Of all the commonly used temperature sensing devices, thermistors are the number one choice when sensitivity is needed. Compared to the three major categories of sensors, thermistors are known to exhibit, by far, the most significant parameters change with temperature.
To get most of the sensors, you must make certain practical precautions. The same precautions apply to thermocouples as well. Below, we want to take the time to cover the basics of the most important precautions that should be observed.
Self-heating: Thermistors are not self-powered, which means a current must pass through the device to provide measurable voltage. The current causes Joule heating within the sensor. Self-heating will appear as a measurement error. You must make sure to pay attention to the magnitude of measurements of the current supplied by the ohmmeter.
To reduce these errors, consider using a minimum ohms measurement current that still gives the resolution required. Use the largest thermistor to get a good response time. You must also consider the compromises being made.
Construction: as a result of construction, the thermistor is a bit more fragile when compared to a thermocouple. Precautions must be taken to protect devices.
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