CN217304082U - Liquid level measuring device - Google Patents

Abstract

The utility model relates to a level gauge technical field especially relates to a measure liquid level device, and it includes: the circuit comprises a capacitance module, a counting circuit, a timing circuit, an RC oscillating circuit, a filter circuit and an amplifying circuit; the capacitance module is used for providing a capacitance dynamic signal; the timing circuit is connected with the capacitor module and used for converting the received capacitor dynamic signal into a pulse signal frequency change; the counting circuit is connected with the timing circuit and is used for outputting a high-frequency pulse signal to the timing circuit; the RC oscillating circuit is connected with the timing circuit and used for carrying out frequency conversion on the carrier signal to generate a low-frequency pulse signal; the filter circuit is connected with the RC oscillating circuit and is used for filtering clutter in a low-frequency pulse signal output by the RC oscillating circuit; and the amplifying circuit is used for amplifying the low-frequency pulse signal with the clutter filtered. This application has the effect that improves liquid level measurement's accuracy.

Description

Liquid level measuring device

Technical Field

The application relates to the technical field of liquid level meters, in particular to a liquid level measuring device.

Background

A liquid level meter is widely used in the industrial field as a liquid measuring device, and nowadays, the liquid level meter for measuring a liquid position is of various types including a pressure type, an ultrasonic type, a sonar type, a radar type, and a capacitance type.

The traditional capacitance type liquid level meter has the principle that the contact area of insulating liquid and an electrode plate is changed, so that the contact area of the electrode plate of a capacitor is changed, the liquid level variation of the liquid is converted into the capacitance variation in a capacitor, and the liquid level of the liquid is determined by detecting the dynamic voltage released by the capacitor.

However, when the liquid level condition is detected by using a capacitor, the dielectric constant of the liquid is changed under the influence of the field environment, which affects the stability of the dynamic signal output by the capacitor, so that the dynamic signal output by the capacitor as an index for judging the liquid level condition becomes inaccurate.

SUMMERY OF THE UTILITY MODEL

In order to improve the accuracy of level measurement, this application provides a measure liquid level device.

The application provides a measure liquid level device adopts following technical scheme:

a liquid level measuring device comprises a capacitance module, a counting circuit, a timing circuit, an RC oscillating circuit, a filter circuit and an amplifying circuit;

the capacitance module is used for providing a capacitance dynamic signal;

the timing circuit is connected with the capacitor module and used for converting the received capacitor dynamic signal into a pulse signal frequency change;

the counting circuit is connected with the timing circuit and is used for outputting a high-frequency pulse signal to the timing circuit;

the RC oscillating circuit is connected with the timing circuit and used for carrying out frequency conversion on the carrier signal to generate a low-frequency pulse signal;

the filter circuit is connected with the RC oscillating circuit and is used for filtering clutter in a low-frequency pulse signal output by the RC oscillating circuit;

and the amplifying circuit is used for amplifying the low-frequency pulse signal of which the clutter is filtered.

By adopting the technical scheme, the capacitance in the capacitor changes along with the change of the contact area between the electrode plates, and the capacitor dynamic signal is released to the timing circuit; meanwhile, the timing circuit receives the high-frequency signal output by the counting circuit, superposes the high-frequency pulse signal and the capacitance dynamic signal, and finally outputs a carrier pulse signal to the RC oscillating circuit; the RC oscillating circuit carries out frequency conversion on the high-frequency carrier signal to output a low-frequency signal, then the low-frequency signal is filtered through the filter circuit, clutter signals in the signal processing process of the timing circuit and the RC oscillating circuit are filtered, the fixed-frequency signal without the clutter signals is amplified through the amplifying circuit, and finally a required pulse signal is output.

Optionally, the liquid level detection device further includes a power supply circuit, and the power supply circuit includes: diode D1, diode D2, diode D3, capacitor C7, capacitor C8, and linear regulator Q1;

the anode of the diode D1 is connected with the input end of the power supply 24V +, and the cathode of the diode D2 is connected with the anode of the diode D7, one end of the capacitor C7 and the pin 1 of the linear voltage stabilizer Q1; the anode of the diode D2 is connected with the anode of the diode D3, the other end of the capacitor C7, the 2-pin of the linear voltage stabilizer Q1 and one end of the capacitor C8 and then grounded; the cathode of the diode D3 is connected with the power supply 24-; the pin 3 of the output end of the linear voltage regulator Q1 is connected with the other end of the capacitor C8, the amplifying circuit, the filter circuit, the timing circuit and the counting circuit.

By adopting the technical scheme, the diode D1, the diode D2 and the diode D3 are used for ensuring the voltage flow direction; the capacitor C7 and the capacitor C8 are used for alternating current grounding and filtering alternating current components in the power supply; the power supply enters the linear regulator Q1 through pin 1 of the linear regulator Q1 for voltage reduction processing, and is output through pin 3 of the linear regulator Q1 to supply power for each circuit.

Optionally, the timing circuit includes: a timing module IC2, a resistor R2, a capacitor C4, and a capacitor C3;

a pin 1 of the timing module IC2 is connected with one end of a capacitor C4 and then grounded, a pin 2 is connected with a pin 13 of a module IC1 of the counting circuit 2, a pin 3 is connected with an RC oscillation circuit, a pin 4 is connected with one end of a resistor R2, a pin 8, a pin 16 of the counting module IC1, a pin 3 of a filter circuit and a linear voltage stabilizer Q1 of the power supply circuit 1, a pin 5 is connected with a capacitor C3, and a pin 6 and a pin 7 are connected with the other end of the capacitor C4, a capacitor input end TS and the other end of the resistor R2; the other end of the capacitor C3 is grounded.

By adopting the technical scheme, the resistor R1 and the capacitor C4 form a timing network; the 3 pins of the linear voltage regulator Q1 of the power supply circuit supply power to the timing module IC2 and start to operate through the 8 pins of the timing module IC 2; the counting circuit outputs a high-frequency signal which enters a timing module IC2 through a pin 2 of the timing module IC2 and receives a capacitance dynamic signal; when the capacitor dynamic signal starts to charge the capacitor C4 through the resistor R2, the pin 7 of the timing module IC2 is turned off, and the timing circuit outputs a low level signal; when the capacitor C4 is fully charged and lights up to a dynamic capacitance signal of 2/3, the capacitor C4 starts to discharge, and 7 of the timing module IC2 is already turned on, and the timing circuit outputs a high level signal, so that a cycle is performed, and finally, a carrier signal is output through the 3 pins of the timing module IC 2.

Optionally, the counting circuit comprises: a counting module IC1, a capacitor C2, a resistor R1, a capacitor C1, and a resonator Y;

the 8 pins of the counting module IC1 are connected with one end of a capacitor C1 and then grounded, the 10 pins are connected with the other end of a capacitor C1, one end of a resonator Y and one end of a resistor R1, the 11 pins are connected with the other end of the resonator Y, the other end of the resistor R1 and one end of a capacitor C2, the 12 pins are connected with the other end of a capacitor C2 and the other end of an RC oscillating circuit and then grounded, and the 16 pins are connected with the 3 pins of a linear voltage stabilizer Q1 of a timing circuit and a power supply circuit, an amplifying circuit and a filter circuit.

By adopting the technical scheme, the counting module IC1 is electrified and operates through a 16 pin, a forward voltage signal is output to the resonator Y through a 10 pin, and is input into the counting module IC1 through an 11 pin after oscillation processing of the resonator Y; after 9 times of frequency halving, a high-frequency signal is output to the timing circuit by a pin 13; meanwhile, the capacitor C1 and the capacitor C2 are used to assist the resonator Y in oscillation starting and stabilizing.

Optionally, the RC oscillating circuit includes: an oscillation module IC3C, a resistor R6, a sliding varistor W2, a resistor R4, a resistor R3, a capacitor C6, and a capacitor C5;

the 8 pins of the IC3C of the oscillation module are connected with one end of a resistor R6 and 9 pins, and the 10 pins are connected with one end of a resistor R4 and one end of a capacitor C6; the other end of the resistor R6 is connected with one end of a slide rheostat W2 and a filter circuit, the other end of the slide rheostat W2 is connected with the other end of a capacitor C2, the other end of the resistor R4 is connected with one end of a resistor R3 and one end of a capacitor C5, and the other end of the capacitor C6 is connected with the other end of a capacitor C1 of the counting circuit and then grounded.

By adopting the technical scheme, the timing circuit outputs a carrier signal, the carrier signal enters the oscillation module IC3C through a pin 10 of the oscillation module after being subjected to voltage division by the resistor R4 and the resistor R3, the internal circuit of the oscillation module IC3C is used for carrying out frequency modulation processing on a high-frequency signal output by the timing circuit, and a low-frequency signal is output.

Optionally, the filter circuit includes: a filter module IC3B, a resistor R5, a sliding rheostat W1;

a pin 6 of the filter module IC3B is connected to one end of the resistor R5 and one end of the slide rheostat W1, a pin 7 is connected to the other end of the slide rheostat W1 and the amplifying circuit, and a pin 5 is connected to the other end of the resistor R6 and one end of the slide rheostat W2; the other end of the resistor R5 is connected to pin 3 of the linear regulator Q1, pin 4 of the timing module IC2, and pin 16 of the counting module IC 1.

By adopting the technical scheme, the low-frequency signal output by the RC oscillation circuit enters through the 5 pins of the filtering module, and the clutter signals generated in the frequency modulation conversion processing are filtered through the internal circuit of the filtering module IC 3B.

Optionally, the amplifying circuit includes: an amplification module IC3A and a diode D4;

the 4 pins of the amplifying module IC3A are connected with the 3 pins of the linear voltage regulator Q1, the 3 pins are connected with the 7 pins of the filtering module IC3B, the 2 pins are connected with the cathode of the diode D4 and the 1 pin, and the anode of the diode D4 is connected with the 11 pins and then grounded.

By adopting the technical scheme, the filtered low-frequency signal is input into the amplifying module IC3A through the 3 pins, the amplitude of the pulse signal is amplified through the amplifying module IC3A, finally, the required voltage value is output through the 1 pin of the amplifying module IC3A, and the liquid level is detected in real time by observing the voltage value.

In summary, the present application includes at least one of the following beneficial technical effects:

the capacitance in the capacitor is changed along with the change of the contact area between the electrode plates, and a capacitor dynamic signal is released to the timing circuit; meanwhile, the timing circuit receives the high-frequency pulse signal output by the counting circuit, superposes the high-frequency carrier pulse signal and the capacitance dynamic signal, and finally outputs the high-frequency carrier pulse signal to the RC oscillating circuit; the RC oscillating circuit carries out frequency conversion on the high-frequency carrier signal to output a low-frequency signal, then the low-frequency signal is filtered through the filter circuit, clutter signals in the signal processing process of the timing circuit and the RC oscillating circuit are filtered, and the effect of the required pulse signal is finally output after the fixed-frequency signal with the clutter signals removed is amplified through the amplifying circuit.

Drawings

FIG. 1 is a flow chart of the fluid level apparatus process according to an embodiment of the present application;

FIG. 2 is a circuit diagram of a fluid level assembly according to an embodiment of the present application.

Description of the reference numerals: 1. a power supply circuit; 2. a counting circuit; 3. a timing circuit; 4. an RC oscillating circuit; 5. a filter circuit; 6. an amplifying circuit.

Detailed Description

The present application is described in further detail below with reference to figures 1-2.

The embodiment of the application discloses a liquid level measuring device. Referring to fig. 1, a liquid level measuring apparatus includes: the circuit comprises a capacitance module, a power supply circuit 1, a counting circuit 2, a timing circuit 3, an RC oscillating circuit 4, a filter circuit 5 and an amplifying circuit 6;

the capacitance module is used for providing a capacitance dynamic signal;

a power supply circuit 1 for supplying power;

the timing circuit 3 is connected with the capacitor module and used for converting the received capacitor dynamic signal into the frequency change of the pulse signal;

a counting circuit 2 connected with the timing circuit 3 for outputting high frequency signal to the timing circuit 3,

the timing circuit 3 superposes the pulse signal and the high-frequency signal to generate a carrier signal;

the RC oscillating circuit 4 is connected with the timing circuit 3 and is used for carrying out frequency conversion on the carrier signal to generate a low-frequency pulse signal;

the filter circuit 5 is connected with the RC oscillating circuit 4 and is used for filtering clutter in the low-frequency pulse signal output by the RC oscillating circuit 4;

and the amplifying circuit 6 is used for amplifying the low-frequency pulse signal with the clutter filtered.

A linear voltage stabilizer is arranged in the power supply circuit 1, and carries out synchronous rectification and voltage reduction processing on input voltage to provide required starting voltage for each circuit;

along with the continuous change of the liquid level of the insulating liquid, the contact area between the insulating liquid and the electrode plate in the capacitor module is also continuously changed, so that the capacitance in the capacitor is also changed along with the continuous change of the liquid level of the insulating liquid, and a dynamic signal of the capacitor is released;

the power supply circuit 1 supplies power to the timing circuit 3, the timing circuit 3 receives the dynamic capacitance signal and converts the dynamic capacitance signal into the frequency change of the pulse signal, the timing circuit 3 superposes the pulse signal and the high-frequency signal output by the counting circuit 2 to generate a carrier signal, the carrier signal is demodulated, filtered and amplified and transmitted to the single chip microcomputer, and the single chip microcomputer generates the liquid level height corresponding to the dynamic capacitance signal.

Referring to fig. 2, as an embodiment of the power supply circuit 1, the power supply circuit 1 includes: diode D1, diode D2, diode D3, capacitor C7, capacitor C8, and linear regulator Q1;

the anode of the diode D1 is connected with the input end of the power supply 24V +, and the cathode of the diode D2 is connected with the anode of the diode D7, one end of the capacitor C7 and the pin 1 of the linear voltage regulator Q1; the anode of the diode D2 is connected with the anode of the diode D3, the other end of the capacitor C7, the 2-pin of the linear voltage stabilizer Q1 and one end of the capacitor C8 and then grounded; the cathode of the diode D3 is connected with the power supply 24-; the pin of the output terminal 3 of the linear voltage regulator Q1 is connected to the other terminal of the capacitor C8, the amplifying circuit 6, the filter circuit 5, the timing circuit 3, and the counting circuit 2.

The diode D1, the diode D2, and the diode D3 are used to ensure a voltage flow direction; the capacitor C7 and the capacitor C8 are used for alternating current grounding and filtering alternating current components in the power supply;

the power supply outputs 24V voltage, enters a linear voltage regulator Q1 through a pin 1 of a linear voltage regulator Q1 for voltage reduction processing, outputs 15V power supply voltage and provides power for all circuits.

As an embodiment of the counter circuit 2, referring to fig. 2, the counter circuit 2 includes: a counting module IC1, a capacitor C2, a resistor R1, a capacitor C1, and a resonator Y;

the 8 pins of the counting module IC1 are connected to one end of a capacitor C1 and then grounded, the 10 pins are connected to the other end of a capacitor C1, one end of a resonator Y and one end of a resistor R1, the 11 pins are connected to the other end of the resonator Y, the other end of the resistor R1 and one end of a capacitor C2, the 12 pins are connected to the other end of a capacitor C2 and the RC oscillation circuit 4 and then grounded, and the 16 pins are connected to the 3 pins of the timing circuit 3 and the linear regulator Q1 of the power supply circuit 1, the amplifying circuit 6 and the filter circuit 5.

The counting module IC1 is powered on through a 16 pin and starts to operate, a forward voltage signal is output to the resonator Y through a 10 pin, and is input into the counting module IC1 through an 11 pin after oscillation processing of the resonator Y; after 9 times of frequency halving, a high-frequency signal is output to the timing circuit 3 by a pin 13; meanwhile, the capacitor C1 and the capacitor C2 are used to assist the oscillation starting and stabilizing of the resonator Y.

Referring to fig. 2, the timing circuit 3 includes, as an embodiment of the timing circuit 3: a timing module IC2, a resistor R2, a capacitor C4, and a capacitor C3;

a pin 1 of the timing module IC2 is connected with one end of a capacitor C4 and then grounded, a pin 2 is connected with a pin 13 of a module IC1 of the counting circuit 2, a pin 3 is connected with an RC oscillating circuit 4, a pin 4 is connected with one end of a resistor R2, a pin 8, a pin 16 of the counting module IC1, a pin 3 of a filter circuit 5 and a linear voltage stabilizer Q1 of the power supply circuit 1, a pin 5 is connected with a capacitor C3, and pins 6 and 7 are connected with the other end of the capacitor C4, a capacitor input terminal TS and the other end of the resistor R2; the other end of the capacitor C3 is grounded.

Resistor R1 and capacitor C4 form a timing network; the 3 pins of the linear voltage regulator Q1 of the power supply circuit 1 supply power to the timing module IC2 and start to operate through the 8 pins and 4 pins of the timing module IC 2; the counting circuit 2 outputs a high-frequency signal which enters the timing module IC2 through a pin 2 of the timing module IC2 and receives a capacitance dynamic signal at the same time; when the capacitor dynamic signal starts to charge the capacitor C4 through the resistor R2, the pin 7 of the timing module IC2 is turned off, and the timing circuit 3 outputs a low level signal; when the capacitor C4 is fully charged and reaches a dynamic capacitance signal of 2/3, the capacitor C4 starts to discharge, the timing module IC2 is already turned on, and the timing circuit 3 outputs a high level signal, so as to perform a cycle; and simultaneously, the high-frequency signal is superposed with the high-frequency signal of the 2-pin receiving counting circuit 2, and finally, a carrier pulse signal is output through a 3-pin of the timing module IC 2.

Referring to fig. 2, the RC oscillation circuit 4 is an embodiment of the RC oscillation circuit 4, and includes: an oscillation module IC3C, a resistor R6, a sliding varistor W2, a resistor R4, a resistor R3, a capacitor C6, and a capacitor C5;

the 8 pins of the IC3C of the oscillation module are connected with one end of a resistor R6 and 9 pins, and the 10 pins are connected with one end of a resistor R4 and one end of a capacitor C6; the other end of the resistor R6 is connected to one end of a sliding varistor W2 and the filter circuit 5, the other end of the sliding varistor W2 is connected to the other end of the capacitor C2, the other end of the resistor R4 is connected to one end of a resistor R3 and one end of a capacitor C5, and the other end of the capacitor C6 is connected to the other end of the capacitor C1 of the counter circuit 2 and then grounded.

A negative feedback pulse signal is input to a 9 pin of the oscillation module, a carrier pulse signal is output by the timing circuit 3 at the same time, the carrier pulse signal enters the oscillation module IC3C through a 10 pin of the oscillation module after being divided by a resistor R4 and a resistor R3, the low-frequency pulse signal output by the timing circuit 3 is subjected to frequency modulation processing through an internal circuit of the oscillation module IC3C, and the carrier signal subjected to low-frequency processing is output; the carrier signal is output to the filter circuit 5 through a pin of the oscillation module 8.

As an embodiment of the filter circuit 5, referring to fig. 2, the filter circuit 5 includes: a filter module IC3B, a resistor R5, a sliding rheostat W1;

a pin 6 of the filter module IC3B is connected to one end of the resistor R5 and one end of the slide rheostat W1, a pin 7 is connected to the other end of the slide rheostat W1 and the amplifying circuit 6, and a pin 5 is connected to the other end of the resistor R6 and one end of the slide rheostat W2; the other end of the resistor R5 is connected to pin 3 of the linear regulator Q1, pin 4 of the timing module IC2, and pin 16 of the counting module IC 1.

The output signal of the 7 pins of the filter module IC3B enters the negative feedback end of the filter module IC3B through the 6 pins of the filter module IC3B after being adjusted by the slide rheostat W1; meanwhile, a low-frequency pulse signal output by the RC oscillating circuit 4 enters through a pin 5 of the filtering module, and clutter signals generated in the frequency modulation conversion processing are filtered through an internal circuit of the filtering module IC 3B.

Referring to fig. 2, as an embodiment of the amplifier circuit 6, the amplifier circuit 6 includes: an amplification module IC3A and a diode D4;

the 4 pins of the amplifying module IC3A are connected with the 3 pins of the linear voltage regulator Q1, the 3 pins are connected with the 7 pins of the filtering module IC3B, the 2 pins are connected with the cathode of the diode D4 and the 1 pin, and the anode of the diode D4 is connected with the 11 pins and then grounded.

The filtered low-frequency pulse signal is input into an amplifying module IC3A through a pin 3, the amplitude of the pulse signal is amplified through an amplifying module IC3A, finally, a required voltage value is output through a pin 1 of the amplifying module IC3A, and the liquid level is detected in real time by observing the voltage value.

The above embodiments are preferred embodiments of the present application, and the protection scope of the present application is not limited by the above embodiments, so: all equivalent changes made according to the structure, shape and principle of the present application shall be covered by the protection scope of the present application.

Claims (7)

1. A device for measuring fluid level, comprising: the circuit comprises a capacitance module, a counting circuit (2), a timing circuit (3), an RC oscillating circuit (4), a filter circuit (5) and an amplifying circuit (6);

the capacitance module is used for providing a capacitance dynamic signal;

the timing circuit (3) is connected with the capacitor module and used for converting the received capacitor dynamic signal into a pulse signal frequency change;

the counting circuit (2) is connected with the timing circuit (3) and is used for outputting a high-frequency pulse signal to the timing circuit (3);

the RC oscillating circuit (4) is connected with the timing circuit (3) and is used for carrying out frequency conversion on the carrier signal to generate a low-frequency pulse signal;

the filter circuit (5) is connected with the RC oscillating circuit (4) and is used for filtering clutter in the low-frequency pulse signal output by the RC oscillating circuit (4);

and the amplifying circuit (6) is used for amplifying the low-frequency pulse signal of which the clutter is filtered.

2. A device for measuring a liquid level according to claim 1, characterized in that it further comprises a power supply circuit (1), the power supply circuit (1) comprising: diode D1, diode D2, diode D3, capacitor C7, capacitor C8, and linear regulator Q1;

the anode of the diode D1 is connected with the input end of the power supply 24V +, and the cathode of the diode D2 is connected with the anode of the diode D7, one end of the capacitor C7 and the pin 1 of the linear voltage stabilizer Q1; the anode of the diode D2 is connected with the anode of the diode D3, the other end of the capacitor C7, the 2-pin of the linear voltage stabilizer Q1 and one end of the capacitor C8 and then grounded; the cathode of the diode D3 is connected with the power supply 24-; the output end 3 pin of the linear voltage stabilizer Q1 is connected with the other end of the capacitor C8, the amplifying circuit (6), the filter circuit (5), the timing circuit (3) and the counting circuit (2).

3. A device for measuring a fluid level according to claim 1, wherein said timing circuit (3) comprises: a timing module IC2, a resistor R2, a capacitor C4, and a capacitor C3;

a pin 1 of the timing module IC2 is connected with one end of a capacitor C4 and then grounded, a pin 2 is connected with a pin 13 of a module IC1 of the counting circuit (2), a pin 3 is connected with an RC oscillation circuit (4), a pin 4 is connected with one end of a resistor R2, a pin 8, a pin 16 of the counting module IC1, a pin 3 of a filter circuit (5) and a linear voltage stabilizer Q1 of the power supply circuit (1), a pin 5 is connected with a capacitor C3, and a pin 6 and a pin 7 are connected with the other end of the capacitor C4, a capacitor input end TS and the other end of the resistor R2; the other end of the capacitor C3 is grounded.

4. A device for measuring a fluid level according to claim 1, wherein said counting circuit (2) comprises: a counting module IC1, a capacitor C2, a resistor R1, a capacitor C1, and a resonator Y;

an 8 pin of a counting module IC1 is connected with one end of a capacitor C1 and then grounded, a 10 pin is connected with the other end of a capacitor C1, one end of a resonator Y and one end of a resistor R1, an 11 pin is connected with the other end of the resonator Y, the other end of the resistor R1 and one end of a capacitor C2, a 12 pin is connected with the other end of a capacitor C2 and the other end of an RC oscillating circuit (4) and then grounded, and a 16 pin is connected with a timing circuit (3), a 3 pin of a linear voltage stabilizer Q1 of a power supply circuit (1), an amplifying circuit (6) and a filter circuit (5).

5. A device for measuring a liquid level according to claim 1, wherein said RC oscillating circuit (4) comprises: an oscillation module IC3C, a resistor R6, a sliding varistor W2, a resistor R4, a resistor R3, a capacitor C6, and a capacitor C5;

an oscillation module IC3C has 8 pins connected to one end of a resistor R6 and 9 pins, and 10 pins connected to one end of a resistor R4 and one end of a capacitor C6; the other end of the resistor R6 is connected with one end of a slide rheostat W2 and the filter circuit (5), the other end of the slide rheostat W2 is connected with the other end of a capacitor C2, the other end of the resistor R4 is connected with one end of a resistor R3 and one end of a capacitor C5, and the other end of the capacitor C6 is connected with the other end of the capacitor C1 of the counting circuit (2) and then grounded.

6. A device for measuring a liquid level according to claim 4, characterized in that said filtering circuit (5) comprises: a filter module IC3B, a resistor R5, a sliding rheostat W1;

a pin 6 of the filter module IC3B is connected with one end of a resistor R5 and one end of a slide rheostat W1, a pin 7 is connected with the other end of the slide rheostat W1 and the amplifying circuit (6), and a pin 5 is connected with the other end of the resistor R6 and one end of a slide rheostat W2; the other end of the resistor R5 is connected to pin 3 of the linear regulator Q1, pin 4 of the timing module IC2, and pin 16 of the counting module IC 1.

7. A device for measuring a liquid level according to claim 1, wherein said amplification circuit (6) comprises: an amplification module IC3A and a diode D4;

the 4 pins of the amplifying module IC3A are connected with the 3 pins of the linear voltage regulator Q1, the 3 pins are connected with the 7 pins of the filtering module IC3B, the 2 pins are connected with the cathode of the diode D4 and the 1 pin, and the anode of the diode D4 is connected with the 11 pins and then grounded.

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