What is the difference between thermocouple and thermistor

What are the differences between thermistor and thermocouple
1. Thermocouples are divided into eight different divisions, namely b, r, s, k, n, e, j, and t. The lowest temperature they can measure is minus 270 degrees Celsius, and the highest can reach 1800 degrees Celsius. Among them, b, r, and s belong to the platinum series thermocouples, which are also known as precious metal thermocouples because platinum is a precious metal, while the remaining ones are called cheap metal thermocouples.
2. Thermal resistors are generally made of Pt100, pt10,cu50,cu100, The temperature measurement range of platinum resistance thermometers is generally -200-800 degrees Celsius, while that of copper resistance thermometers is -40 to 140 degrees Celsius;
3. The application temperature range is different: thermal resistors are generally used below 300 degrees, while thermocouples are generally used above 300 degrees;
4. Different materials: Thermistors are generally made of pure metal resistance wires, while thermocouples are usually made of two alloys of different materials;
5. Different signals: Thermistors correspond to resistance values and measured temperatures, while thermocouples correspond to millivolt level signals and measured temperatures;
6. The wiring (compensation) methods are different: thermocouples require dedicated two-wire compensation wires to lead out signals, while thermal resistors generally require three copper wires.
The biggest difference between the selection of thermistor and thermocouple is the choice of temperature range. Thermistor is a temperature sensor used to measure low temperatures.
Generally, the measurement temperature is between -200~800 ℃, and thermocouples are temperature sensors for measuring medium and high temperatures. Generally, the measurement temperature is between 400~1800 ℃. When choosing, if the measurement temperature is around 200 ℃, a thermistor measurement should be selected. If the measurement temperature is around 600 ℃, a K-type thermocouple should be selected. If the measurement temperature is between 1200~1600 ℃, an S-type or B-type thermocouple should be selected.
Thermistors have the following characteristics compared to thermocouples:
1. At the same temperature, the output signal is larger and easier to measure.
2. Resistance measurement requires the use of an external power source.
3. The size of the temperature sensing part of the thermistor is relatively large, while the working end of the thermocouple is a small solder joint, so the reaction speed of thermistor temperature measurement is slower than that of the thermocouple;
4. Thermistors made of similar materials have lower upper temperature limits than thermocouples.