Water Temperature Measurement Method Based on Square-Wave Signal Generator

Abstract Water temperature measurement is widely used and plays an important role in fishery breeding, agricultural irrigation, temperature control of household water heater and other aspects. People have a huge demand for water temperature measurement devices. The performance of the existing device is greatly affected by the environment and often requires manual intervention. The square-wave signal generator has simple structure, stable output, low energy consumption, easy operation and low price. The water temperature measurement method based on the square-wave signal generator can expand the application range of the square-wave signal generator, promote the convenience of measurement work and then improve the measurement sensitivity. Based on operational amplifier, Schmitt-Trigger Inverter and 555 Timer, the output frequency of the circuit changes according to the change of the overall resistance value of the circuit. A waterproof thermistor is added to the circuit and placed in water. The water temperature would change the resistance value of the overall circuit by changing the resistance value of the thermistor. Therefore, different output frequencies of the measuring circuit reflect different water temperatures. The working principles of the above three measuring circuits are specifically described, and their measuring characteristics are compared. It can be seen that the circuit based on 555 Timer has stable measuring performance and high sensitivity, which can be widely applied to the needs of water temperature measurement in production and life. What’s more, it provides a new idea for water temperature measurement.