What is armistor?The thermal resistance of the term comes from "heat" and "resistance". Thermal resistance is a resistance that depends on the temperature; it is a resistor thermometer. They are made of metal oxides. These metal oxides are shaped into beads, discs or cylindrical shapes, and then closed with epoxy resin or glass.
The thermistor does not work well at extreme temperature, but they are very suitable for measuring temperature at a certain point; when they are used within a limited temperature range, that is, when they are used within 50 ° C of the target temperature, they It is precise; this range depends on the basic resistance.
Thermistor is easy to use, relatively cheap, and durable. They are usually used in digital temperature meters, car measurement of oil and cooling agents, and household appliances, such as ovens and refrigerators, are the first choice applications that need to be heated or cooling protection circuits safely.
This thermistor is built into more complex applications, such as laser stable detectors, optical blocks, and charge coupling equipment. For example, the 10 kΩ thermistor is a standard resistance built -in in laser packaging.
How does the thermal resistance work work?
There are two types of thermistor-the most commonly used is the negative temperature coefficient (NTC) thermistor. The resistance of NTC decreases as the temperature rises, and vice versa. For the thermistor of the positive temperature coefficient, the resistance increases as the temperature rises, and vice versa; it is usually used as a fuse.
The type of material used in thermal resistance determines the degree of resistance with temperature changes. The thermistor is non -linear, that is, the connection between the resistance and the temperature will not form a straight line, which will form a curve on the figure; Essence
How to convert the change of resistance into measured data?
The change of the resistance needs to be converted to temperature, and then generates measured data.
The comparison of thermistor and other sensors
Other types of temperature sensors used include resistance temperature detectors (RTD) and integrated circuits. Each type of sensor has its advantages and disadvantages, and the application will determine the best instrument use.
1. Thermistor
advantage:
durable
sensitive
Small scale
The price is relatively cheap
The most suitable measuring single -point temperature
shortcoming:
Curve output
The temperature range is limited
2. Resistance temperature detector
advantage:
Very accurate
Linear output
Wide temperature range
shortcoming:
slow response
Costly
Types of thermistor resistance:
From chip to rod -shaped, there are many shapes for surface installation or embedding.
The shape is determined by the monitored substance type, such as solid, liquid or gas. They can be packaged in the resin/glass, baked on the phenolic resin, or color according to the application. For example, the thermistor chip is installed on the circuit board, and the bead -shaped thermistor can be embedded in the device. Regardless of the application, the monitoring of the largest surface contact device, and using the connection of heat conduction (non -conductive) paste or epoxy glue is ideal.
