CN110346015B - Electrode type water immersion detection circuit and water immersion sensor - Google Patents
Electrode type water immersion detection circuit and water immersion sensor Download PDFInfo
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- CN110346015B CN110346015B CN201910716928.2A CN201910716928A CN110346015B CN 110346015 B CN110346015 B CN 110346015B CN 201910716928 A CN201910716928 A CN 201910716928A CN 110346015 B CN110346015 B CN 110346015B
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- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 title claims abstract description 54
- 238000001514 detection method Methods 0.000 title claims abstract description 42
- 238000007654 immersion Methods 0.000 title claims abstract description 16
- 238000000819 phase cycle Methods 0.000 claims abstract description 5
- 239000003990 capacitor Substances 0.000 claims description 30
- HEZMWWAKWCSUCB-PHDIDXHHSA-N (3R,4R)-3,4-dihydroxycyclohexa-1,5-diene-1-carboxylic acid Chemical compound O[C@@H]1C=CC(C(O)=O)=C[C@H]1O HEZMWWAKWCSUCB-PHDIDXHHSA-N 0.000 claims description 28
- 238000006243 chemical reaction Methods 0.000 claims description 24
- 230000003750 conditioning effect Effects 0.000 claims description 5
- 230000007274 generation of a signal involved in cell-cell signaling Effects 0.000 claims description 4
- 230000002093 peripheral effect Effects 0.000 claims description 4
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- 239000000523 sample Substances 0.000 description 12
- 230000008901 benefit Effects 0.000 description 4
- 238000012544 monitoring process Methods 0.000 description 4
- 238000010586 diagram Methods 0.000 description 3
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- 238000007254 oxidation reaction Methods 0.000 description 2
- 230000003068 static effect Effects 0.000 description 2
- 229910000570 Cupronickel Inorganic materials 0.000 description 1
- 230000003321 amplification Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- YOCUPQPZWBBYIX-UHFFFAOYSA-N copper nickel Chemical compound [Ni].[Cu] YOCUPQPZWBBYIX-UHFFFAOYSA-N 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
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- 238000002791 soaking Methods 0.000 description 1
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Classifications
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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
- G01F23/22—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 measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water
- G01F23/24—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 measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water by measuring variations of resistance of resistors due to contact with conductor fluid
- G01F23/241—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 measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water by measuring variations of resistance of resistors due to contact with conductor fluid for discrete levels
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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
- G01F23/22—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 measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water
- G01F23/24—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 measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water by measuring variations of resistance of resistors due to contact with conductor fluid
- G01F23/241—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 measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water by measuring variations of resistance of resistors due to contact with conductor fluid for discrete levels
- G01F23/243—Schematic arrangements of probes combined with measuring circuits
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
- Y02A90/00—Technologies having an indirect contribution to adaptation to climate change
- Y02A90/30—Assessment of water resources
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- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Fluid Mechanics (AREA)
- General Physics & Mathematics (AREA)
- Measurement Of Current Or Voltage (AREA)
- Investigating Or Analyzing Materials By The Use Of Electric Means (AREA)
Abstract
The invention provides an electrode type water immersion detection circuit, which comprises: the first electrode signal input unit is used for converting and amplifying a first PWM signal received by the input end and is coupled with the first electrode through the output end; the second electrode signal input unit is used for converting and amplifying a second PWM signal received by the input end and is coupled with the second electrode through the output end; the first input end of the comparison unit is coupled with the first electrode, and the second input end of the comparison unit is coupled with a reference voltage signal and is used for comparing the voltage of the first electrode with the reference voltage signal; the input end of the signal output unit is coupled with the output end of the comparison unit and is used for amplifying the output signal of the comparison unit and outputting the output signal as a detection signal; the PWM signal input unit and the second electrode signal input unit output to the electrodes have the same period and pulse width, the phase sequence is 180 degrees different, and the signal duty ratio D is less than or equal to 5%. The circuit has high detection precision and long service life, and is suitable for equipment such as outdoor charging piles and the like.
Description
Technical Field
The invention relates to the field of sensing detection circuits, in particular to an electrode type water immersion detection circuit and a water immersion sensor.
Background
In a contact type water immersion sensor, a copper nickel plating probe is usually adopted, and a detection circuit judges whether water exists or not through voltage applied between the two probes. The existing contact type water immersion sensor has the advantages that a detection circuit is simple, a certain single-phase voltage is applied between two probes, electrodes are easy to corrode after water is detected for many times, and the service life is short. In addition, the interference voltage of the electrode is easy to cause the circuit damage of the detection part.
The Chinese patent (TDS detection circuit and detection method) (CN 103675023A) discloses a TDS detection circuit and detection method, wherein voltage is alternately loaded to two ends of a water quality probe to drive the water quality probe to work, so that electrolytic reaction caused by continuously loading direct-current voltage to the water quality probe is avoided, the detection precision of the water quality TDS is improved, the influence on water quality during detection is avoided, and the service life of the water quality probe is prolonged. However, the circuit disclosed in the patent has a simple structure, can not achieve ideal detection precision and service life, has poor anti-interference capability, and cannot be applied to equipment such as outdoor charging piles.
Disclosure of Invention
Based on the problems, the invention provides the electrode type water logging detection circuit and the water logging sensor which are high in detection precision, long in service life and suitable for equipment such as outdoor charging piles.
In order to achieve the above purpose, the invention adopts the following technical scheme:
a first aspect of the present invention provides an electrode type water logging detection circuit comprising:
The first electrode signal input unit is used for converting and amplifying a first PWM signal received by the input end and is coupled with the first electrode through the output end;
The second electrode signal input unit is used for converting and amplifying a second PWM signal received by the input end and is coupled with the second electrode through the output end;
The first input end of the comparison unit is coupled with the first electrode, and the second input end of the comparison unit is coupled with a reference voltage signal and is used for comparing the voltage of the first electrode with the reference voltage signal;
The input end of the signal output unit is coupled with the output end of the comparison unit, and is used for converting and amplifying the output signal of the comparison unit and outputting the output signal as a detection signal;
The PWM signal input unit and the second electrode signal input unit output to the electrodes have the same period and pulse width, the phase sequence is 180 degrees different, and the signal duty ratio D is less than or equal to 5%.
Further, the first electrode signal input unit comprises resistors R1-R3 and a MOS tube Q1; the drain electrode of the MOS tube Q1 is coupled with the first electrode, is coupled with a 9V voltage source through a resistor R3, the grid electrode is coupled with a first PWM signal source through the resistor R1, is coupled with the source electrode through a resistor R2, and is grounded;
The second electrode signal input unit comprises resistors R4-R6 and a MOS tube Q2; the drain electrode of the MOS transistor Q2 is coupled to the second electrode, and is coupled to a 9V voltage source through a resistor R6, the grid electrode is coupled to a second PWM signal source through a resistor R4, and is coupled to the source electrode through a resistor R5, and the source electrode is grounded.
Further, the comparison unit comprises a comparator U1 and resistors R7 and R8; the power end of the comparator U1 is coupled with a 9V voltage source, the inverting end is coupled with the first electrode, the non-inverting end is coupled with a reference voltage source, the non-inverting end is coupled with the 9V voltage source through a resistor R7 and is grounded through a resistor R8, and the output end is coupled with the signal output unit.
Further, the signal output unit comprises a MOS tube Q3, resistors R9-R11 and a capacitor C1; one end of the resistor R9 and the resistor R10 and one end of the capacitor C1 are coupled with a 9V voltage source, the other end of the resistor R9 is coupled with the output end of the comparison unit and the source electrode of the MOS tube Q3, the other end of the resistor R10 is coupled with the grid electrode of the MOS tube Q3, and the drain electrode of the MOS tube Q3 is coupled with the voltage source VCC through the resistor R11 and used as an output end to output a detection signal.
Further, the detection circuit further comprises an electrode protection unit, the electrode protection unit comprises transient voltage suppression diodes D1 and D2, wherein anodes of the diodes D1 and D2 are coupled to ground oppositely, and cathodes of the diodes are coupled to the first electrode and the second electrode respectively.
A second aspect of the present invention provides a water logging sensor comprising two electrodes, an electrode water logging detection circuit as described in the first aspect above coupled to the electrodes, further comprising:
And a signal generation circuit for generating the first PWM signal and the second PWM signal.
Preferably, the signal generating circuit comprises an integrated MCU packaged by SOP8 and peripheral circuits thereof.
Further, the water immersion sensor further includes:
The power supply circuit comprises a first DCDC conversion step-down circuit and a second DCDC conversion step-down circuit which are identical in structure and independent of each other, wherein the first DCDC conversion step-down circuit is used for providing stable 9.0V voltage, and the second DCDC conversion step-down circuit is used for providing stable 3.3V voltage.
Further, the first DCDC conversion step-down circuit comprises resistors R13-R19, capacitors C2-C11, a DCDC chip U2 and an inductor L1; the VIN pin of the DCDC chip U2 is coupled with the input power supply VDDIN and grounded through capacitors C2, C3 and C4; the EN pin is coupled with the VIN pin through a resistor R13 and is grounded through a resistor R14; the RT pin is grounded through a resistor R15; the BOOT pin is coupled with one end of the capacitor C5, and the PH pin and the other end of the capacitor C5 are coupled with one end of the inductor L1; the COMP pin is grounded through a resistor R16, a capacitor C11 and a capacitor C10 which are connected in series respectively; GND pin is grounded; the other end of the inductor L1 is grounded through capacitors C6, C7 and C8 and resistors R17, R18 and R19 which are connected in series respectively and is used as a power supply output end; the capacitor C9 is connected in parallel to both ends of the resistor R19.
Further, the power supply circuit further comprises a conditioning protection circuit, wherein the conditioning protection circuit comprises a diode D3, a fuse F1, a piezoresistor R12 and an anti-surge TVS tube D4; the positive electrode of the diode D3 is coupled to an external power source, and the negative electrode of the diode D is coupled to the fuse F1, and then is used as an output terminal to output the voltage VDDIN, and is grounded through the varistor R12 and the anti-surge TVS tube D4, respectively.
The invention has the beneficial effects that:
According to the electrode type water logging detection circuit and the water logging sensor, PWM signals with the same signal period and pulse width and 180-degree phase sequence difference are applied to the two electrodes, so that positive and negative directions of current on the water logging test electrodes flow in a staggered mode, and oxidation of the electrodes is effectively prevented. Meanwhile, the duty ratio D of the PWM signals output to the electrodes through MOS tube driving amplification is less than or equal to 5%, so that the power consumption of the device can be effectively reduced, and the detection precision of the circuit is improved. In addition, by reasonably setting the comparison and result output circuit, the wider comparison monitoring capability is realized; by setting the comparison threshold value, the water immersion monitoring alarm capacity under the condition of low TDS can be realized, so that the monitoring capacity of rain water immersion under the outdoor condition is satisfied. Finally, in view of the complex internal environment of the equipment such as the outdoor charging pile, the circuit is provided with the electrode protection circuit, the power supply protection circuit, the level conversion circuit and the like in order to prevent unpredictable complex electromagnetic environment such as static electricity, and the anti-interference capability of the circuit is improved to the greatest extent, so that the stability of the circuit is improved.
Drawings
FIG. 1 is a schematic diagram of the unit composition and connection relationship of the electrode type water immersion detection circuit of the present invention.
Fig. 2 is a schematic circuit diagram of an embodiment of an electrode type water immersion detection circuit according to the present invention.
FIG. 3 is a schematic circuit diagram of a power circuit in an embodiment of the water sensor of the present invention.
Detailed Description
For a further understanding of the present invention, preferred embodiments of the invention are described below in conjunction with the examples, but it should be understood that these descriptions are merely intended to illustrate further features and advantages of the invention, and are not limiting of the claims of the invention.
Example 1
A first embodiment of the present invention provides an electrode type water logging detection circuit, as shown in fig. 1, comprising:
The first electrode signal input unit is used for converting and amplifying a first PWM signal received by the input end and is coupled with the first electrode through the output end;
The second electrode signal input unit is used for converting and amplifying a second PWM signal received by the input end and is coupled with the second electrode through the output end;
The first input end of the comparison unit is coupled with the first electrode, and the second input end of the comparison unit is coupled with a reference voltage signal and is used for comparing the voltage of the first electrode with the reference voltage signal;
The input end of the signal output unit is coupled with the output end of the comparison unit, and is used for converting and amplifying the output signal of the comparison unit and outputting the output signal as a detection signal;
The PWM signals output to the electrodes by the first electrode signal input unit and the second electrode signal input unit have the same period and pulse width, the phase sequence is 180 degrees different, and the signal duty ratio D is less than or equal to 5%.
The electrode type water logging detection circuit in this example will be further described with reference to the preferred embodiment shown in fig. 2.
In this embodiment, as shown in fig. 2, the first electrode signal input unit includes resistors R1-R3 and a MOS transistor Q1; the drain electrode of the MOS tube Q1 is coupled with the first electrode, is coupled with a 9V voltage source through a resistor R3, the grid electrode is coupled with a first PWM signal source through the resistor R1, is coupled with the source electrode through a resistor R2, and is grounded;
The second electrode signal input unit comprises resistors R4-R6 and a MOS tube Q2; the drain electrode of the MOS transistor Q2 is coupled to the second electrode, and is coupled to a 9V voltage source through a resistor R6, the grid electrode is coupled to a second PWM signal source through a resistor R4, and is coupled to the source electrode through a resistor R5, and the source electrode is grounded.
The comparison unit comprises a comparator U1 and resistors R7 and R8; the power end of the comparator U1 is coupled with a 9V voltage source, the inverting end is coupled with the first electrode, the non-inverting end is coupled with a reference voltage source, the non-inverting end is coupled with the 9V voltage source through a resistor R7 and is grounded through a resistor R8, and the output end is coupled with the signal output unit.
The signal output unit comprises a MOS tube Q3, resistors R9-R11 and a capacitor C1; one end of the resistor R9 and the resistor R10 and one end of the capacitor C1 are coupled with a 9V voltage source, the other end of the resistor R9 is coupled with the output end of the comparison unit and the source electrode of the MOS tube Q3, the other end of the resistor R10 is coupled with the grid electrode of the MOS tube Q3, and the drain electrode of the MOS tube Q3 is coupled with the voltage source VCC through the resistor R11 and used as an output end to output a detection signal.
As a further preferred embodiment, the detection circuit in this example further comprises an electrode protection unit, which includes transient voltage suppression diodes D1 and D2, wherein the anodes of the diodes D1 and D2 are coupled to ground in opposition, and the cathodes are coupled to the first electrode and the second electrode, respectively.
The working principle of the circuit is as follows: the first electrode and the second electrode receive two groups of PWM pulse signals PWM1 and PWM2 with fixed duty ratio output by the singlechip in a push-pull output mode, the pulse period is 1S, the duty ratio is 95%, and the two groups of pulse signals are 180 degrees different in phase. When the PWM1 outputs high level, after the current is limited by the R1 resistor, the driving MOS tube Q1 is conducted, the end of the PWMC1 is pulled down to be in a low level state, namely the PWM1 inputs high level, and the corresponding PWMC1 outputs low level; PWM1 inputs a low level and outputs a high level corresponding to PWMC 1. Thus, PWMC1 and PWMC2 are a set of pulse signals 180 degrees out of phase, and since the drains of MOS transistors Q1 and Q2 are both 9V, the PWMC1 and PWMC2 signals are pulse sequences 9V in amplitude, 5% in duty cycle, and 180 degrees out of phase. The pulse sequence is applied to the electrode probe, and under the condition of water conduction, the current direction is the flow in an alternating direction, so that the ionization of the water body electrolyte caused by the unipolar current flow is reduced, and the oxidation of the probe is caused. Transient voltage suppression diodes (TVS) D1, D2 are responsible for absorbing static and surge signals on the probes. R7 and R8 form a resistive divider circuit that clamps the voltage at Vst at 8.18V as the base threshold voltage signal for comparator U1. Under the condition that the probe is not contacted with water, the amplitude of the PWMC1 signal is 9V, and after the signal passes through the comparator, the voltage signal on the output pin of the comparator U1 is a pulse signal with the duty ratio of 95%. If the water quality is conductive, so that the PWMC1 and the PWMC2 are conducted, the voltage of the PWMC1 is reduced along with the rise of the TDS value of the water quality, and when the voltage signal of the PWMC1 is pulled down to a certain degree, the output pin of the comparator U1 completely outputs a high level. R10, R11 and Q3 form a level conversion circuit module, when the output pin of the comparator U1 outputs high level 9V, Q3 does not work, and the drain electrode thereof is provided with a TEST_OUT output voltage signal with the amplitude of 3.3V; when the output pin of U1 outputs low level 0V, Q3 works, and the drain electrode thereof outputs low level signal with amplitude lower than 0.5V. Therefore, the subsequent singlechip can judge whether water with the TDS value larger than a certain limit value exists at the probe by judging the level characteristic of the TEST_OUT signal, so that whether water soaking occurs is finally judged.
Example 2
A second embodiment of the present invention provides a water logging sensor, comprising two electrodes, an electrode-type water logging detection circuit as described in the first embodiment above coupled to the electrodes, further comprising:
A signal generation circuit for generating the first PWM signal and the second PWM signal;
The power supply circuit comprises a first DCDC conversion step-down circuit and a second DCDC conversion step-down circuit which are identical in structure and independent from each other, wherein the first DCDC conversion step-down circuit is used for providing stable 9.0V voltage for the operation of the subsequent water immersion monitoring circuit and the status indication output; the second DCDC conversion step-down circuit is used for providing stable 3.3V voltage for the stable and reliable work of the later-stage MCU part.
In this example, the signal generating circuit includes an integrated MCU packaged by SOP8 and its peripheral circuits, and has the advantages of less peripheral circuits, convenient program loading and debugging, stable operation, and good economic benefit.
As a preferred embodiment, as shown in fig. 3, in this example, the first DCDC conversion step-down circuit includes resistors R13 to R19, capacitors C2 to C11, a DCDC chip U2, and an inductor L1; the VIN pin of the DCDC chip U2 is coupled with the input power supply VDDIN and grounded through capacitors C2, C3 and C4; the EN pin is coupled with the VIN pin through a resistor R13 and is grounded through a resistor R14; the RT pin is grounded through a resistor R15; the BOOT pin is coupled with one end of the capacitor C5, and the PH pin and the other end of the capacitor C5 are coupled with one end of the inductor L1; the COMP pin is grounded through a resistor R16, a capacitor C11 and a capacitor C10 which are connected in series respectively; GND pin is grounded; the other end of the inductor L1 is grounded through capacitors C6, C7 and C8 and resistors R17, R18 and R19 which are connected in series respectively, and is used as a power supply output end to output DVDD9.0V voltage; the capacitor C9 is connected in parallel to both ends of the resistor R19.
In this embodiment, the structure of the second DCDC conversion step-down circuit is identical to that of the first DCDC conversion step-down circuit, and the output terminal outputs VCC3.3V voltages, which are not described herein.
As a further preferred embodiment, in this example, the power supply circuit further includes a conditioning protection circuit including a diode D3, a fuse F1, a varistor R12, and an anti-surge TVS tube D4; the positive electrode of the diode D3 is coupled to an external power source, and the negative electrode of the diode D is coupled to the fuse F1, and then is used as an output terminal to output the voltage VDDIN, and is grounded through the varistor R12 and the anti-surge TVS tube D4, respectively.
In this embodiment, the first DCDC conversion step-down circuit and the second DCDC conversion step-down circuit adopt single-point grounding, and are independent as far as possible on the circuit layout and the circuit routing, so that mutual interference from the power supply ground is reduced to the maximum extent, and the anti-interference capability of the circuit is effectively improved. The diode D3, the fuse F1, the piezoresistor R12 and the anti-surge TVS tube D4 form a conditioning protection circuit of the input power supply part. Wherein, D3 is used for preventing reverse connection of the diode, so that the circuit is not damaged when the power supply inputs positive and negative errors; the F1 self-recovery fuse is used for providing instantaneous protection when a later-stage circuit is in an instantaneous short circuit or other reasons; r12 and D4 form a surge protection circuit, and are conducted in a fast and slow mode, so that the influence on the circuit when surge impact occurs is effectively prevented. The DCDC chip U2 is a high-efficiency synchronous DCDC conversion chip with functions of overvoltage, undervoltage, overcurrent, overheat protection, soft start and the like, wherein VIN is a high-voltage input of the chip, VSENSE is a feedback input of the chip, EN is an enabling and starting control input of the chip, COMP is an external compensation input of the chip, and PH is a DCDC conversion output of the chip.
The above description of the embodiments is only for aiding in the understanding of the method of the present invention and its core ideas. It should be noted that it will be apparent to those skilled in the art that various modifications and adaptations of the invention can be made without departing from the principles of the invention and these modifications and adaptations are intended to be within the scope of the invention as defined in the following claims.
Claims (10)
1. An electrode-type water immersion detection circuit, comprising:
The first electrode signal input unit is used for converting and amplifying a first PWM signal received by the input end and is coupled with the first electrode through the output end;
The second electrode signal input unit is used for converting and amplifying a second PWM signal received by the input end and is coupled with the second electrode through the output end;
The first input end of the comparison unit is coupled with the first electrode, and the second input end of the comparison unit is coupled with a reference voltage signal and is used for comparing the voltage of the first electrode with the reference voltage signal;
The input end of the signal output unit is coupled with the output end of the comparison unit, and is used for converting and amplifying the output signal of the comparison unit and outputting the output signal as a detection signal;
The PWM signal input unit and the second electrode signal input unit output to the electrodes have the same period and pulse width, the phase sequence is 180 degrees different, and the signal duty ratio D is less than or equal to 5%.
2. The electrode type water logging detection circuit according to claim 1, wherein the first electrode signal input unit comprises resistors R1-R3 and a MOS tube Q1; the drain electrode of the MOS tube Q1 is coupled with the first electrode, is coupled with a 9V voltage source through a resistor R3, the grid electrode is coupled with a first PWM signal source through the resistor R1, is coupled with the source electrode through a resistor R2, and is grounded;
The second electrode signal input unit comprises resistors R4-R6 and a MOS tube Q2; the drain electrode of the MOS transistor Q2 is coupled to the second electrode, and is coupled to a 9V voltage source through a resistor R6, the grid electrode is coupled to a second PWM signal source through a resistor R4, and is coupled to the source electrode through a resistor R5, and the source electrode is grounded.
3. The electrode type water logging detection circuit of claim 1 wherein the comparison unit comprises a comparator U1 and resistors R7, R8; the power end of the comparator U1 is coupled with a 9V voltage source, the inverting end is coupled with the first electrode, the non-inverting end is coupled with a reference voltage source, the non-inverting end is coupled with the 9V voltage source through a resistor R7 and is grounded through a resistor R8, and the output end is coupled with the signal output unit.
4. The electrode type water logging detection circuit according to claim 1, wherein the signal output unit comprises a MOS tube Q3, resistors R9-R11 and a capacitor C1; one end of the resistor R9 and the resistor R10 and one end of the capacitor C1 are coupled with a 9V voltage source, the other end of the resistor R9 is coupled with the output end of the comparison unit and the source electrode of the MOS tube Q3, the other end of the resistor R10 is coupled with the grid electrode of the MOS tube Q3, and the drain electrode of the MOS tube Q3 is coupled with the voltage source VCC through the resistor R11 and used as an output end to output a detection signal.
5. The electrode type water logging detection circuit of any one of claims 1 to 4 further comprising an electrode protection unit comprising transient voltage suppressing diodes D1 and D2, wherein the anodes of the diodes D1 and D2 are coupled to ground in opposition and the cathodes are coupled to the first electrode and the second electrode, respectively.
6. A water logging sensor comprising two electrodes, the electrode-type water logging detection circuit of any one of claims 1-5 coupled to the electrodes, further comprising:
And a signal generation circuit for generating the first PWM signal and the second PWM signal.
7. The water sensor of claim 6, wherein the signal generation circuit comprises an SOP8 packaged integrated MCU and its peripheral circuitry.
8. The water logging sensor of claim 6 or 7 further comprising:
The power supply circuit comprises a first DCDC conversion step-down circuit and a second DCDC conversion step-down circuit which are identical in structure and independent of each other, wherein the first DCDC conversion step-down circuit is used for providing stable 9.0V voltage, and the second DCDC conversion step-down circuit is used for providing stable 3.3V voltage.
9. The water sensor of claim 8, wherein the first DCDC conversion step-down circuit comprises resistors R13-R19, capacitors C2-C11, DCDC chip U2, and inductor L1; the VIN pin of the DCDC chip U2 is coupled with the input power supply VDDIN and grounded through capacitors C2, C3 and C4; the EN pin is coupled with the VIN pin through a resistor R13 and is grounded through a resistor R14; the RT pin is grounded through a resistor R15; the BOOT pin is coupled with one end of the capacitor C5, and the PH pin and the other end of the capacitor C5 are coupled with one end of the inductor L1; the COMP pin is grounded through a resistor R16, a capacitor C11 and a capacitor C10 which are connected in series respectively; GND pin is grounded; the other end of the inductor L1 is grounded through capacitors C6, C7 and C8 and resistors R17, R18 and R19 which are connected in series respectively and is used as a power supply output end; the capacitor C9 is connected in parallel to both ends of the resistor R19.
10. The water sensor of claim 8, wherein the power circuit further comprises a conditioning protection circuit comprising a diode D3, a fuse F1, a varistor R12, and an anti-surge TVS tube D4; the positive electrode of the diode D3 is coupled to an external power source, and the negative electrode of the diode D is coupled to the fuse F1, and then is used as an output terminal to output the voltage VDDIN, and is grounded through the varistor R12 and the anti-surge TVS tube D4, respectively.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201910716928.2A CN110346015B (en) | 2019-08-05 | 2019-08-05 | Electrode type water immersion detection circuit and water immersion sensor |
Applications Claiming Priority (1)
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| CN117311229B (en) * | 2023-10-23 | 2024-04-26 | 国网河北省电力有限公司雄安新区供电公司 | Intelligent micro-control system for water immersion sensor and control method thereof |
| CN118640989B (en) * | 2024-08-15 | 2024-10-22 | 四川芯音科技有限公司 | A MEMS high-precision liquid level detection sensor |
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