If you want a reliable temperature measurements, first you need to select the correct temperature meter, that is, the temperature sensor. Wherein thermocouples, thermistors, platinum resistance (RTD) and temperature tests are the most commonly used IC temperature sensor.
The following is a thermistor and thermocouple meter features introduced two temperatures.
1, thermocouple
Thermocouple temperature measurement is the most commonly used temperature sensor. Its main benefit is to adapt to a wide temperature range and atmospheric environment,

Temperature sensor (5)
And strong, low price, no power, but also the cheapest. Thermocouple consists of two different metal wires connected at one end (the metal A and metal B) constitute, when heated at one end of a thermocouple, thermocouple circuits have potential difference. Available potential difference measurements to calculate the temperature.
However, between the non-linear relationship between the voltage and temperature, since the temperature is non-linear relationship between voltage and temperature, and therefore the need for the reference temperature (Tref) for the second measurement, and the use of the test equipment software or hardware in the processing within the instrument voltage - temperature conversion to ultimately, thermocouple temperature (Tx). Agilent34970A and 34980A data acquisition system has a built-in measuring the computing power.
In short, the thermocouple is the simplest and most common temperature sensors, but not suitable for thermocouple measurement and application of precision.
2, the thermistor
Thermistor is a semiconductor material, mostly negative temperature coefficient, ie the resistance decreases with increasing temperature.

A temperature sensor (6)
Temperature changes can cause large changes in resistance, and therefore it is the most sensitive temperature sensor. But poor linearity of the thermistor, and a great relationship with the production process. Manufacturers to not standardized thermistor curves.
Thermistor volume is very small, in response to temperature changes too fast. But thermistor requires a current source, the small size also makes it extremely sensitive to self-heating errors.
Thermistor measurements in two lines is the absolute temperature, better precision, but it more expensive than thermocouples, can be measured temperature range is less than a thermocouple. A common thermistor resistance at 25 ℃ of 5kΩ, per 1 ℃ temperature changes caused by the change in resistance of 200Ω. Note 10Ω lead resistance caused only negligible 0.05 ℃ error. It is ideal for control applications require fast and sensitive current temperature measurement. Size small space requirements for applications is beneficial, but must be taken to prevent self-heating errors.
Thermistor as well as its own measurement techniques. Thermistor small is an advantage, it can be stabilized soon, it will not cause the heat load. However, very strong and therefore, a large current will cause self-heating. Since the thermistor is a resistive device, any current source will be in on it because of power caused by heat. Power is equal to the square of the current resistance area. Therefore, to use small current source. If the thermistor is exposed to high heat, and it will lead to permanent damage.
Through the introduction of two temperature instruments, we want to work and study help.