Temperature sensor: principle of operation and scope

In electrical circuits of control, protection or control, a temperature sensor is widely used . It is necessary for adjusting the thermal modes when the most different equipment is in operation. Such devices are widely used in household appliances: washing machines, televisions, computers, etc. Using a temperature sensor allows you to avoid many accidents and save expensive equipment in the workplace and at home.

These instruments convert the measured object temperature into an analog or relay signal, which is understandable for receiving equipment. They differ in the way they convert the heat signal and there are several types:

• It has long been known that when the temperature changes, the internal resistance of materials changes. On the basis of this, thermoresistive thermal sensors were created. The temperature sensor of this type has small dimensions and good performance characteristics. It is in good agreement with the work in low-current circuits with electronic circuits that isolate any change in resistance and use the received signal for further conversion. The disadvantages include the nonlinearity of the characteristic, which leads to the complication of the schemes for changing the received signal.
• Semiconductor thermal sensors work on the same principle, but they are much more sensitive than thermoresistive ones. They have a linear characteristic, they are easy to make at home. The shortcomings include a small range of measured temperature (-55 - +155).
• Thermoelectric converters are widely used in production, for example, in electric arc furnaces to control the process. Thermocouples of platinum or tungsten groups have a wide temperature range of measurement. They can work normally under conditions that exceed the melting point of many metals. A temperature sensor of this type can be found in everyday life, it can be used to control the temperature in the sauna.
• For remote temperature measurement, special devices are used that detect thermal waves emanating from heated bodies. A temperature sensor of this type is called a pyrometer. The disadvantages of such devices include frequent distortion of the temperature field and a decrease in the stability of the device itself.
• Acoustic sensors are used for measurements in gas and other media. They can be useful where contact measurement methods are not possible. The principle of their operation is based on a change in the speed of propagation of acoustic waves in differently heated media. Temperature sensors of this type have a large error. Often repeated measurements are required to refine the measurement results.

All of the above temperature sensors are widely used in the design and creation of electronic devices of varying degrees of complexity. Without them, the functioning of most of the schemes becomes impossible, and much depends on their stable work. When designing the most critical nodes on the basis of these elements, duplication of the readings of various sensors is often used.