CN111649800A - Water level automatic detection and control method based on digital logic circuit - Google Patents

Water level automatic detection and control method based on digital logic circuit Download PDF

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Publication number
CN111649800A
CN111649800A CN202010584073.5A CN202010584073A CN111649800A CN 111649800 A CN111649800 A CN 111649800A CN 202010584073 A CN202010584073 A CN 202010584073A CN 111649800 A CN111649800 A CN 111649800A
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water level
schmitt trigger
water
voltage
signal
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许亮
许太安
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Zaozhuang University
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Zaozhuang University
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
    • G01F23/00—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm
    • G01F23/14—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measurement of pressure
    • G01F23/18—Indicating, recording or alarm devices actuated electrically
    • G01F23/185—Indicating, recording or alarm devices actuated electrically for discrete levels

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  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • General Physics & Mathematics (AREA)
  • Measurement Of Levels Of Liquids Or Fluent Solid Materials (AREA)

Abstract

The invention discloses a water level detection and control method, which utilizes the upper and lower limit threshold voltages of a Schmidt trigger to correspondingly detect the water levels of an upper line and a lower line of a container, so that water injection is stopped when the water level reaches the upper limit, and water injection is automatically performed when the water level is lower than the lower limit.

Description

Water level automatic detection and control method based on digital logic circuit
Technical Field
The invention belongs to the technical field of automatic water level detection and supplement, and particularly relates to a method for realizing automatic water level detection and supplement based on a digital logic circuit.
Background
In the fields of current industrial production, aquaculture or high-rise building living water supply and the like, a water tank or a container for storing industrial reagents is often required to be subjected to real-time water level detection, and water is injected when the water level is lower than the lowest water level line so as to maintain the water level within a certain height range. Currently, with the development of electronic technology, a water level maintenance system that automatically monitors and automatically injects water has been implemented, but it is still unsatisfactory. Firstly, the cost is not low enough; secondly, when the water level of the water tank or the fish pond needs to be changed along with the change of production data or aquaculture data, the water tank or the fish pond needs to be drained firstly, and then a sampling switch device such as a sensor and the like in the water tank or the fish pond needs to be changed in installation height according to the requirements of the water level of the water tank or the fish pond, which is troublesome in the application of some large water tanks or fish ponds.
Disclosure of Invention
Aiming at the problems, the invention provides a real-time water level detection and control circuit and a design method thereof, which realize the detection and automatic maintenance of the upper and lower line water levels of a detected container by skillfully setting the upper and lower line threshold voltages of a Schmitt trigger in the digital logic electronic technology, and have low cost and extremely low power consumption; meanwhile, when the upper and lower line water levels of the detected water tank or container need to be adjusted, corresponding matching of new upper and lower line water levels can be conveniently realized only by simply replacing the resistor in the Schmidt trigger, the water tank does not need to be drained, and the use is convenient.
In order to achieve the purpose, the technical scheme adopted by the invention is as follows:
a water level detection and control method comprises a water pressure sensor, a Schmidt trigger, an electric switch, a water pump or a water gate loop, wherein the water pressure sensor is arranged at the bottom of a detection water tank or a container so as to convert water pressure change caused by water level change into corresponding voltage signals to be output; the signal input end of the Schmitt trigger is connected with a signal wire of the water pressure sensor, the upper and lower limit threshold voltages are set as corresponding output signal voltages when the water pressure sensor is positioned at the upper limit value and the lower limit value, and the signal output end of the Schmitt trigger is connected with the electric switch to control the on or off of the electric switch; the electric switch is connected in series in a loop of the water pump or the sluice; the Schmidt trigger and the electric switch are both arranged outside the water tank.
Further, the signal input end of the schmitt trigger is connected with a signal line of the water pressure sensor, the signal input end of the schmitt trigger can be connected with a signal line of a voltage output type water pressure sensor which outputs a voltage signal, and the signal input end of the schmitt trigger can be connected with a sampling voltage line of a resistor which is connected with the current output type water pressure sensor which outputs a current signal and is connected with a sampling resistor in series.
Further, the schmitt trigger is a schmitt trigger composed of basic CMOS gate circuits, that is, the schmitt trigger is composed of two not gates and two resistors, a first resistor is connected in series with an input end of a first not gate, an input end of a second not gate is connected with an output end of the first not gate, one end of the second resistor is connected with the input end of the first not gate, the other end of the second resistor is connected with an output end of the second not gate, the input end of the first not gate is used as the input end of the schmitt trigger through a lead led out from the first resistor connected in series, and the output end of the second not gate is used as the output end of the schmitt trigger.
Furthermore, the method for setting the upper and lower threshold voltages of the schmitt trigger comprises the following steps: when the water level is at the upper line water level and the lower line water level, the corresponding output signal voltages are respectively VT+And VT-Setting the internal NOT threshold voltage V of the Schmitt triggerTHHas a value of (V)T++VT-) V, supply voltage V by means of Schmitt triggerDDAnd VTHThe arithmetic relation V betweenDD=2VTHCalculate VDDResistance R1/R2The ratio is set to (V)T++VT-)/2VTHAt this time, the values of the upper and lower threshold voltages corresponding to the schmitt trigger are the required set values.
Further, the electric switch is a relay.
By adopting the technical scheme, the invention can monitor the water level in real time and enable the water level to be positioned between the upper line water level and the lower line water level; the circuit structure is simple, so that the reliability is high, the use is convenient, the cost is low, the cost of the current water pressure sensor is usually dozens of yuan or dozens of yuan, and the price of the Schmidt trigger is usually about several yuan; and the water level heights of the upper line and the lower line can be conveniently set by a method of switching resistors, and the position adjustment of the sensor by a draining container is not required like a common water level automatic detection and supplement system.
Drawings
Fig. 1 is a schematic structural diagram of the technical solution of the present invention.
Fig. 2 is a schematic diagram of one of schmitt triggers used in the present invention.
In the attached drawing, 1-water tank, 2-water pressure sensor, 3-Schmidt trigger, 4-electric switch, 5-water pump or water gate, G1 and G2 are CMOS inverters.
Detailed Description
Referring to fig. 1, the basic working principle of the technical scheme of the present invention is as follows: the water pressure sensor 2 converts the water pressure in the water tank 1 into corresponding voltage signals to be output, a signal line of the water pressure sensor is connected to the input end of the Schmidt trigger 3, and the upper and lower limit threshold voltages of the Schmidt trigger 3 are set to be the voltages corresponding to the water pressure sensor 2 when the water level is located at the upper limit value and the lower limit value. When the water level in the water tank 1 is lower than the off-line water level, the output voltage of the water pressure sensor 2 is lower than the lower limit threshold voltage of the Schmidt trigger 3, at the moment, the Schmidt trigger 3 outputs high voltage '1', an electric switch 4 connected with the output end of the Schmidt trigger 3 is started, a loop of the water pump or a water gate 5 is conducted, the water pump is started to inject water into the water tank 1 or the water gate is opened to inject water into the water tank 1, and the water level of the water tank 1 rises. When the water level in the water tank 1 rises between the upper line water level and the lower line water level, the output voltage of the water pressure sensor 2 is positioned between the upper limit threshold voltage and the lower limit threshold voltage of the Schmidt trigger 3, so the output of the Schmidt trigger 3 is still high voltage '1', and a water pump or a water gate 5 loop is kept conducted, so the water level continues rising. When the water level rises to the upper line water level, the output voltage of the water pressure sensor 2 reaches the upper limit threshold voltage of the Schmidt trigger 3, the Schmidt trigger 3 outputs low voltage of 0, and the water injection is finished. By analogy, when the water level is lowered to a position between the upper line water level and the lower line water level, the Schmidt trigger 3 still outputs low voltage '0', and water cannot be filled into the water tank 1. When the water level in the water tank 1 is lower than the off-line water level, the output voltage of the water pressure sensor 2 is lower than the lower threshold voltage of the Schmidt trigger 3, at the moment, the Schmidt trigger 3 outputs high voltage '1' again, and water injection is restarted.
More specifically, for example, in the present embodiment, when the corresponding voltage of the water level of the upper line and the water level of the lower line of the water pressure sensor 2 is 6V or 8V, the parameters of the schmitt trigger 3 are set as follows: vT+= (1+ R1/R2) VTH=8V；VT-= (1- R1/R2) VTH=6V, usually WTH≈VDDV of Schmitt trigger 3 in this embodiment can be setTH=7V, return difference voltage Δ VT=VT+-VT-=8-6=2V, from the basic knowledge of the schmitt trigger of the present embodiment, i.e. 2R1VTH/R2=2V，R1/R2=1/7, at this time, the setting of the threshold voltage can be completed. If the water level of the upper line and the lower line needs to be changed, for example, the water level is changed to be corresponding to the water level when the output voltage of the water pressure sensor 2 is 9V or 6V, V isTH=7.5V, R1/R2= 1/5.
The above is one method for setting the upper and lower threshold voltages of the schmitt trigger 3 based on the CMOS gate circuit in this embodiment, but the threshold voltage of the schmitt trigger 3 can be conveniently set without adopting the above setting method, which is common knowledge of those skilled in the art, so the setting method is not considered as a limitation to the contents of the invention, and the setting of the threshold voltage of the schmitt trigger 3 by adopting other methods should not be considered as a destruction to the creativity of the present invention.
In addition, even if the setting method is simply applied, V is not involved when the upper and lower line water levels are resetTHWhen the voltage corresponding to the water level of the upper and lower lines is changed from 8V and 6V to 8.5V and 5.5V, respectively, only R needs to be changed1/R2The ratio is obtained; if it relates to VTHVariations of (e.g. [0014 ]]When the water level is changed, a slide rheostat can be connected in series with the power supply, and the V of the Schmitt trigger can be adjusted by rotating a knobDDTo achieve regulation of VTHPurpose of (1), but other methods of altering V may be usedDD， VDDThe voltage change is the simplest and simplest common knowledge in the circuit, so that V is changed by adopting other methodsDDThe voltage belongs to the technical scheme of the invention. In addition, because of VDDIs given a value of VTH≈V DD2 instead of VTH=V DD2, therefore for certain VTHAnd VDDThe Schmitt trigger with slight variation is firstly finely adjusted by sliding a rheostat knob before use, so that the matching precision of the water levels of the upper line and the lower line of the Schmitt trigger is ensured.
In the embodiment, the water pressure sensor 2 is of a current output type, and is powered by 12V-36V, outputs signal current of 4-20mA, connects the output current to a resistor with proper resistance value for voltage sampling, and then connects a signal wire of the sampled voltage to the input end of the Schmidt trigger 3. Wherein, proper resistance means that the sampling voltage of the sampling resistor with the resistance value is matched with the range of the input voltage of the Schmitt trigger 3. In the embodiment, the water pressure sensor 2 is powered by a 36V power supply, and the power supply V of the Schmidt trigger 3DDThe 36V power supply is connected in series with a slide rheostat for voltage division so as to conveniently adjust the VDD。
In this embodiment, the water pressure sensor 2 can also be directly used as a voltage output type, the signal voltage output range of the used water pressure sensor 2 is 0-10V, the measuring range is 0-1MPa, and the voltage signal line is directly connected with the input end of the schmitt trigger 3. However, due to the variety of applications in actual production and life, the voltage output range may not match the input voltage range of the schmitt trigger 3, and in this case, a voltage amplifying circuit or a voltage dividing resistor may be used to divide and extract the voltage as the signal line.
The above are merely preferred embodiments of the present invention, and are not intended to limit the present invention. Various modifications and alterations to this invention will become apparent to those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (5)

1. A water level detection and control method is characterized in that: the water pressure sensor is arranged at the bottom of a detection water tank or a container so as to convert water pressure change caused by water level change into corresponding voltage signals to be output; the signal input end of the Schmidt trigger is connected with a signal wire of the water pressure sensor, the upper limit threshold voltage and the lower limit threshold voltage of the Schmidt trigger are respectively set as output signal voltages corresponding to the water pressure sensor when the water level is at the upper limit value and the lower limit value, and the signal output end of the Schmidt trigger is connected with the electric switch to control the on or off of the electric switch; the electric switch is connected in series in a loop of the water pump or the sluice; the Schmidt trigger and the electric switch are both arranged outside the water tank.
2. The water level detecting and controlling method as claimed in claim 1, wherein:
the signal input end of the Schmitt trigger is connected with a signal line of the water pressure sensor, the signal input end of the Schmitt trigger can be connected with a signal line of a voltage output type water pressure sensor which outputs a voltage signal, and the signal input end of the Schmitt trigger can also be connected with a sampling voltage line of a resistor which is connected with a current output type water pressure sensor which outputs a current signal in series with a sampling resistor.
3. The water level detecting and controlling method as claimed in claim 1, wherein:
the Schmitt trigger is a Schmitt trigger composed of basic CMOS gate circuits, namely the Schmitt trigger is composed of two NOT gates and two resistors, wherein the first resistor is connected in series with the input end of the first NOT gate, the input end of the second NOT gate is connected with the output end of the first NOT gate, one end of the second resistor is connected with the input end of the first NOT gate, the other end of the second resistor is connected with the output end of the second NOT gate, the input end of the first NOT gate is used as the input end of the Schmitt trigger through a lead led out from the first resistor connected in series, and the output end of the second NOT gate is used as the output end of the Schmitt trigger.
4. The water level detecting and controlling method as claimed in claim 3, wherein: the method for setting the upper and lower limit threshold voltages of the Schmitt trigger comprises the following steps: when the water level is at the upper line water level and the lower line water level, the corresponding output signal voltages are respectively VT+And VT-Setting the internal NOT threshold voltage V of the Schmitt triggerTHHas a value of (V)T++VT-) V, supply voltage V by means of Schmitt triggerDDAnd VTHThe arithmetic relation V betweenDD=2VTHCalculate VDDResistance R1/R2The ratio is set to (V)T++VT-)/2VTHAt this time, the values of the upper and lower threshold voltages corresponding to the schmitt trigger are the required set values.
5. The water level detecting and controlling method as claimed in claim 1, wherein: the electric switch is a relay.
CN202010584073.5A 2020-06-24 2020-06-24 Water level automatic detection and control method based on digital logic circuit Withdrawn CN111649800A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114001795A (en) * 2021-11-01 2022-02-01 国网北京市电力公司 Liquid level monitoring method and device, computer readable medium and processor

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CN206833262U (en) * 2017-06-09 2018-01-02 深圳市盛孚物业管理股份有限公司 Cell cistern water level automatically controls and warning system
CN209416446U (en) * 2018-11-30 2019-09-20 深圳和而泰小家电智能科技有限公司 A kind of water level detection circuit and electrical equipment

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CN105068568A (en) * 2015-08-12 2015-11-18 成都易思科科技有限公司 Control circuit having liquid detection function
CN204856234U (en) * 2015-08-12 2015-12-09 成都易思科科技有限公司 Control circuit with liquid detects function
CN205228582U (en) * 2015-10-22 2016-05-11 天津盛世龙源科技有限公司 Liquid level detection system among sewage treatment
CN206833262U (en) * 2017-06-09 2018-01-02 深圳市盛孚物业管理股份有限公司 Cell cistern water level automatically controls and warning system
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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114001795A (en) * 2021-11-01 2022-02-01 国网北京市电力公司 Liquid level monitoring method and device, computer readable medium and processor
CN114001795B (en) * 2021-11-01 2023-11-03 国网北京市电力公司 Liquid level monitoring method, liquid level monitoring device, computer readable medium and processor

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Application publication date: 20200911