The liquid pressure sensor is one of the core components of the servo level gauge, which can convert the liquid pressure into electrical signals for measurement. Liquid pressure sensor usually consists of pressure measuring unit, signal conversion chip and output interface. The pressure measuring unit adopts a specially designed structure, which can sense the pressure of the liquid and convert the pressure into mechanical displacement or electrical signal. The signal conversion chip processes and amplifies the mechanical displacement or electrical signal, and finally outputs an electrical signal proportional to the liquid pressure. The output interface transmits the signal to the signal processing circuit.
 The working principle of the liquid pressure sensor mainly includes the principle of force balance and the principle of elastic deformation. When the liquid is applied to the sensing surface of the sensor, the sensing surface will be subject to the pressure of the liquid, and the elastic element inside the sensor will undergo certain deformation, which will cause the electrical signal output by the sensor to change. The pressure and level of liquid can be determined by measuring the change of electrical signal.
 The liquid pressure sensor plays an important role in the servo level gauge. It can monitor the pressure change of the liquid in real time, so as to accurately measure the level.
 2. Signal processing circuit
 The signal processing circuit is the key component of the servo level gauge, which is mainly responsible for receiving the electrical signal from the liquid pressure sensor, and amplifying, filtering and conditioning the signal to facilitate the control system to analyze and process the signal.
 Signal processing circuit is usually composed of amplification circuit, filtering circuit and conditioning circuit. The amplification circuit amplifies the input signal, increases the amplitude of the signal, and improves the reliability and sensitivity of the signal. The filter circuit can filter out the clutter and interference signals in the input signal, and ensure the accuracy and stability of the output signal. The conditioning circuit adjusts the amplified and filtered signals to meet the requirements of the control system.
 The design of the signal processing circuit needs to consider the working environment and measurement requirements of the servo level gauge, as well as the accuracy and reliability of the signal. A good signal processing circuit can improve the measurement accuracy and stability of servo level gauge.
 3. Control system
 The control system is the core part of the servo level gauge. It calculates and judges according to the signal output from the signal processing circuit, and controls the operation of the output device.
 The control system mainly includes microprocessor, algorithm implementation module and control strategy. The microprocessor is the core of the control system, which is responsible for receiving and processing signals from the signal processing circuit, executing algorithms and controlling the actions of the output device. The algorithm implementation module refers to a set of algorithms and methods for processing the measured data, which is used to determine the level of liquid. The control strategy is to select appropriate control methods and parameters according to the measured data and user requirements to achieve accurate control of the liquid level.
 The working principle of the control system is to convert the signal output from the signal processing circuit into the control signal, and realize the measurement and control of the liquid level by adjusting the operating state of the output device. The performance and stability of the control system have an important impact on the measurement accuracy and reliability of the servo level gauge.
 4. Output device
 The output device is the final working result of the servo level gauge, which presents the high and low level information to the user in a visible or perceptible manner.
 Common output devices include display, alarm and control valve. The display screen is usually used to display the high and low values of liquid level, so as to facilitate users to conduct real-time monitoring and judgment. The alarm is used to send out warning signals. When the liquid level exceeds or falls below the set threshold, it will send out sound or flash to remind the user to take measures in time. The control valve controls the liquid level by adjusting the flow and pressure of the liquid, and can automatically adjust the level to meet the needs of industrial production.
 The selection and design of output devices need to take into account the user's usage habits and needs, and match with the control system to achieve accurate measurement and reliable control of liquid level.