Novel rotating speed display instrument

Abstract

A novel rotating speed display instrument belongs to the technical field of tachometers and comprises a single-chip microcomputer module, a power supply module, an output circuit, a signal amplification circuit and a selection circuit, and the single-chip microcomputer module, the power supply module, the output circuit, the signal amplification circuit and the selection circuit are installed in a shell and electrically connected. The signal output end of the sensor is electrically connected with the two signal wiring piles through signal lines. According to the utility model, the application is more flexible, external interference signals are effectively and electrically isolated through an optical coupler and the like, direct-current component signals are filtered out, small filtered signals are amplified, signals output by an operational amplifier are input into the phase inverter, the amplitude of the signals is judged and distinguished again by utilizing the Schmidt trigger circuit characteristics of the phase inverter, and finally, the amplitude of the signals is judged and distinguished. After the high-speed optocoupler is subjected to optoelectronic isolation, clean and stable bus digital signals are output to the single-chip microcomputer module for rotating speed display, and due to the fact that interference of external signals on rotating speed detection is reduced, displayed rotating speed data are more real and reliable.

Description

Technical Field

[0001] This utility model relates to the field of instrumentation technology, and in particular to a novel speed display instrument. Background Technology

[0002] A speed display instrument is a device that combines a speed sensor with its signal input terminal and the signal output terminal of the speed sensor. During operation, it converts the speed signal of the equipment output by the speed sensor into a dynamically changing signal, which is then displayed on a multi-digit LED digital tube or LCD screen. By observing the corresponding numbers, relevant personnel can understand the speed data of the equipment in real time.

[0003] The speed sensors used in speed display instruments for turbine shafts, etc., are generally magnetoresistive sensors or Hall sensors. These are passive devices. The matching speed-measuring metal gear 6 is installed on the rear outer end of the turbine shaft 7, etc., while the magnetoresistive sensor or Hall sensor 8 is installed on the side of the turbine casing. The detection surface of the magnetoresistive sensor or Hall sensor 8 is spaced a certain distance from the speed-measuring metal gear 6. When the turbine shaft 7 drives the speed-measuring metal gear 6 to rotate, the magnetic poles inside the magnetoresistive sensor or Hall sensor 8 continuously change. The magnetoresistive sensor or Hall sensor 8 detects the changing magnetic poles and outputs a dynamic AC small analog signal that changes with the speed. The speed display instrument processes this AC small signal, converting it into a signal through relevant circuitry, and displays it on a multi-digit LED display or LCD. While existing speed display instruments for turbine shafts, which provide digital displays, meet the needs of shaft speed detection to some extent, their internal circuitry directly processes analog speed signals for display. In practical applications, analog signals are susceptible to interference during transmission (such as interference from the motor's magnetic field), leading to signal distortion or loss and affecting signal fidelity. When the turbine shaft speed is below 100 revolutions per minute, there is a chance of data deviation (the lower the turbine shaft speed, the smaller the analog electrical signal output by the magnetoresistive or Hall sensor, and the greater the chance of interference). This negatively impacts the display and acquisition of normal speed data, making it impossible to guarantee the accuracy and validity of the low-speed turbine shaft data. Furthermore, existing speed display instruments based on magnetoresistive or Hall sensors generally only process and display signals from one type of sensor, resulting in a relatively limited application. Utility Model Content

[0004] To overcome the limitations of existing speed display instruments used in turbine shafts and other applications, which suffer from the drawbacks described in the background, this invention provides a novel speed display instrument based on existing mature single-chip microcomputer modules with digital display tube functionality. Through the combined action of related circuits, it can electrically isolate signals input from magnetoresistive sensors or Hall effect sensors, converting the amplitude of suitable signals into corresponding high and low level signals, which are then input to the input terminal of a high-speed optocoupler. After opto-isolation, the high-speed optocoupler outputs a clean and stable signal for digital display by the single-chip microcomputer module. This reduces interference from external signals on speed detection, resulting in more accurate and reliable speed data and greater application flexibility.

[0005] The technical solution adopted by this utility model to solve its technical problem is:

[0006] A novel speed display instrument includes a microcontroller module, a power supply module, and also has an output circuit, a signal amplification circuit, and a selection circuit. The microcontroller module, power supply module, output circuit, signal amplification circuit, and selection circuit are installed inside a housing. The signal input terminal of the signal amplification circuit is electrically connected to two signal terminals, with the interface of the signal terminals located outside the rear of the housing. The power output terminal of the power supply module is electrically connected to the power input terminals of the microcontroller module, output circuit, signal amplification circuit, and selection circuit. The signal input terminal of the selection circuit is electrically connected to the signal output terminal of the microcontroller module. The signal output terminal of the selection circuit is electrically connected to the interaction terminal of the signal amplification circuit. The signal output terminal of the signal amplification circuit is electrically connected to the signal input terminal of the output circuit. The signal output terminal of the output circuit is electrically connected to the signal input terminal of the microcontroller module. The signal output terminal of the sensor is electrically connected to the two signal terminals via signal lines.

[0007] Furthermore, the power module has two DC power output terminals.

[0008] Furthermore, the microcontroller module is equipped with electrically connected peripheral components, including resistors, capacitors, and a crystal oscillator. One end of the first resistor, one end of the second capacitor, the VDDA port of the microcontroller module, one end of the third capacitor, the VBAT port of the microcontroller module, one end of the fourth capacitor, the VDD port of the microcontroller module, one end of the fifth capacitor, and one end of the sixth capacitor are connected. One end of the second resistor is connected to one end of the crystal oscillator, one end of the seventh capacitor, and the PH0 port of the microcontroller module. The other end of the second resistor is connected to the other end of the crystal oscillator, and one end of the eighth capacitor is connected to... Connect the following terminals to the microcontroller module: PH1 port, the other end of the first capacitor, the other end of the second capacitor, the VSSA port of the microcontroller module, the other end of the seventh capacitor, the other end of the eighth capacitor, the other end of the third capacitor, the other end of the fourth capacitor, the VSS port of the microcontroller module, the other end of the fifth capacitor, the other end of the sixth capacitor, one end of the third resistor, the other end of the first resistor and one end of the first capacitor, the NRST port of the microcontroller module, and the other end of the third resistor to the BOOT0 port of the microcontroller module.

[0009] Furthermore, the signal amplification circuit includes electrically connected resistors, capacitors, diodes, and operational amplifiers. One end of the first resistor is connected to one end of the second resistor, the other end of the second resistor is connected to one end of the capacitor, the other end of the capacitor is connected to one end of the third resistor and the negative terminal of the diode, the other end of the third resistor is connected to one end of the fourth resistor and the non-inverting input port of the operational amplifier, one end of the fifth resistor is connected to the inverting input port of the operational amplifier, one end of the sixth resistor and one end of the seventh resistor, the other end of the seventh resistor is connected to one end of the eighth resistor and the output port of the operational amplifier, and the negative power input port of the operational amplifier is connected to the positive terminal of the diode, the other end of the first resistor, the other end of the fourth resistor, and the other end of the fifth resistor.

[0010] Furthermore, the output circuit includes an inverter, a high-speed optocoupler, a resistor, and a capacitor that are electrically connected. The signal output port of the inverter is connected to one end of the first resistor, the other end of the first resistor is connected to the signal input port of the high-speed optocoupler, the negative power input port of the high-speed optocoupler is connected to one end of the capacitor, the positive power input port of the high-speed optocoupler is connected to one end of the second resistor and the other end of the capacitor, and the signal output port of the high-speed optocoupler is connected to the other end of the second resistor.

[0011] Furthermore, the selection circuit includes electrically connected resistors, capacitors, MOSFETs, optocouplers, and transistors. One end of the first resistor and one end of the second resistor are connected to the base of the transistor. One end of the third resistor is connected to the collector of the transistor. The other end of the third resistor is connected to the negative power input terminal of the LED built into the optocoupler. One end of the first capacitor is connected to the positive power input terminal of the LED built into the optocoupler. The collector of the phototransistor built into the optocoupler is connected to one end of the second capacitor. The emitter of the phototransistor built into the optocoupler is connected to one end of the fourth resistor. The other end of the fourth resistor is connected to one end of the fifth resistor and the MOSFET. The other end of the fifth resistor is connected to the source of the MOSFET, the other end of the first capacitor, the other end of the second capacitor, the emitter of the transistor, and the other end of the second resistor.

[0012] Compared with existing technologies, the advantages of this utility model are as follows: Based on existing mature microcontroller module technology with digital display tube function, this utility model, with the joint action of related circuits, can compatiblely process signals input from magnetoresistive sensors or Hall sensors (for more flexible applications), effectively isolating external interference signals through optocouplers, etc.; a high-pass filter circuit composed of RC (resistive-capacitive) circuits effectively filters out DC component signals, allowing only varying AC signals to be input. The filtered small signal is then amplified by an operational amplifier circuit. The signal output from the operational amplifier is input to an inverter. Utilizing the Schmitt trigger circuit characteristics of the inverter, the signal amplitude is judged and distinguished again. Finally, the signal amplitude that meets the conditions is converted into corresponding high and low level signals, which are input to the input terminal of the high-speed optocoupler. After opto-isolation, the high-speed optocoupler outputs a clean and stable signal to the microcontroller module for digital speed display. Because the interference from external signals on speed detection is reduced, the displayed speed data is more accurate and reliable. In summary, this utility model has good application prospects. Attached Figure Description

[0013] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0014] Figure 1 This is a schematic diagram of the structure of this utility model.

[0015] Figure 2 , 3 This is the circuit diagram of this utility model.

[0016] Figure 4 This is a schematic diagram of a magnetoresistive sensor or Hall sensor structure. Detailed Implementation

[0017] Figure 1 , 2As shown in Figure 3, a novel speed display instrument includes a single-chip microcomputer module U1 with digital display tube function, a power supply module U6, an output circuit 1, a signal amplification circuit 2, and a selection circuit 3. The single-chip microcomputer module U1, the power supply module U6, the output circuit 1, the signal amplification circuit 2, and the selection circuit 3 are mounted on a circuit board inside the housing 4. The digital-to-analog display tube 5 of the single-chip microcomputer module is located outside the front opening of the housing 4.

[0018] Figure 1 , 2As shown in Figure 3, the power module U6 is an AC-to-DC power module with an input of 220V AC and two outputs of 3.3V and 5V DC. The microcontroller module U1 is also equipped with peripheral components connected via circuit board wiring: resistors R12, R3, R7; capacitors C1, C2, C3, C4, C5, C7, C8; and crystal oscillator X1. One end of the first resistor R12, one end of the second capacitor C6, pin 9 of the VDD / DA port of the microcontroller module U1; one end of the third capacitor C3, pin 1 of the VBAT port of the microcontroller module U1; one end of the fourth capacitor C1, pin 48 of the VDD port of the microcontroller module U1, pin 36 of the VDD port of the microcontroller module U1; one end of the fifth capacitor C2; one end of the sixth capacitor C8, pin 24 of the VDD port of the microcontroller module U1; one end of the second resistor R7, one end of the crystal oscillator X1; one end of the seventh capacitor C4, pin 5 of the PH0 port of the microcontroller module U1; and the other end of the second resistor R7, and crystal oscillator X1. On the other end, one end of the eighth capacitor C5 is connected to pin 6 of the PH1 port of the microcontroller module U1; the other end of the first capacitor C7 and the other end of the second capacitor C6 are connected to pin 8 of the VSSA port of the microcontroller module U1; the other end of the seventh capacitor C4 and the other end of the eighth capacitor C5 are connected to the other end of the third capacitor C3 and the other end of the fourth capacitor C1 are connected to pin 47 of the VSS port of the microcontroller module U1; the other end of the fifth capacitor C2 is connected to pin 35 of the VSS port of the microcontroller module U1; the other end of the sixth capacitor C8 is connected to pin 23 of the VSS port of the microcontroller module U1; one end of the third resistor R3 is connected to the other end of the first resistor R12 and one end of the first capacitor C7 are connected to pin 7 of the NRST port of the microcontroller module U1; and the other end of the third resistor R3 is connected to pin 44 of the BOOT0 port of the microcontroller module U1. The signal amplification circuit includes resistors R23, R24, R25, R26, R29, R30, R31, and R32, capacitor C12, diode D1, and operational amplifier U3, all connected via circuit board wiring. One end of the first resistor R32 is connected to one end of the second resistor R31. The other end of the second resistor R31 is connected to one end of capacitor C12. The other end of capacitor C12 is connected to one end of the third resistor R30 and the cathode of diode D1. The other end of the third resistor R30 is connected to one end of the fourth resistor R29 and the operational amplifier U3. The non-inverting input pin 3 of the op-amp U3 is connected to the following: one end of the fifth resistor R25 is connected to the inverting input pin 2 of the op-amp U3, one end of the sixth resistor R23, and one end of the seventh resistor R24; the other end of the seventh resistor R24 ​​is connected to one end of the eighth resistor R26 and the output pin 1 of the op-amp U3; the GND power input pin 4 of the op-amp U3 is connected to the positive terminal of diode D1, the other end of the first resistor R32, the other end of the fourth resistor R29, and the other end of the fifth resistor R25.The output circuit includes an inverter U4, a high-speed optocoupler U5, resistors R27 and R28, and a capacitor C11, all connected via circuit board wiring. Pin 4 of the inverter U4's signal output port is connected to one end of the first resistor R28, and the other end of the first resistor R28 is connected to pin 1 of the high-speed optocoupler U5's signal input port. Pins 3 and 4 of the high-speed optocoupler U5's negative power supply port are connected to one end of the capacitor C11. Pin 6 of the high-speed optocoupler U5's positive power supply input port is connected to one end of the second resistor R27 and the other end of the capacitor C11. Pin 5 of the high-speed optocoupler U5's signal output port is connected to the other end of the second resistor R27. The selection circuit includes resistors R18, R19, R20, R21, and R22, capacitors C9 and C10, MOSFET Q5, optocoupler U2, and transistor Q6, all connected via circuit board wiring. One end of the first resistor R21 and one end of the second resistor R22 are connected to the base of transistor Q6. One end of the third resistor R19 is connected to the collector of transistor Q6, and the other end of the third resistor R19 is connected to the negative power input terminal of the LED built into optocoupler U2. One end of the first capacitor C10 is connected to the LED built into optocoupler U2. The positive terminal of the diode is connected to the power input terminal. The collector of the phototransistor built into the optocoupler U2 is connected to one end of the second capacitor C9. The emitter of the phototransistor built into the optocoupler U2 is connected to one end of the fourth resistor R20. The other end of the fourth resistor R20 is connected to one end of the fifth resistor R18 and the gate of the MOSFET Q5. The other end of the fifth resistor R18 is connected to the source of the MOSFET Q5, the other end of the first capacitor C10, the other end of the second capacitor C9, the emitter of the transistor Q6, and the other end of the second resistor R22.

[0019] Figure 1 , 2As shown in Figures 3 and 4, the two ends of resistor R32 at the signal input terminal of the signal amplifier circuit and the two signal terminals IN+ and IN- are connected by wires. The interface of the signal terminals is located outside the opening at the rear end of the casing 4. The power input terminals 1 and 2 of the power module U6 are connected to the two poles of the AC 220V power supply by wires. The first power output terminals 3 and 4 of the power module U6 are connected to the two ends of capacitor C3 at the power input terminal of the microcontroller module U1, the two ends of resistor R27 at the first power input terminal of the output circuit, and the two ends of capacitor C10 at the first power input terminal of the selection circuit by wires. The second power output terminals 5 and 6 of the power module U6 are connected to the power input terminals 8 and 4 of operational amplifier U3, the two ends of capacitor C9 at the second power input terminal of the selection circuit, and the two ends of inverter U4 at the second power input terminal of the output circuit by wires. The other end of resistor R21 at the signal input terminal of the selection circuit is connected to pin 19 of port PB1 at the signal output terminal of the microcontroller module U1 by wires. The drain of MOSFET Q5 at the signal output terminal of the selection circuit and the other end of resistor R23 at the interaction terminal of the signal amplifier circuit are connected by a wire. The other end of resistor R26 at the signal output terminal of the signal amplifier circuit and pin 2 of inverter U4 at the signal input terminal of the output circuit are connected by a wire. Pin 5 of high-speed optocoupler U5 at the signal output terminal of the output circuit and pin 45 of port PB8 at the signal input terminal of microcontroller module U1 are connected by a wire. The signal output terminal of magnetoresistive sensor or Hall sensor 8 and the two signal terminals are connected by IN+ and IN- respectively via signal lines.

[0020] Figure 1 , 2 As shown in Figure 3, after the AC 220V power supply enters the power input terminal of the power module U6, the power module U6 outputs a stable DC 3.3V power supply through pins 3 and 4, which enters the power input terminal of the microcontroller module U1, the first power input terminal of the output circuit, and the first power input terminal of the selection circuit. The 5V DC power supply output from the second power output terminal 5 and pins 6 of the power module U6 enters the power input terminal of the signal amplification circuit, the second power input terminal of the selection circuit, and the second power input terminal of the output circuit, thus powering up and operating the above circuits.

[0021] Figure 1 , 2As shown in Figures 3 and 4, in this novel device, resistor R12 and capacitor C7 form the RC reset circuit of the microcontroller module U1 (its function is to make the capacitor equivalent to a short circuit at the moment of power-on, forming a high level, and resetting the microcontroller; after a few milliseconds, the capacitor is fully charged, the circuit becomes an open circuit, and the microcontroller enters the normal working state). Capacitors C4 and C5 and 8MHz crystal oscillator X1 form an external high-speed clock circuit (its function is to provide a stable clock signal for the microcontroller and ensure the normal operation of the microcontroller). Resistor R3 is a pull-down resistor for the working mode configuration (its function is to keep the level of pin 44 in a low level state, prevent the pin from being floating, and thus ensure the stability and reliability of the signal). Capacitors C1, C2, C3, C6, and C8 serve as filters. In the signal amplification circuit, the signal detected at the signal output terminal of the magnetoresistive sensor or Hall sensor 8 enters the signal input ports IN+ and IN- (the magnetoresistive sensor or Hall sensor is a passive device; its matching speed-measuring metal gear 6 is installed on the rear outer end of the turbine shaft 7, etc., and the magnetoresistive sensor or Hall sensor 8 is installed on the side end of the turbine casing, etc., with the detection surface of the magnetoresistive sensor or Hall sensor 8 and the speed-measuring metal gear 6 spaced a certain distance apart. When the turbine shaft 7 drives the speed-measuring metal gear 6 to rotate, the magnetic poles inside the magnetoresistive sensor or Hall sensor 8 change continuously. The magnetoresistive sensor or Hall sensor 8 outputs a dynamic AC small analog signal that changes with the rotational speed by detecting the changing magnetic poles). Resistor R32 is a 4.7K pull-down resistor (pull-down function, normally kept at the same potential as the negative terminal of the power supply when there is no input signal). Resistor R31 and capacitor C12 form an RC high-pass filter circuit to isolate the DC component in the input signal, allowing only the AC signal to pass; the high-pass filter cutoff frequency is calculated by the formula f=1 / (2πRC), where resistor R31 is 1K. Capacitor C12 has a capacitance of 22uF, and its theoretical cutoff frequency is calculated to be 7.2Hz. This means that any AC signal higher than 7.2Hz can be normally coupled and conducted to the non-inverting input pin 3 of the operational amplifier through capacitor C12. Diode D1 is a clamping protection diode with two main functions: first, to clamp negative AC voltage waveforms, using its forward voltage of 0.7V to clamp the voltage down to a minimum of -0.7V; second, to protect the non-inverting input of the operational amplifier, ensuring that the reverse voltage does not exceed the rated value and preventing damage to the operational amplifier U3 chip. Resistors R29 and R30 form a voltage divider circuit to divide the AC signal coupled from capacitor C12 and input it to the non-inverting input pin 3 of the operational amplifier.The operational amplifier U3 operates in a negative feedback state. Its external components, resistors R23, R24, and R25, form a feedback impedance network. Specifically, if the signal amplification circuit is connected to a Hall sensor, the generated signal is a 24V switching square wave signal. In this case, the amplification factor of operational amplifier U3 can be reduced. The resistor loop involved in the operation is R24 and R25. According to the amplification principle of operational amplifiers, the amplification bit is 1 + R24 / R25, which calculates to an amplification factor of 18.8 times. Resistor R23 does not need to participate in the operation. This can be achieved by controlling MOSFET Q5 to operate in the off state (since Q5 is off, the connection between resistor R23 and ground is disconnected, which is equivalent to floating, so resistor R23 does not participate in the circuit operation). If the input signal to the signal amplification circuit is a small signal from a magnetoresistive sensor, the amplification factor of the operational amplifier circuit needs to be dynamically increased. This is because, in low-speed rotation, the amplitude of the input AC small signal voltage may be less than 200mV. In this case, the amplification factor of the operational amplifier needs to be increased. Resistor R23 needs to be added to the feedback resistor network. Specifically, at this time, pin 19 of the microcontroller outputs a high level, causing transistor Q6 to conduct. The collector outputs a low level, which enters the negative terminal of the LED inside optocoupler U2, controlling optocoupler U2 to be powered on. The base of transistor Q6 is connected to two resistors, R21 and R22. Resistor R21 is the driving current-limiting resistor for the base of transistor Q6, and resistor R22 is the pull-down resistor for the base of transistor Q6 (pull-down function, maintaining the same potential as the negative terminal of the power supply when there is no control signal input). Resistor R19 is the current-limiting resistor for the LED on the primary side of optocoupler U2, and capacitor C10 is the filter capacitor for the power supply of the optocoupler. When the microcontroller's control pin 19 outputs a high level, transistor Q6 is powered on. The primary side of optocoupler U2 (where the built-in LED lights up) conducts, and the secondary side (where the built-in phototransistor) also conducts simultaneously. Pin 3 outputs a high level, which enters the gate of MOSFET Q5. MOSFET Q5 receives a 5V operating voltage and conducts. Resistor R20 is the current-limiting resistor for MOSFET Q5, and resistor R18 is the source pull-down resistor for MOSFET Q5 (pull-down function; when there is no control signal input, it maintains the same potential as the negative power supply). After MOSFET Q5 conducts, resistor R23 is connected in parallel with R24 and R25 to form a feedback impedance network, changing the overall impedance of the signal amplification circuit, thereby changing the signal amplification factor of operational amplifier U3. The amplification factor of the entire negative feedback resistor network at this time is 1 + (R24 / (R23 / / R25)), which calculates to be 54.4 times.

[0022] Figure 1 , 2As shown in Figure 3, the amplified voltage signal output from pin 1 of operational amplifier U3 is current-limited by resistor R26 and enters pin 2 of inverter U4. Because the inverter internally uses a Schmitt trigger circuit, only values ​​>0.7*Vcc (0.7*5V=3.5V) are considered high, and only values ​​<0.3*Vcc (0.3*5V=1.5V) are considered low. For voltage values ​​between 1.5V and 3.5V, the inverter will not operate and will maintain the previous voltage level. This allows for stable differentiation of the effective signal amplitude range (the effective signal amplitude function is as follows: only signals >3.5V are considered high, signals below 1.5V are considered low, and voltages between 1.5V and 3.5V are treated the same as the previous voltage state, serving as a filter to reduce the influence of interference signals). The output pin 4 of inverter U4 outputs a voltage level opposite to that of pin 2, which drives the primary LED of high-speed optocoupler U5 (the LED built into the optocoupler is connected between pins 1 and 3) through current-limiting resistor R28. The secondary pin 5 of high-speed optocoupler U5 (the phototransistor built into the optocoupler is connected between pins 6 and 5) outputs an isolated switching signal to pin 45 of microcontroller module U1. Because pin 5 of optocoupler U5 is an open-drain output pin (with capacitor C11 acting as a filter), an external pull-up resistor is required. R27 is the pull-up resistor. Under its own power, microcontroller module U1 counts the switching signals output by the optocoupler and displays them on a multi-dimensional LED digital tube. By observing the changes in the numbers, the operator can obtain the real-time rotational speed of the turbine shaft.

[0023] Figure 1 , 2As shown in Figures 3 and 4, through the above technical solution, this new invention, based on existing mature single-chip microcontroller module technology with digital display tube function, can dynamically change the impedance matching of the signal amplification circuit, thus flexibly adapting to different input signals (compatible with processing signals input from magnetoresistive sensors or Hall sensors (for more flexible applications)). In the prior art, for magnetoresistive sensors, because they are passive devices, they induce a small AC signal by detecting changes in the internal magnetic poles during turbine rotation. This signal waveform is easily interfered with by strong magnetic fields such as motors, and the waveform is easily distorted. Moreover, the signal amplitude is very small (generally less than 200mV at low speeds), and the signal amplitude also changes with the motor speed. When the speed is high, the signal amplitude is large, and when the speed is low, the amplitude is small. Furthermore, the signal is easily affected by interference from the motor's magnetic field, and interference noise is easily introduced. This invention's signal amplification circuit employs an electrical isolation scheme for the input signal, effectively isolating external interference signals from other circuits. A high-pass filter circuit composed of RC (resistive-capacitive) circuits effectively filters out DC components, allowing only varying AC signals to be input. The filtered small signal is then amplified by an operational amplifier. The output signal from the operational amplifier is input to an inverter. Utilizing the Schmitt trigger circuit characteristics of the inverter, the signal amplitude is further judged and distinguished. Finally, the signal amplitude meeting the conditions is converted into corresponding high and low level signals, which are input to the input terminal of a high-speed optocoupler. After opto-isolation, the high-speed optocoupler outputs a clean and stable signal to the microcontroller module. Therefore, this invention can accurately detect and display the turbine speed, providing more accurate and reliable speed data. In practical applications, it can stably detect turbine shaft speeds as low as 60 rpm, exceeding any existing product of the same type (which typically >= 100 rpm). The component models in the circuit diagram have been standardized and will not be repeated here.

[0024] The foregoing has shown and described the basic principles, main features, and advantages of this utility model. It will be apparent to those skilled in the art that this utility model is limited to the details of the exemplary embodiments described above, and that it can be implemented in other specific forms without departing from the spirit or basic characteristics of this utility model. Therefore, the embodiments should be considered exemplary and non-limiting in all respects. The scope of this utility model is defined by the appended claims rather than the foregoing description, and thus all variations falling within the meaning and scope of equivalents of the claims are intended to be included within this utility model.

[0025] Furthermore, it should be understood that although this specification describes the embodiments, the embodiments do not necessarily contain only one independent technical solution. This way of describing the specification is only for clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in the embodiments can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A novel speed display instrument, comprising a microcontroller module and a power supply module, characterized in that, It also includes an output circuit, a signal amplification circuit, and a selection circuit. The microcontroller module, power supply module, output circuit, signal amplification circuit, and selection circuit are installed inside the housing. The signal input terminal of the signal amplification circuit is electrically connected to the two signal terminals, and the interface of the signal terminals is located outside the rear end of the housing. The power output terminal of the power supply module is electrically connected to the power input terminals of the microcontroller module, output circuit, signal amplification circuit, and selection circuit. The signal input terminal of the selection circuit is electrically connected to the signal output terminal of the microcontroller module. The signal output terminal of the selection circuit is electrically connected to the interaction terminal of the signal amplification circuit. The signal output terminal of the signal amplification circuit is electrically connected to the signal input terminal of the output circuit. The signal output terminal of the output circuit is electrically connected to the signal input terminal of the microcontroller module. The signal output terminal of the sensor is electrically connected to the two signal terminals via signal lines.

2. The novel speed display instrument according to claim 1, characterized in that, The power module has two DC power output terminals.

3. The novel speed display instrument according to claim 1, characterized in that, The microcontroller module is equipped with electrically connected peripheral components: resistors, capacitors, and a crystal oscillator. One end of the first resistor, one end of the second capacitor, the VDD / DA port of the microcontroller module, one end of the third capacitor, the VBAT port of the microcontroller module, one end of the fourth capacitor, the VDD port of the microcontroller module, one end of the fifth capacitor, and one end of the sixth capacitor are connected. One end of the second resistor is connected to one end of the crystal oscillator, one end of the seventh capacitor, and the PH0 port of the microcontroller module. The other end of the second resistor is connected to the other end of the crystal oscillator. One end of the eighth capacitor is connected to the microcontroller... Connect the module's PH1 port to the other end of the first capacitor, the other end of the second capacitor, the VSSA port of the microcontroller module, the other end of the seventh capacitor, the other end of the eighth capacitor, the other end of the third capacitor, the other end of the fourth capacitor, the VSS port of the microcontroller module, the other end of the fifth capacitor, the other end of the sixth capacitor, and one end of the third resistor. Connect the other end of the first resistor and one end of the first capacitor to the NRST port of the microcontroller module. Connect the other end of the third resistor to the BOOT0 port of the microcontroller module.

4. A novel speed display instrument according to claim 1, characterized in that, The signal amplification circuit includes electrically connected resistors, capacitors, diodes, and an operational amplifier. One end of the first resistor is connected to one end of the second resistor. The other end of the second resistor is connected to one end of the capacitor. The other end of the capacitor is connected to one end of the third resistor and the negative terminal of the diode. The other end of the third resistor is connected to one end of the fourth resistor and the non-inverting input port of the operational amplifier. One end of the fifth resistor is connected to the inverting input port of the operational amplifier, one end of the sixth resistor, and one end of the seventh resistor. The other end of the seventh resistor is connected to one end of the eighth resistor and the output port of the operational amplifier. The negative power input port of the operational amplifier is connected to the positive terminal of the diode, the other end of the first resistor, the other end of the fourth resistor, and the other end of the fifth resistor.

5. A novel speed display instrument according to claim 1, characterized in that, The output circuit includes an inverter, a high-speed optocoupler, a resistor, and a capacitor that are electrically connected. The signal output port of the inverter is connected to one end of the first resistor, and the other end of the first resistor is connected to the signal input port of the high-speed optocoupler. The negative power input port of the high-speed optocoupler is connected to one end of the capacitor. The positive power input port of the high-speed optocoupler is connected to one end of the second resistor and the other end of the capacitor. The signal output port of the high-speed optocoupler is connected to the other end of the second resistor.

6. A novel speed display instrument according to claim 1, characterized in that, The selection circuit includes electrically connected resistors, capacitors, MOSFETs, optocouplers, and transistors. One end of the first resistor and one end of the second resistor are connected to the base of the transistor. One end of the third resistor is connected to the collector of the transistor. The other end of the third resistor is connected to the negative power input terminal of the LED built into the optocoupler. One end of the first capacitor is connected to the positive power input terminal of the LED built into the optocoupler. The collector of the phototransistor built into the optocoupler is connected to one end of the second capacitor. The emitter of the phototransistor built into the optocoupler is connected to one end of the fourth resistor. The other end of the fourth resistor is connected to one end of the fifth resistor and the MOSFET. The other end of the fifth resistor is connected to the source of the MOSFET, the other end of the first capacitor, the other end of the second capacitor, the emitter of the transistor, and the other end of the second resistor.

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