A lightning and surge-proof turbine flow detection signal processing circuit and mainboard

Abstract

The present invention relates to the technical field of turbine flow detection, and in particular to a turbine flow detection signal processing circuit and a mainboard for lightning and surge protection. The turbine flow detection signal processing circuit of the present invention comprises: an amplifying and shaping circuit, a power supply protection unit, an input protection unit, and an output protection unit. The present invention is provided with a power supply protection unit. On the one hand, the first-level protection is formed by GDTN tubes D1 and D2, and the strong surge pulse can be initially released to reduce the protection processing pressure of the subsequent circuit; on the other hand, the second-level protection is formed by the ingenious combination of D3, D4, C4, C7, L1, L2, L3, and L4, so that the circuit protection performance is greatly improved; and D5 is also used to prevent damage caused by wrong power connection. In addition, further protection is provided at the input end and the output end respectively. The present invention solves the problem that the existing signal processing device for turbine flow detection lacks lightning protection and surge protection functions.

Description

Technical Field

[0001] The present invention relates to the technical field of turbine flow detection, in particular to a turbine flow detection signal processing circuit and a mainboard capable of preventing lightning strikes and surges. Background Art

[0002] A turbine flowmeter is a commonly used instrument for measuring liquid flow. The turbine flowmeter's rotational speed is detected by a sensor coil mounted outside the casing. The sensor coil generates a turbine detection signal, which is processed into a square wave signal, which is then converted into the measured liquid flow rate.

[0003] Conventional signal processing devices currently available on the market for turbine flow detection (such as signal processing motherboards) have two shortcomings: 1. They lack lightning and surge protection functions. When encountering lightning strikes or surges, high-intensity voltage and current will flow into the signal processing circuit, which can easily exceed the maximum tolerance of electronic components and cause component burnout; 2. They can only output square wave signals of a single polarity. However, the instruments used on site for subsequent processing of square wave signals are not fixed, and different instruments have different requirements for the input square wave polarity. This may cause the square wave signal to not match the instrument. Summary of the Invention

[0004] Based on this, it is necessary to provide a turbine flow detection signal processing circuit, mainboard, and processing module that are lightning-proof and surge-proof in order to address the problem that the existing signal processing device for turbine flow detection lacks lightning protection and surge protection functions.

[0005] The present invention is achieved by adopting the following technical solutions:

[0006] In a first aspect, the present invention discloses a turbine flow detection signal processing circuit for protection against lightning strikes and surges, comprising: an amplifying and shaping circuit, a power supply protection unit, an input protection unit, and an output protection unit.

[0007] The amplifying and shaping circuit is used to process the turbine flow detection signal into two square wave signals with opposite polarity. The turbine flow detection signal is input from the signal input terminals IN1 and IN2 of the amplifying and shaping circuit, and the two square wave signals with opposite polarity are output from the signal output terminals FO- and FO of the amplifying and shaping circuit respectively.

[0008] The power supply protection unit is connected to the power supply terminals V+ and V- of the amplifying and shaping circuit to release strong surge pulses. The power supply protection unit includes: GDTN tube D1, TVS tube D4, TVS tube D3, diode D5, capacitor C4, capacitor C7, magnetic beads L1, magnetic beads L2, magnetic beads L3, magnetic beads L4, capacitor C5, GDTN tube D2; the first end of D1 is connected to V+ and the second end is connected to V-; the positive pole of D5 is connected to the first end of D1; the positive pole of D4 is connected to the second end of D1 and the negative pole is connected to the negative pole of D5; the first end of L3 is connected to the negative pole of D4; the first end of L4 is connected to the positive pole of D4; The first end of C7 is connected to the second end of L3, and the second end is connected to the second end of L4; the positive end of D3 is connected to the second end of C7, and the negative end is connected to the first end of C7; the first end of L1 is connected to the negative end of D3, and the second end is connected to the constant voltage power supply VCC; the first end of L2 is connected to the positive end of D3, and the second end is connected to GND; the first end of C4 is connected to the second end of L1, and the second end is connected to the second end of L2; the first end of D2 is connected to V-; the first end of C5 is connected to the first end of D2, and the second end is connected to the second end of D2.

[0009] The input protection unit is connected to IN1 and IN2 and is used to protect IN1 and IN2.

[0010] The output protection part is connected to FO- and FO and is used to protect FO- and FO.

[0011] The turbine flow detection signal processing circuit for protection against lightning strikes and surges implements the method or process according to the embodiment of the present disclosure.

[0012] In a second aspect, the present invention discloses a mainboard on which the lightning and surge-proof turbine flow detection signal processing circuit disclosed in the first aspect is printed.

[0013] Such a mainboard implements the method or process according to the embodiments of the present disclosure.

[0014] The turbine flow detection signal processing module implements the method or process according to the embodiment of the present disclosure.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] 1. This invention incorporates a power supply protection unit. First, GDTN transistors D1 and D2 form the first level of protection, initially discharging strong surge pulses to alleviate the pressure on subsequent circuit protection. Second, the ingenious combination of D3, D4, C4, C7, L1, L2, L3, and L4 forms the second level of protection, significantly improving circuit protection performance. Furthermore, D5 prevents damage caused by incorrect power connection. Furthermore, further protection is provided at both the input and output terminals.

[0017] 2. The present invention designs an amplification and shaping circuit, which first amplifies the turbine flow detection signal through the signal amplification part to obtain an amplified signal, then introduces the reference voltage signal through the reference voltage part, and then compares the amplified signal with the reference voltage signal through the signal output part to obtain square wave signal 1; finally, two branches are set in the signal output part, one of which directly outputs square wave signal 1, and the other branch inverts square wave signal 1 and outputs square wave signal 2, so that the polarities of square wave signal 1 and square wave signal 2 always remain opposite, thereby obtaining two square wave signals with opposite polarities, which can adapt to different instrument input signal requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a structural diagram of a turbine flow detection signal processing circuit for lightning and surge protection in Example 1 of the present invention;

[0019] Figure 2 for Figure 1 A magnified view of the middle signal amplifier section;

[0020] Figure 3 for Figure 1 Enlarged view of the middle reference voltage section;

[0021] Figure 4 for Figure 1 A magnified view of the middle signal comparison section;

[0022] Figure 5 for Figure 1 Enlarged view of the signal output part and output protection part;

[0023] Figure 6 for Figure 1 Enlarged view of the power supply protection unit;

[0024] Figure 7 for Figure 1 Enlarged view of the middle input protection part;

[0025] Figure 8 This is a performance verification comparison chart of the motherboard in Example 2 of the present invention. DETAILED DESCRIPTION

[0026] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0027] It should be noted that when a component is referred to as being "mounted on" another component, it may be directly on the other component or there may be a central component. When a component is considered to be "set on" another component, it may be directly set on the other component or there may be a central component. When a component is considered to be "fixed to" another component, it may be directly fixed to the other component or there may be a central component.

[0028] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this invention pertains. The terms used herein in the specification of the present invention are for the purpose of describing specific embodiments only and are not intended to limit the present invention. The term "or / and" as used herein includes any and all combinations of one or more of the associated listed items.

[0029] Example 1

[0030] See Figure 1 , Figure 1 This is a circuit diagram of the turbine flow detection signal processing circuit for lightning and surge protection in the present invention.

[0031] From the component point of view, this turbine flow detection signal processing circuit includes: 9 capacitors, recorded as C1~C9; 9 resistors, recorded as R1~R9; 4 operational amplifiers, recorded as U1.1~U1.4; 2 GDTN tubes, recorded as D1~D2; 6 TVS tubes, recorded as D3, D4, D6~D9; 1 diode, recorded as D5; 4 magnetic beads, recorded as L1~L4.

[0032] Functionally, the turbine flow detection signal processing circuit can be divided into: an amplifying and shaping circuit, a power supply protection unit, an input protection unit, and an output protection unit.

[0033] The following describes each part one by one:

[0034] 1. The amplifying and shaping circuit is used to process the turbine flow detection signal into two square wave signals with opposite polarity. The turbine flow detection signal is input from the signal input terminals IN1 and IN2 of the amplifying and shaping circuit, and the two square wave signals with opposite polarity are output from the signal output terminals FO- and FO of the amplifying and shaping circuit respectively.

[0035] The amplifier and shaping circuit can be divided into the following parts according to their functions: signal amplification part, reference voltage part, signal comparison part, and signal output part.

[0036] 1.1, the signal amplifier is used to amplify the turbine flow detection signal to obtain an amplified signal. Figure 2Specifically, the signal amplification unit includes: C3, R6, R7, and U1.1. The first end of C3 is connected to IN1, and the second end is connected to IN2. The first end of R6 is connected to the first end of capacitor C3. The first end of R7 is connected to the second end of R6. The operational amplifier U1.1 has its inverting input connected to the second end of R6, its non-inverting input connected to IN2, its output connected to the second end of R7, its power input connected to the constant voltage input VCC, and its ground terminal connected to GND.

[0037] C3 is used to filter out unwanted high-frequency interference and clutter. U1.1, R6, and R7 form a negative feedback amplifier—the gain A = R7 / R6. This amplifier generates the IN*A output from U1.1. It should be noted that the IN*A output is a sinusoidal signal.

[0038] In this embodiment 1, the specifications of C3 are 10nF, R6 are 20K, R7 are 510K, and U1.1 is an LM2902DR. Of course, other components can also be used, but their specifications must match the functions of this part.

[0039] 1.2, the reference voltage section is used to provide a reference voltage signal. Figure 3 Specifically, the reference voltage unit includes R8, U1.4, R9, and C2. The first end of R8 is connected to VCC. U1.4's inverting input is connected to IN2, its non-inverting input is connected to the second end of R8, and its output is connected to IN2. The first end of R9 is connected to the second end of R8, and its second end is connected to GND. The first end of C2 is connected to the second end of R8, and its second end is connected to GND.

[0040] Among them, R8 and R9 divide the voltage of VCC to obtain the reference voltage V2; V2 = R9*VCC / (R8+R9).

[0041] C2 eliminates noise and improves stability; U1.4 acts as a follower to increase driving capability. The output of U1.4 outputs a reference voltage, IN2 = V2.

[0042] In this embodiment 1, the specifications of R8 and R9 are both 5.1K; the specifications of U1.4 are LM2902DR, and the specifications of C2 are 1uF. Of course, other components can also be used, but their specifications must match the functions of this part.

[0043] 1.3, the signal comparison unit is used to compare the amplified signal with the reference voltage signal and obtain a square wave signal. Figure 4Specifically, the signal comparison unit includes: R5, U1.2, R4, C1, and R1. The first end of R5 is connected to the output of U1.1. The inverting input of U1.2 is connected to IN2, and the non-inverting input is connected to the first end of R5. The first end of R4 is connected to the second end of R5. The first end of C1 is connected to the output of U1.2, and the second end is connected to the second end of R4. The first end of R1 is connected to the second end of C1, and the second end is connected to GND.

[0044] U1.2, C1, R4, and R5 form a positive feedback shaping amplifier circuit, which converts the IN*A output from U1.1 into a standard square wave signal F, which is output from U1.2. Furthermore, C1 and R1 form a positioning function, ensuring that F is low when there is no input signal.

[0045] In this embodiment 1, R5 is 20K; R4 and R1 are both 1M; U1.2 is LM2902DR; and C1 is 10uF. Of course, other components can also be used, but their specifications must match the functions of this part.

[0046] 1.4. The signal output unit includes branch 1 and branch 2. Branch 1 is used to output square wave signal 1; branch 2 is used to invert square wave signal 1 and output square wave signal 2; the polarities of square wave signal 1 and square wave signal 2 always remain opposite.

[0047] Since the output protection part is connected to FO- and FO and is used to protect FO- and FO, it is described together with the signal output part.

[0048] See Figure 5 Branch 1 comprises R2, C9, and D6. The first end of resistor R2 is connected to the output of U1.2, and the second end is connected to FO. C9's first end is connected to the second end of R2, and the second end is connected to GND. D6's positive terminal is connected to V-, and its negative terminal is connected to FO. Branch 2 comprises U1.3, R3, C8, and D7. U1.3's inverting input is connected to IN2, and its non-inverting input is connected to the output of U1.2. R3's first end is connected to the output of U1.3, and its second end is connected to FO-. C8's first end is connected to the second end of R3, and its second end is connected to GND. D7's positive terminal is connected to V-, and its negative terminal is connected to FO-.

[0049] Among them, U1.3 acts as an inverter, inverting the standard square wave signal F from U1.2 and outputting it.

[0050] D6, D7, R2, R3, C8, and C9 form the output protection circuit. D6 and D7 protect the external circuit from unexpected surge voltages exceeding 26V, which could cause damage. R2 and R3 are output protection resistors, preventing damage to the internal circuitry in the event of an unexpected output short circuit. C8 and C9 eliminate high-frequency noise.

[0051] In this embodiment 1, D6 and D7 are both SMAJ26A. R2 and R3 are both 2K. U1.3 is an LM2902DR. C8 and C9 are both 47nF. Of course, other components can be used, but they must match the function of this part.

[0052] 2. The power supply protection unit is connected to the power supply terminals V+ and V- of the amplifier and shaping circuit to release strong surge pulses. The power supply protection unit is the core of the turbine flow detection signal processing circuit to protect against lightning and surges.

[0053] See Figure 6 Specifically, the power supply protection unit includes: GDTN tube D1, TVS tube D4, TVS tube D3, diode D5, capacitor C4, capacitor C7, magnetic bead L1, magnetic bead L2, magnetic bead L3, magnetic bead L4, capacitor C5, and GDTN tube D2. The first end of D1 is connected to V+, and the second end is connected to V-; the positive end of D5 is connected to the first end of D1; the positive end of D4 is connected to the second end of D1, and the negative end is connected to the negative end of D5; the first end of L3 is connected to the negative end of D4; the first end of L4 is connected to the positive end of D4; the first end of C7 is connected to the second end of L3, and the second end is connected to the second end of L4; the positive end of D3 is connected to the second end of C7, and the negative end is connected to the first end of C7; the first end of L1 is connected to the negative end of D3, and the second end is connected to the constant voltage power supply VCC; the first end of L2 is connected to the positive end of D3, and the second end is connected to GND; the first end of C4 is connected to the second end of L1, and the second end is connected to the second end of L2; the first end of D2 is connected to V-; the first end of C5 is connected to the first end of D2, and the second end is connected to the second end of D2.

[0054] Among them, D1 and D2 constitute the first level of protection; D3, D4, C4, C7, L1, L2, L3, and L4 constitute the second level of protection; and D5 constitutes additional protection.

[0055] D1 and D2 have high discharge currents (up to 2kA) and fast reaction speeds (down to microseconds), but their turn-on discharge voltages are relatively high (approximately 50-70V). Therefore, D1 and D2 are placed at the power supply end for primary protection. D3, D4, D6, D7, D8, and D9 have selectable turn-on discharge voltages, but their discharge currents are only around 30A. Therefore, they are placed after D1 and at the input and output signal terminals. L1, L2, L3, and L4 have inductive properties and, together with C4 and C7, form a π-type filter, effectively suppressing transient high-voltage and high-frequency noise. D3, D4, D5, and D6 will short-circuit and discharge when the operating voltage exceeds the normal value and reaches above the threshold, protecting circuit components from burnout. D5 prevents instrument damage caused by wiring errors.

[0056] In addition, the second end of D2 can also be used as the shell terminal KE, which is convenient for leaving a shell pin in the subsequent board making to conduct strong surge pulses through the motherboard shell.

[0057] In this embodiment 1, the specifications of D1 and D2 are both GDTN2RS3-75; the specification of D5 is M7; the specifications of D3 and D4 are both SMAJ26A; the specifications of C4 and C7 are both 100nF / 50V; and the specifications of L1 to L4 are all 2.2K. Of course, other specifications of components can also be used, but they must match the functions of this part.

[0058] 3. The input protection part is connected to IN1 and IN2 to protect IN1 and IN2. Figure 7 Specifically, the input protection unit includes: D8 and D9. The positive pole of D8 is connected to GND and the negative pole is connected to IN2; the positive pole of D9 is connected to GND and the negative pole is connected to IN1.

[0059] D8 and D9 are connected to IN1 and IN2. When the signal voltage at this end exceeds the threshold, it will be broken down and short-circuited to discharge, thus protecting the signal input end.

[0060] In this embodiment 1, the specifications of D8 and D9 are both SMAJ15A. Of course, components of other specifications can also be used, but their specifications need to match the functions of this part.

[0061] In general, based on the above-mentioned turbine flow detection signal processing circuit, the input turbine detection signal can be converted into two square wave signals with opposite polarities, and protection against lightning strikes and surges can be achieved.

[0062] Example 2

[0063] This embodiment 2 discloses a mainboard on which the lightning and surge protection turbine flow detection signal processing circuit disclosed in embodiment 1 is printed.

[0064] Generally speaking, the pins of this type of motherboard include: signal input pin 1, signal input pin 2, power supply pin 1, power supply pin 2, ground pin, signal output pin 1, and signal output pin 2.

[0065] Signal input pin 1 is connected to IN1. Signal input pin 2 is connected to IN2. Power supply pin 1 is connected to V+. Power supply pin 2 is connected to V-. Ground pin is connected to GND. Signal output pin 1 is connected to FO-. Signal output pin 2 is connected to FO.

[0066] This motherboard can also be equipped with a housing for protection. Furthermore, as mentioned above, if the second end of D2 is used as the housing terminal KE, then the motherboard's pins should also include a housing connection pin for connecting to KE. This allows the housing to be connected via the housing connection pin, thereby directing strong surge pulses through the motherboard's housing.

[0067] In order to verify the effectiveness of the turbine flow detection signal processing circuit for lightning and surge protection in Example 1, this Example 2 further conducts a performance test comparison on the above-mentioned mainboard. The specific operations are as follows:

[0068] 1. Install the turbine (DN25L model) on the standard turbine flow calibration bench; start the calibration bench to remove air from the pipe and ensure that the pipe is full to make the measurement more accurate, and adjust the turbine flow to the required size.

[0069] 2. Install the turbine coil onto the turbine, and connect the signal output end of the turbine coil to the signal input pin 1 and signal input pin 2 of the mainboard; connect the power supply pin 1 and power supply pin 2 of the mainboard to the power supply; connect the mainboard's shell connection pin to the shell; connect the mainboard's signal output pin 1 or signal output pin 2 to the secondary instrument and oscilloscope; the secondary instrument is used to convert the frequency of the square wave signal into flow, thereby facilitating the observation of the cumulative flow; the oscilloscope is used to assist in observing the waveform of the output square wave signal.

[0070] 3. Open the valve of the standard turbine flow calibration bench and close the valve after running for a certain period of time; observe the cumulative flow of the standard turbine flow calibration bench and the secondary instrument, and compare and calculate the accuracy and repeatability.

[0071] 4. Test the motherboard multiple times in a normal environment, a lightning strike environment, and a surge environment. The lightning strike and surge environments are provided by a lightning simulation box and surge test equipment.

[0072] 5. Compare the accuracy and repeatability of multiple tests under the two test environments. See the results. Figure 8 :

[0073] As can be seen, the motherboard's measurement accuracy remained high in both test environments. Furthermore, after being struck by lightning and subjected to surges, the motherboard maintained this high level of accuracy, demonstrating its lightning and surge protection.

[0074] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0075] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent for this invention shall be determined by the appended claims.

Claims

1. A turbine flow detection signal processing circuit for lightning and surge protection, characterized in that: include: An amplifying and shaping circuit, which is used to process the turbine flow detection signal into two square wave signals with opposite polarities; wherein the turbine flow detection signal is input from the signal input terminals IN1 and IN2 of the amplifying and shaping circuit, and the two square wave signals with opposite polarities are output from the signal output terminals FO- and FO of the amplifying and shaping circuit respectively; A power supply protection unit is connected to the power supply terminals V+ and V- of the amplifying and shaping circuit and is used to release strong surge pulses; the power supply protection unit includes: a GDTN tube D1, a TVS tube D4, a TVS tube D3, a diode D5, a capacitor C4, a capacitor C7, a magnetic bead L1, a magnetic bead L2, a magnetic bead L3, a magnetic bead L4, a capacitor C5, and a GDTN tube D2; the first end of D1 is connected to V+ and the second end is connected to V-; the positive electrode of D5 is connected to the first end of D1; the positive electrode of D4 is connected to the second end of D1 and the negative electrode is connected to the negative electrode of D5; the first end of L3 is connected to D4 The negative electrode of L4 is connected to the positive electrode of D4; the first end of C7 is connected to the second end of L3, and the second end is connected to the second end of L4; the positive electrode of D3 is connected to the second end of C7, and the negative electrode is connected to the first end of C7; the first end of L1 is connected to the negative electrode of D3, and the second end is connected to the constant voltage power supply VCC; the first end of L2 is connected to the positive electrode of D3, and the second end is connected to GND; the first end of C4 is connected to the second end of L1, and the second end is connected to the second end of L2; the first end of D2 is connected to V-; the first end of C5 is connected to the first end of D2, and the second end is connected to the second end of D2; The amplifying and shaping circuit comprises: A signal amplifier, which is used to amplify the turbine flow detection signal to obtain an amplified signal; A reference voltage unit, which is used to provide a reference voltage signal; A signal comparison unit, used for comparing the amplified signal with the reference voltage signal and obtaining a square wave signal 1; The signal output part includes a branch 1 and a branch 2; wherein the branch 1 is used to output a square wave signal 1; the branch 2 is used to invert the square wave signal 1 and then output a square wave signal 2; the polarities of the square wave signal 1 and the square wave signal 2 are always kept opposite; The signal amplification unit comprises: A capacitor C3, a first end of which is connected to IN1 and a second end of which is connected to IN2; a resistor R6, a first end of which is connected to a first end of the capacitor C3; a resistor R7, a first end of which is connected to the second end of R6; Operational amplifier U1.1, with its inverting input terminal connected to the second terminal of R6, its non-inverting input terminal connected to IN2, its output terminal connected to the second terminal of R7, its power input terminal connected to the constant voltage input terminal VCC, and its ground terminal connected to GND; The reference voltage unit comprises: A resistor R8, a first end of which is connected to VCC; Operational amplifier U1.4, with its inverting input connected to IN2, its non-inverting input connected to the second end of R8, and its output connected to IN2; A resistor R9, a first end of which is connected to the second end of R8 and a second end of which is connected to GND; A capacitor C2, a first end of which is connected to the second end of R8 and a second end of which is connected to GND; The signal comparison unit comprises: A resistor R5, a first end of which is connected to the output end of U1.1; Operational amplifier U1.2, with its inverting input terminal connected to IN2 and its non-inverting input terminal connected to the first end of R5; a resistor R4, a first end of which is connected to the second end of R5; Capacitor C1, a first end of which is connected to the output end of U1.2, and a second end of which is connected to the second end of R4; A resistor R1, a first end of which is connected to the second end of C1 and a second end of which is connected to GND; The branch 1 is provided with a resistor R2, a capacitor C9, and a TVS tube D6; the first end of R2 is connected to the output end of U1.2, and the second end is connected to FO; the first end of C9 is connected to the second end of R2, and the second end is connected to GND; the positive electrode of D6 is connected to V-, and the negative electrode is connected to FO; The branch 2 is provided with an operational amplifier U1.3, a resistor R3, a capacitor C8, and a TVS tube D7; the inverting input terminal of U1.3 is connected to IN2, and the non-inverting input terminal is connected to the output terminal of U1.2; the first end of R3 is connected to the output terminal of U1.3, and the second end is connected to FO-; the first end of C8 is connected to the second end of R3, and the second end is connected to GND; the positive electrode of D7 is connected to V-, and the negative electrode is connected to FO-; an input protection part, which is connected to IN1 and IN2, and is used to protect IN1 and IN2; the input protection part includes: a TVS tube D8, whose positive electrode is connected to GND and the negative electrode is connected to IN2; TVS tube D9, with its positive electrode connected to GND and its negative electrode connected to IN1; as well as An output protection part is connected to FO- and FO to protect FO- and FO; wherein D6, D7, R2, R3, C8, and C9 constitute the output protection part; The second end of D2 also serves as the outer shell terminal KE.

2. A motherboard, characterized in that: The mainboard is printed with the turbine flow detection signal processing circuit for lightning and surge protection as claimed in claim 1; The pins of the mainboard include: Signal input pin 1, used to connect IN1; Signal input pin 2, used to connect IN2; Power supply pin 1, used to connect V+; Power supply pin 2, used to connect V-; Ground pin, used to connect GND; Signal output pin 1, used to connect FO-; Signal output pin 2, used to connect FO.

3. The mainboard according to claim 2, characterized in that: The mainboard is provided with a housing; The pins of the mainboard also include shell connecting pins for connecting to the KE.

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