Below we will discuss the two common pressure instrument applications: thermal resistors and temperature sensors:

1. Thermistor Thermistor is a common temperature sensor in temperature detection. Its main advantages are wide temperature range and adaptability to various ambient air. It is also sturdy, low price, and does not require a power supply, so it is also cost-effective. Thermistor consists of two different metal wires (metal A and metal B) connected at one end. When one end of the thermistor is heated, there will be a potential difference in the thermistor circuit.

The temperature can be calculated using the accurately measured potential difference. However, the operating voltage and temperature are discrete relationships. Since the operating voltage and temperature are discrete relationships, it is necessary to make a second accurate measurement of the reference temperature (Tref), and use the test equipment software or hardware to solve the operating voltage-temperature conversion inside the instrument to obtain the thermocouple temperature (Tx). To put it simply, thermal resistors are simple and versatile temperature sensors, but they are not suitable for high-precision measurement and application.

2. Temperature sensor The temperature sensor is a semiconductor device, most of which have a negative temperature coefficient, that is, the resistance decreases as the temperature increases. Temperature changes will cause large changes in resistance, so it is a flexible temperature sensor. However, the temperature sensor has linear deviation and is closely related to the production process. Manufacturers cannot provide standardized temperature sensor curves.

The temperature sensor is very small and responds quickly to temperature changes. However, the temperature sensor requires a current source, and its small size also makes it extremely sensitive to self-heating deviations.

The temperature sensor accurately measures the relative temperature in two channels, and has good precision, but its constant pressure is more expensive than that of thermocouples, and its measurable temperature range is also lower than that of thermocouples. A common temperature sensor has a resistance value of 8kΩ at 25℃, and each 1℃ temperature change results in a 200Ω resistor change.

Note that the 10Ω lead resistor only causes a negligible 0.05°C error. It is ideal for current control applications where fast and flexible temperature sensing is required.