Alarm device for testing rated rotating speed service life of fan

Abstract

The utility model relates to the technical field of fan rated speed service life testing, in particular to an alarm device for testing fan rated speed service life. The alarm device comprises a rotating speed-to-voltage circuit used for converting the rotating speed of a to-be-detected fan into an electric signal; the voltage comparison circuit is used for comparing the electric signal output by the rotating speed-to-voltage circuit with a preset reference voltage and outputting a comparison result; and the alarm circuit is used for sending an alarm signal according to the comparison result. According to the timing device for testing the rated rotating speed service life of the fan, the problems existing in the speed measurement process of the fan are solved, and the efficiency and the accuracy of fan service life testing are improved.

Description

Technical Field

[0001] This utility model relates to the field of fan rated speed life testing technology, specifically an alarm device for testing the rated speed life of a fan. Background Technology

[0002] The rated speed life test of a fan verifies whether the operating life of the equipment's fan meets the design requirements, requiring that the fan speed not be lower than 70% of the rated speed. In the past, the speed was usually tested by using a laser counter and attaching reflectors to the fan blades. However, this method can only capture the speed data momentarily and cannot monitor the speed data for a long time to ensure that it always meets the requirements, nor can it accurately measure the qualified operating time of the fan. Utility Model Content

[0003] This invention provides an alarm device for testing the rated speed life of a fan to solve the technical problem of not being able to monitor fan speed data for a long time.

[0004] The technical solution of this utility model to solve the above-mentioned technical problems is as follows:

[0005] An alarm device for testing the rated speed life of a fan is provided. The alarm device includes a speed-to-voltage circuit for converting the speed of the fan under test into an electrical signal; a voltage comparison circuit for comparing the electrical signal output by the speed-to-voltage circuit with a preset reference voltage and outputting the comparison result; and an alarm circuit for issuing an alarm signal based on the comparison result.

[0006] Furthermore, the speed-to-voltage circuit includes an adjustable DC power supply and a micro generator. The shaft of the micro generator is coaxially connected to the shaft of the fan under test. The adjustable DC power supply is used to provide the rated voltage to the fan under test. When the fan under test is running, the micro generator outputs a voltage signal proportional to the fan speed.

[0007] Furthermore, the voltage comparison circuit includes a comparator and an adjustable resistor. The non-inverting input of the comparator receives the voltage signal output by the micro generator, and the adjustable resistor adjusts the voltage at the inverting input of the comparator to 70% of the output voltage of the micro generator when the fan under test is at its rated speed.

[0008] Furthermore, the alarm circuit includes an alarm device and a driving circuit, wherein the driving circuit controls the operating state of the alarm device based on the output of the comparator.

[0009] Furthermore, the output voltage + pin of the micro generator is connected to the non-inverting input of the comparator, and the inverting input of the comparator is connected to the positive terminal of the adjustable DC power supply through the adjustable resistor. The adjustable resistor is used to precisely adjust the voltage value of the inverting input to ensure that the voltage value is 70% of the output voltage of the micro generator when the fan under test is at its rated speed.

[0010] Furthermore, the comparator is an LM311, and its output pin is connected to the input of the alarm circuit. The output pin outputs a high level when the voltage value at the non-inverting input is greater than or equal to the voltage value at the inverting input, and outputs a low level when the voltage value at the non-inverting input is less than the voltage value at the inverting input.

[0011] Furthermore, the alarm circuit includes a pull-up resistor, one end of which is connected to the output pin of the comparator and the other end is connected to the positive terminal of the adjustable DC power supply. The pull-up resistor is used to ensure that the driving circuit provides sufficient voltage when the comparator outputs a high level to drive the alarm to work.

[0012] Furthermore, the alarm is an audible and visual alarm, which is activated when the drive circuit receives a high-level signal and emits an audible and visual alarm signal to indicate that the speed of the fan under test is lower than a preset value.

[0013] Furthermore, the alarm device also includes a timing circuit, which includes a relay timer and a pull-up resistor. The relay timer accumulates the effective running time of the fan based on the output of the comparator and stops timing when the comparator outputs a low level. The timing circuit is also connected to the alarm circuit. When the timing circuit stops timing and the alarm circuit is activated, the timing circuit outputs the fan's operating life data.

[0014] Furthermore, the output voltage range of the adjustable DC power supply is 5V to 12V to adapt to the rated voltage requirements of different models of the fan under test. The voltage value at the inverting input terminal of the comparator can be adjusted within the output voltage range of the adjustable DC power supply by the adjustable resistor to ensure that the voltage value is 70% of the output voltage of the micro generator at the rated speed of the fan under test.

[0015] The beneficial effects of this utility model are:

[0016] This invention solves the problems existing in fan speed measurement by providing a timing device for testing the rated speed life of a fan, thus improving the efficiency and accuracy of fan life testing. Specifically, this invention uses a speed-to-voltage circuit to convert the fan speed under test into an electrical signal. A voltage comparison circuit monitors the fan speed in real time and compares the speed signal with a preset reference voltage. When the fan speed is lower than 70% of the rated speed, the voltage comparison circuit outputs a low-level signal, causing the timing circuit to stop timing. This process achieves continuous and automatic monitoring of fan speed, eliminating the instantaneous data capture and monitoring blind spots in traditional manual speed measurement methods, ensuring the continuity of speed data during the test. Simultaneously, through voltage comparison and timing functions, this invention can accurately record the cumulative running time of the fan within the qualified speed range, thus providing a reliable basis for fan life assessment. This not only simplifies the testing process and reduces the workload of operators but also improves the accuracy of test data, providing technical support for fan quality control and improvement. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the circuit structure of this utility model;

[0018] Figure 2 This is a schematic diagram of the pinout of the LM311 comparator of this utility model;

[0019] Figure 3 This is a schematic diagram of the operation process of this utility model. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this utility model, and should not be construed as limiting this utility model. Furthermore, it should be understood that the specific embodiments described herein are merely for explaining this utility model and are not intended to limit this utility model.

[0021] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection, an electrical connection, or a connection that allows for communication; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0022] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0023] The following disclosure provides numerous different embodiments or examples for implementing various structures of the present invention. To simplify the disclosure, specific examples of components and arrangements are described below. These are merely examples and are not intended to limit the scope of the invention. Furthermore, reference numerals and / or letters may be repeated in different examples; such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed. In addition, examples of various specific processes and materials are provided in this invention; however, those skilled in the art will recognize the application of other processes and / or the use of other materials.

[0024] like Figures 1 to 3 As shown, the present invention provides the following preferred embodiments:

[0025] Example 1

[0026] To address the problems of cumbersome procedures, inability to monitor fan speed data for extended periods, and inability to accurately measure the qualified operating time of fans in existing manual speed measurement methods, this embodiment proposes a timing device for testing the rated speed life of a fan. This device mainly includes a speed-to-voltage conversion circuit, a voltage comparison circuit, and a timing circuit. Through the coordinated operation of these circuits, real-time monitoring and effective timing of fan speed are achieved.

[0027] First, the design and implementation of the speed-to-voltage circuit is fundamental to this device. This circuit consists of an adjustable DC power supply (DC1) and a micro-generator (②). The shaft of the fan under test (①) is connected to the shaft of the micro-generator via a sleeve, ensuring coaxiality. Specifically, the shaft of the micro-generator is fitted onto the sleeve, with the bottom end of the sleeve adhered to the center of the fan's shaft, aligning the generator's shaft with the fan's shaft on the same center line. In this way, the speed of the fan under test directly drives the micro-generator's shaft, which converts the speed into a proportional voltage signal. It's important to understand that this method not only simplifies the speed monitoring process but also ensures the real-time performance and accuracy of the data. The output voltage of the micro-generator is connected to the non-inverting input of the voltage comparator circuit (pin 2 of the LM311 comparator) via its + pin.

[0028] Furthermore, the voltage comparator circuit is designed to compare the voltage signal output by the micro-generator with a preset reference voltage. This circuit consists of an LM311 comparator IC and peripheral circuitry such as an adjustable resistor R1. The adjustable resistor R1 is used to adjust the voltage value at the inverting input terminal of the comparator (i.e., pin 3 of the LM311 comparator) to be 70% of the micro-generator output voltage at the rated speed of the fan under test. In specific operation, one end of R1 is connected to the positive terminal of the adjustable DC power supply DC1, and the other end is connected through pin 3 of the comparator. By adjusting the resistance value of R1, it can be ensured that the voltage value at pin 3 is 70% of the micro-generator output voltage at the rated speed of the fan under test. When the fan under test is operating normally at its rated voltage, the voltage signal output by the micro-generator is input to the comparator through the non-inverting input terminal. The comparator compares this voltage signal with the reference voltage at the inverting input terminal. If the voltage value at the non-inverting input terminal is greater than or equal to the reference voltage value at the inverting input terminal, the comparator's output pin 7 will output a high-level signal. It is important to understand that the voltage comparator circuit is designed to ensure that the timing circuit can be accurately started and begin timing when the fan speed is normal.

[0029] Furthermore, the timing circuit is designed to accurately record the effective running time of the fan. This circuit consists of a relay timer J1 and a pull-up resistor R2. The start and stop of the relay timer J1 are controlled by the output signal of the voltage comparator circuit. Specifically, pin 7 of the LM311 comparator is connected to the input of the relay timer J1 through the pull-up resistor R2. When the comparator outputs a high-level signal, the voltage provided by the pull-up resistor R2 is sufficient to drive the relay timer J1 to start working and timing. When the speed of the fan under test drops below 70% of its rated speed, the voltage signal output by the micro-generator will be lower than the reference voltage at the inverting input of the comparator. At this time, pin 7 of the comparator outputs a low-level signal, and the relay timer J1 stops timing. It is important to understand that the timing circuit design not only ensures the accuracy of timing but also stops timing promptly when the fan speed is unacceptable, avoiding the recording of invalid time.

[0030] Furthermore, to improve the applicability and reliability of the device, the adjustable DC power supply DC1 has an output voltage range of 5V to 12V to accommodate the rated voltage requirements of different fan models. In practical operation, the output voltage of DC1 is adjusted to the corresponding value based on the rated voltage of the fan under test. For example, if the rated voltage of the fan under test is 12V, the output voltage of DC1 is adjusted to 12V. It is important to understand that the design of the adjustable DC power supply allows the device to be widely used with different types of fans, improving its versatility and flexibility.

[0031] Furthermore, to ensure the accuracy of the voltage comparison, a precise adjustable resistor R1 and a high-precision comparator can be used. Specifically, the resistance of R1 is set to 5KΩ, and through fine adjustment, the voltage value at the inverting input of the comparator can be accurately adjusted to 70% of the output voltage of the micro-generator at the rated speed of the fan under test. The LM311 comparator has high sensitivity and stability, and can output accurate comparison results even with small voltage changes. It should be understood that the selection and use of high-precision resistors and comparators ensures the accuracy of the voltage comparison, further improving the overall performance of this invention.

[0032] Furthermore, the pull-up resistor R2 ensures that the high-level signal output by the comparator can effectively drive the relay timer J1. R2 is set to 2KΩ; when the comparator outputs a high level, the voltage provided by R2 is sufficient to meet the operating requirements of the relay timer, ensuring accurate start and stop of the timing circuit. It is important to understand that the proper selection of the pull-up resistor not only guarantees the reliable operation of the relay timer but also avoids malfunctions or inaccurate timing due to insufficient voltage.

[0033] Furthermore, to improve the portability and ease of use of the device, a display screen can be added. The screen displays the fan speed and cumulative running time in real time, allowing operators to intuitively understand various data during the test. In practice, a small LCD screen can be added to the output terminals of the voltage comparison circuit and the timing circuit. The comparator's output signal and the relay timer's timing result are displayed on the screen in real time via a corresponding drive circuit. It's important to understand that the addition of the display screen not only improves the device's visualization but also facilitates real-time monitoring and data recording by operators, further enhancing the efficiency and accuracy of the test.

[0034] Furthermore, to ensure the stability and reliability of the device, overvoltage protection and temperature compensation circuits can be added. The overvoltage protection circuit prevents damage caused by excessive input voltage. Specifically, a Zener diode and a fuse can be added to the output of the adjustable DC power supply DC1. When the input voltage exceeds the set value, the Zener diode conducts, and the fuse blows, thus protecting the device. The temperature compensation circuit maintains the stability of the micro-generator's output voltage under different ambient temperatures. Specifically, a temperature sensor and a compensation resistor can be added to the output of the micro-generator. The circuit design ensures that the output voltage of the micro-generator remains consistent under different temperatures. It is important to understand that the addition of these features not only improves the stability and reliability of the device but also enables it to operate normally under a wider range of environmental conditions.

[0035] Through the above design, this embodiment provides a device capable of continuously and automatically monitoring fan speed and accurately timing, solving the problems existing in manual speed measurement methods. Specifically, the speed-to-voltage circuit converts the fan speed into an electrical signal in real time, and the voltage comparison circuit compares this electrical signal with a preset reference voltage. When the fan speed is lower than 70% of the rated speed, the timing circuit can stop timing in time, thereby accurately recording the qualified operating time of the fan. The benefits of this embodiment are that it not only simplifies the testing process and improves testing efficiency, but also ensures the accuracy of test data, providing technical support for fan lifespan assessment. In addition, the versatility and ease of use of the testing device are also improved, enabling it to be widely used in various types of fan testing.

[0036] Example 2

[0037] To further optimize the testing capabilities of this invention, this embodiment adds a data recording and analysis module to the original design. This module consists of a microprocessor and a data storage device, used to record the fan's rotational speed and cumulative running time in real time, and to perform data analysis. Specifically, the microprocessor can be an ARM Cortex-M3 chip, and the data storage device can be an SPI interface flash memory chip. The microprocessor converts the output signal (high or low level) of the voltage comparator circuit into a digital signal via an A / D converter and stores it in the data storage device. Furthermore, the microprocessor can also transmit data to external devices, such as computers or cloud servers, via a serial communication interface for further data analysis and management.

[0038] Specifically, the addition of a data recording and analysis module enables the device to record and store test data over extended periods. During testing, the microprocessor monitors the output signal of the voltage comparison circuit in real time. When the output is high, the fan speed and time are recorded; when the output is low, recording stops and the time point when the fan speed fails to meet the standard is marked. This data is converted into digital signals by an A / D converter and stored in the data memory. It is important to understand that the data recording and analysis module improves the integrity and traceability of the test data.

[0039] Furthermore, the microprocessor can analyze the recorded data to generate detailed test reports. Specifically, the microprocessor can use built-in algorithms to calculate parameters such as the fan's average speed, maximum speed, minimum speed, and speed fluctuation range, and display these parameters in graphical form. In addition, the microprocessor can calculate the fan's cumulative operating time at its rated speed and compare it with a preset lifespan to generate a lifespan assessment report. These reports can be transmitted to external devices via a serial communication interface, allowing operators to easily view and analyze the test results. It's important to understand that the addition of the data recording and analysis modules not only provides abundant test data but also enhances the device's intelligence and automation, further improving testing efficiency and accuracy.

[0040] Furthermore, to improve the portability and ease of use of the device, a wireless communication module is also included in this embodiment. The wireless communication module can employ Wi-Fi or Bluetooth technology to wirelessly transmit test data to the operator's mobile device, such as a mobile phone or tablet. Specifically, a Wi-Fi or Bluetooth module can be connected to the communication interface of the microprocessor to transmit test data to the operator's mobile device in real time via a wireless network. The operator can view the test data and lifespan assessment report through a dedicated mobile application or web interface for real-time monitoring and management. It is important to understand that the addition of the wireless communication module not only improves the ease of use of the device but also facilitates remote monitoring and data analysis by the operator, further enhancing the flexibility of the testing process.

[0041] This embodiment provides a device capable of continuously and automatically monitoring fan speed and recording and analyzing test data through optimized design. Specifically, the addition of a data recording and analysis module enables the device to record and store test data over extended periods and generate detailed test reports, improving the integrity and traceability of the test data. The inclusion of a wireless communication module enhances the device's usability, facilitating remote monitoring and data analysis by operators. This embodiment not only further improves testing efficiency and accuracy but also provides richer data support for evaluating fan lifespan and improving products, giving it greater practical value in real-world applications.

[0042] Example 3

[0043] To address the complexity and uncertainty of environmental conditions during fan testing, this embodiment incorporates an environmental monitoring module. This module comprises temperature, humidity, and pressure sensors, used to monitor parameters such as temperature, humidity, and pressure in the test environment in real time, ensuring these parameters remain within reasonable ranges during fan rated speed testing. Specifically, the temperature sensor can be an NTC thermistor, the humidity sensor can be a capacitive humidity sensor, and the pressure sensor can be a piezoresistive pressure sensor. The output signals from these sensors are amplified and converted to digital values ​​by an A / D converter, which then processes and analyzes these signals to generate an environmental monitoring report.

[0044] Specifically, a temperature sensor is added to monitor the temperature of the testing environment in real time. In practice, an NTC thermistor is installed near a fan, and by monitoring temperature changes around the fan, the temperature is ensured to remain within a reasonable range during testing. A microprocessor converts the output signal of the NTC thermistor into a digital signal via an A / D converter and records and analyzes it in real time. When the ambient temperature exceeds a preset upper limit or falls below a preset lower limit, the microprocessor issues an alarm signal, reminding the operator to adjust the testing environment. It is important to understand that the addition of the temperature sensor not only ensures temperature stability during testing but also avoids testing errors caused by temperature variations, further improving the accuracy of the test.

[0045] Furthermore, a humidity sensor is added to monitor the humidity of the test environment in real time. In practice, a capacitive humidity sensor is installed near a fan to monitor humidity changes around the fan, ensuring the humidity remains within a reasonable range during testing. The microprocessor converts the output signal from the capacitive humidity sensor into a digital signal via an A / D converter and records and analyzes it in real time. When the ambient humidity exceeds a preset upper limit or falls below a preset lower limit, the microprocessor issues an alarm signal, reminding the operator to adjust the test environment. It's important to understand that the addition of the humidity sensor not only ensures stable humidity during testing but also avoids test errors caused by humidity changes, further improving test accuracy.

[0046] Furthermore, a pressure sensor is added to monitor the pressure of the testing environment in real time. In practice, a piezoresistive pressure sensor is installed near the fan. By monitoring pressure changes in the environment around the fan, the pressure is ensured to remain within a reasonable range during testing. The microprocessor converts the output signal of the piezoresistive pressure sensor into a digital signal via an A / D converter and records and analyzes it in real time. When the ambient pressure exceeds a preset upper limit or falls below a preset lower limit, the microprocessor issues an alarm signal, reminding the operator to adjust the testing environment. It is important to understand that the addition of the pressure sensor not only ensures pressure stability during testing but also avoids testing errors caused by pressure changes, further improving the accuracy of the test.

[0047] Furthermore, to ensure the real-time performance of the environmental monitoring module, the microprocessor can employ multi-tasking technology to process both speed and environmental signals simultaneously. Specifically, the microprocessor can be configured with multiple interrupt service routines to handle speed, temperature, humidity, and pressure signals respectively. Through interrupts, the microprocessor can quickly switch between different tasks, ensuring real-time processing and analysis of all signals. It's important to understand that the adoption of multi-tasking technology not only improves the real-time performance of the environmental monitoring module but also enhances the overall performance and stability of the device.

[0048] This embodiment provides a device capable of continuously and automatically monitoring fan speed and real-time monitoring of the test environment through optimized design. Specifically, the addition of an environmental monitoring module enables the device to monitor parameters such as temperature, humidity, and pressure in the test environment in real time, ensuring that these parameters remain within a reasonable range during fan rated speed testing. The microprocessor processes both speed and environmental signals simultaneously using multitasking technology, ensuring the real-time nature and reliability of all data. The benefits of this embodiment are that it not only further improves the accuracy and stability of the test but also provides more comprehensive data support for evaluating fan lifespan, making it practically valuable in tests under complex environmental conditions.

[0049] The beneficial effects of this utility model are specifically reflected in the fact that the above description is only a preferred embodiment of this utility model and is not intended to limit this utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. An alarm device for testing the rated speed life of a fan, characterized by, The alarm device comprises a rotating speed-voltage conversion circuit for converting the rotating speed of the fan to be tested into an electric signal; a voltage comparison circuit for comparing the electric signal outputted by the rotating speed-voltage conversion circuit with a preset reference voltage and outputting a comparison result; an alarm circuit for sending an alarm signal according to the comparison result.

2. The alarm device for testing the rated speed life of a fan according to claim 1, wherein The rotating speed-voltage conversion circuit comprises an adjustable DC power supply and a micro generator, the rotating shaft of the micro generator is coaxially connected with the rotating shaft of the fan to be tested, the adjustable DC power supply is used for providing a rated voltage for the fan to be tested, and the micro generator outputs a voltage signal proportional to the rotating speed of the fan when the fan to be tested is running.

3. The alarm device for testing the rated speed life of a fan according to claim 2, wherein The voltage comparison circuit comprises a comparator and an adjustable resistor, the positive input end of the comparator receives the voltage signal outputted by the micro generator, and the voltage value of the negative input end of the comparator is adjusted to 70% of the voltage outputted by the micro generator when the fan to be tested rotates at a rated speed by the adjustable resistor.

4. The alarm device for testing the rated speed life of a fan according to claim 3, wherein The alarm circuit comprises an alarm and a driving circuit, and the driving circuit controls the working state of the alarm according to the output result of the comparator.

5. The alarm device for testing the rated speed life of a fan according to claim 4, wherein The output voltage + pin of the micro generator is connected to the positive input end of the comparator, the negative input end of the comparator is connected to the positive pole of the adjustable DC power supply through the adjustable resistor, and the adjustable resistor is used for accurately adjusting the voltage value of the negative input end to ensure that the voltage value is 70% of the voltage outputted by the micro generator when the fan to be tested rotates at a rated speed.

6. The alarm device for testing the rated speed life of a fan according to claim 4, wherein The comparator is a model LM311, the output pin of the comparator is connected to the input end of the alarm circuit, and the output pin outputs a high level when the voltage value of the positive input end is greater than or equal to the voltage value of the negative input end, and outputs a low level when the voltage value of the positive input end is less than the voltage value of the negative input end.

7. The alarm device for testing the rated speed life of a fan according to claim 4, wherein The alarm circuit comprises a pull-up resistor, one end of the pull-up resistor is connected to the output pin of the comparator, the other end of the pull-up resistor is connected to the positive pole of the adjustable DC power supply, and the pull-up resistor is used for ensuring that the driving circuit provides sufficient voltage to drive the alarm to work when the comparator outputs a high level.

8. The alarm device for testing the rated speed life of a fan according to claim 4, wherein The alarm is an audible and light alarm, the audible and light alarm is started when the driving circuit receives a high level signal, and sends an audible and light alarm signal to prompt that the rotating speed of the fan to be tested is lower than a preset value.

9. The alarm device for testing the rated speed life of a fan according to claim 3, wherein The alarm device further comprises a timing circuit, the timing circuit comprises a relay timer and a pull-up resistor, the relay timer accumulates the effective running time of the fan according to the output result of the comparator and stops timing when the comparator outputs a low level, and the timing circuit is further connected to the alarm circuit, and the timing circuit outputs the running life data of the fan when the timing circuit stops timing and the alarm circuit is started.

10. The alarm device for testing the rated speed life of a fan according to claim 3, wherein The output voltage range of the adjustable DC power supply is 5V to 12V to adapt to the rated voltage requirements of different models of the fan to be tested, and the voltage value of the negative input end of the comparator can be adjusted within the output voltage range of the adjustable DC power supply by the adjustable resistor to ensure that the voltage value is 70% of the voltage outputted by the micro generator when the fan to be tested rotates at a rated speed.

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