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Know about Various Types of Temperature Sensors


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Temperature sensors are devices that collect thermal data and converts it into information that we can understand. They’re used in many different applications from HV and AC systems, food processing units, medical devices, and automotive devices. Resultantly, there are many different types of temperature sensors.

Thermocouples, or TC, are the most common temperature sensor. They’re low-cost, rugged, self-powered, and have long-distance capabilities. Using the thermo-electric effect, thermocouples use two different metals to produce a voltage which causes a thermal difference. When temperature goes up, the voltage output also increases. Though the relationship is proportional, it is nonlinear. 

Resistor temperature detectors, or RTDs, are one of the most accurate sensors with resistance proportional to the temperature and a temperature range of -270 C to 850 C. Using the two, three, or four-wired method, a current is forced through the RTD which measures the resulting voltage. RTDs are the most accurate but can have errors as a result of the current producing extraneous heat. Fortunately, the heat is easy to calculate out.

Thermistors are relatively inexpensive, adaptable, and easy to use. Similar to RTDs, they change resistance when the temperature changes, however they have an inverse relationship, so when one increases, the other decreases.

Thermistors are also more sensitive than RTDs. Thermometers contain a liquid, mercury or alcohol, that changes in volume when the temperature changes. The relationship between the temperature and the change in volume is linearly proportional, so the temperature can be read on a scale on the thermometer in Kelvin, Fahrenheit, and Celsius.  

Semiconductor sensors have high linearity and high accuracy over a range of 55 C to 150 C. They come in various different types, such as current output temperature sensor, voltage output temperature sensor, and digital output temperature sensor.

IR sensors are non-contact sensors that can measure temperature by simply detecting IR radiation. If you hold out an IR sensor in front of your cup of coffee, not letting the two touch, the IR sensor can still detect the temperature from the radiation alone.

With so many different temperature sensors, how accurate and powerful it is depends on how much you are willing to spend. At ASAP Semiconductor, we have everything you’d need, from thermocouples and thermistors, to thermometers and handheld temperature meters. Check out our website, www.asapsemi.com, to request a quote.


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