution;
The TDS detecting unit, have the first branch road, the second branch road and the 3rd branch road, wherein, the first end of described the first branch road is connected with the first end of described water quality probe, the first end of described the second branch road is connected with the second end of described water quality probe, and the first end of described the 3rd branch road is connected with first end and/or second end of described water quality probe; And
Processing unit, the first output terminal of described processing unit is connected with the second end of described the first branch road, the second output terminal of described processing unit is connected with the second end of described the second branch road, the first input end of described processing unit is connected with the second end of described the 3rd branch road, described the first output terminal and described the second output terminal are used for alternately output pulse signal, and described first input end is used for obtaining the TDS signal that described TDS detecting unit detects.
2. TDS testing circuit according to claim 1 is characterized in that, also comprises:
The temperature-sensitive bag; And
Temperature detecting unit is connected respectively with described processing unit with described temperature-sensitive bag, is used for gathering the temperature of described aqueous solution,
Wherein, described processing unit also comprises the second input end, and described the second input end is connected with described temperature detecting unit, and described processing unit also is used for determining according to the temperature of described TDS signal and described aqueous solution the TDS value of described aqueous solution.
3. TDS testing circuit according to claim 1 and 2 is characterized in that, described the 3rd branch road comprises:
Rectification circuit is connected with described water quality probe; And
Filtering circuit, first end is connected with described rectification circuit, and the second end is connected with the first input end of described processing unit.
4. TDS testing circuit according to claim 3 is characterized in that, described filtering circuit comprises:
The first electric capacity (C1), first end connects described rectification circuit, the second end ground connection of described the first electric capacity (C1);
The second electric capacity (C2), first end connects described rectification circuit, the second end ground connection of described the second electric capacity (C2);
The first resistance (R1), first end connects described rectification circuit, the second end ground connection of described the first resistance (R1);
The second resistance (R2), first end connects described rectification circuit, and the second end of described the second resistance (R2) connects the first input end (Q-TDS) of described processing unit; And
The 3rd electric capacity (C3), first end is connected in first node, the second end ground connection of described the 3rd electric capacity (C3), wherein, described first node is the second end of described the second resistance (R2) and the node between the described processing unit.
5. TDS testing circuit according to claim 4 is characterized in that, described rectification circuit comprises:
The first diode (D1), the anodal first end that connects described water quality probe, the negative pole of described the first diode (D1) connects the first end of described the first electric capacity (C1); And
The second diode (D2), anodal the second end that connects described water quality probe, the negative pole of described the second diode (D2) connects the first end of described the first electric capacity (C1).
6. TDS testing circuit according to claim 4 is characterized in that, described rectification circuit comprises:
The 3rd diode (D3), anodal first end or the second end that connects described water quality probe, the negative pole of described the 3rd diode (D3) connects the first end of described the first electric capacity (C1).
7. TDS testing circuit according to claim 4 is characterized in that, described rectification circuit comprises:
The 4th diode (D4), the anodal first end that connects described water quality probe, the negative pole of described the 4th diode (D4) connects the first end of described the first electric capacity (C1),
The 5th diode (D5), plus earth, the negative pole of described the 5th diode (D5) connects the second end of described water quality probe;
The 6th diode (D6), anodal the second end that connects described water quality probe, the negative pole of described the 6th diode (D6) connects the first end of described the first electric capacity (C1); And
The 7th diode (D7), plus earth, the negative pole of described the 7th diode (D7) connects the first end of described water quality probe.
8. TDS testing circuit according to claim 1 and 2 is characterized in that,
Described the first branch road comprises the 3rd resistance (R3), the first end of described the 3rd resistance (R3) is connected with the first end of described water quality probe, and described the 3rd resistance (R3) the second end is connected with first output terminal (Q-A) of described processing unit; And
Described the second branch road comprises the 4th resistance (R4), the first end of described the 4th resistance (R4) is connected with the second end of described water quality probe, and described the 4th resistance (R4) the second end is connected with second output terminal (Q-B) of described processing unit.
9. TDS testing circuit according to claim 2 is characterized in that, described temperature detecting unit comprises:
The 4th electric capacity (C4), first end connect described temperature-sensitive bag, the second end ground connection of described the 4th electric capacity (C4);
The 5th electric capacity (C5), first end connect described temperature-sensitive bag, the second end ground connection of described the 5th electric capacity (C5);
The 5th resistance (R5), first end connect described temperature-sensitive bag, the second end ground connection of described the 5th resistance (R5);
The 6th resistance (R6), first end connect described temperature-sensitive bag, and the second end of described the 6th resistance (R6) connects second input end (Q-T) of described processing unit; And
The 6th electric capacity (C6), first end is connected in Section Point, the second end ground connection of described the 6th electric capacity (C6), wherein, described Section Point is the second end of described the 6th resistance (R6) and the node between the described processing unit.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201220465299.4U CN202748329U (en) | 2012-09-12 | 2012-09-12 | TDS (total dissolved solids) detection circuit |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201220465299.4U CN202748329U (en) | 2012-09-12 | 2012-09-12 | TDS (total dissolved solids) detection circuit |
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| CN202748329U true CN202748329U (en) | 2013-02-20 |
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| CN201220465299.4U Expired - Lifetime CN202748329U (en) | 2012-09-12 | 2012-09-12 | TDS (total dissolved solids) detection circuit |
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Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103675023A (en) * | 2012-09-12 | 2014-03-26 | 珠海格力电器股份有限公司 | Detection circuit and detection method of total dissolved solids (TDS) |
| CN104577976A (en) * | 2013-10-24 | 2015-04-29 | 珠海格力电器股份有限公司 | Arc fault protection device and control method thereof |
| CN104698040A (en) * | 2015-03-23 | 2015-06-10 | 滁州东润电子科技有限公司 | Water quality testing probe with TDS and temperature sensing functions |
| CN105067669A (en) * | 2015-06-30 | 2015-11-18 | 佛山市云米电器科技有限公司 | Detection circuit, detection apparatus and detection method |
| CN106053553A (en) * | 2016-07-26 | 2016-10-26 | 佛山科学技术学院 | Water quality monitor |
| CN109254326A (en) * | 2017-07-12 | 2019-01-22 | 美的智慧家居科技有限公司 | Water sensor and water sensor probe rust-proofing method |
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2012
- 2012-09-12 CN CN201220465299.4U patent/CN202748329U/en not_active Expired - Lifetime
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103675023A (en) * | 2012-09-12 | 2014-03-26 | 珠海格力电器股份有限公司 | Detection circuit and detection method of total dissolved solids (TDS) |
| CN103675023B (en) * | 2012-09-12 | 2017-03-22 | 珠海格力电器股份有限公司 | Detection circuit and detection method of total dissolved solids (TDS) |
| CN104577976A (en) * | 2013-10-24 | 2015-04-29 | 珠海格力电器股份有限公司 | Arc fault protection device and control method thereof |
| CN104577976B (en) * | 2013-10-24 | 2017-08-08 | 珠海格力电器股份有限公司 | Protection device for arc faults and its control method |
| CN104698040A (en) * | 2015-03-23 | 2015-06-10 | 滁州东润电子科技有限公司 | Water quality testing probe with TDS and temperature sensing functions |
| CN105067669A (en) * | 2015-06-30 | 2015-11-18 | 佛山市云米电器科技有限公司 | Detection circuit, detection apparatus and detection method |
| CN106053553A (en) * | 2016-07-26 | 2016-10-26 | 佛山科学技术学院 | Water quality monitor |
| CN109254326A (en) * | 2017-07-12 | 2019-01-22 | 美的智慧家居科技有限公司 | Water sensor and water sensor probe rust-proofing method |
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