Temperature Sensor Comparison
With all of the different ways to measure temperature it can be difficult to decide which sensor will work best in a given situation.
In this lesson we will compare the pros and cons of the different types of temperature sensors and the applications each is best suited to.
Thermistors
Thermistors are temperature-sensitive resistors.
They have a wider variation in their properties than the other kinds of temperature sensors which makes them useful in a range of everyday devices.
Engine and transmission temperature monitoring, refrigerators, medical thermometers, microwaves, and computers are all examples of applications where thermistors may be used.
A thermistor's operating range is usually within the range of temperatures that humans can directly interact with, about -90˚C to 130˚C.
For a more in-depth look at how thermistors work, check out the thermistors lesson here.
The advantages of thermistors include:
A high level of accuracy within their operating range.
Fast response times to changes in temperature.
Can be ruggedized so they are not affected by shocks or vibrations.
Low cost.
There are, of course, disadvantages to thermistors.
These include:
Their narrow operating range.
+/- 10˚C of their preset temperature point.The risk of self-heating errors. As a type of electrical resistor, thermistors use current to operate. Too much current will heat the thermistor and throw off the thermistor's reading.
Thermocouples
Thermocouples are the go-to choice for heavy duty temperature sensing.
They can operate in very high temperature environments and are resistant to being affected by vibration.
Thermocouples are commonly found in heavy industry applications such as metal smelting, power generation, and chemical production.
For a more in-depth look at how thermocouples work, check out the thermocouples lesson here.
The advantages of thermocouples include:
Rugged.
Inexpensive.
Can measure high temperatures.
Not susceptible to self-heating errors.
Do not need an excitation circuit - they are self-powered.
The disadvantages of thermocouples include:
Less accurate than other options.
Low stability. Accuracy tends to degrade over time.
Expensive extension leads.
Cold-junction compensation.
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