How do I choose the right thermistor?

The main function of thermistors is to be sensitive to temperature, and different resistance values are exhibited at different temperatures. Thermistors can also be used as electronic circuit components for temperature compensation in instrumentation circuits and cold junction temperature compensation for thermocouples. Taking advantage of the self-heating characteristics of the negative temperature coefficient thermistor, automatic gain control is realized, which constitutes the amplitude stabilization circuit of the RC oscillator.

When the self-heating temperature is much higher than the ambient temperature, its resistance is also related to the ambient heat dissipation conditions. Thermistors are often used to analyze flow meters, flow meters, and thermal conductivity to make special sensing elements.

It is generally used in places where temperature control is required, such as high-power electrical appliances and so on.

It is mainly used for temperature control, such as temperature measurement, high and low temperature protection, temperature probe, etc.!

Generally used as an electronic circuit annihilation component, the nanohail uses the self-heating characteristics of the thermistor to realize automatic gain control, and constitutes the amplitude stabilization circuit, delay circuit and protection circuit of the RC oscillator.

According to the materials used, they can be divided into: ceramic thermistors, glass thermistors, plastic thermistors, diamond thermistors, semiconductor single crystal thermistors, etc.

Heat-sensitive materials can generally be divided into three categories: semiconductors, metals and alloys; According to the different temperature coefficients, it is divided into positive temperature coefficient thermistors and negative temperature coefficient thermistors.

First, the working principle is different.

1. Thermistor: When the circuit is working normally, the thermistor temperature is close to room temperature, and the resistance is very small. The series connection does not impede the passage of current in the circuit.

When the circuit is overcurrent due to a fault, the temperature of the thermistor increases due to the increase in heating power. When the temperature exceeds the switching temperature, the resistance increases dramatically and the current in the loop rapidly decreases to a safe value.

2. Metal RTD: The temperature measurement principle of RTD is based on the characteristics of the resistance value of the conductor or semiconductor changing with temperature, measuring the temperature and temperature-related parameters. Thermal resistance is mostly made of pure metal materials.

Currently, platinum and copper are the most widely used materials. Now, nickel, manganese, and rhodium have been used to make RTDs. RTDs typically require a resistance signal to be transmitted via a wire to a computer control or other secondary instrument.

Second, the characteristics are different.

1. Thermistor:

1) The temperature coefficient of resistance is 10-100 times larger than that of metal, and the temperature change of 10-6C can be detected.

2) The working temperature range is wide, the normal temperature device is suitable for -55 315 degrees Celsius, the high temperature device is suitable for more than 315 degrees Celsius (currently up to 2000 degrees Celsius), and the low temperature device is suitable for -273 55 degrees Celsius.

3) Small enough to measure the temperature of voids, cavities, and blood vessels that other thermometers cannot.

4) Easy to use, the resistance value can be arbitrarily selected;

5) It is easy to process into complex shapes and can be mass-produced;

6) Good stability and strong overload capacity.

2. Metal RTD:

1) Pressure spring type temperature sensor, good vibration resistance;

2) High accuracy of temperature measurement;

3) High mechanical strength, high temperature and high pressure resistance;

4) Imported thin film resistor, stable and reliable performance.

Thermistor thermistors are exactly two things.

Thermal resistance is the heat of the resistance itself after being energized. It is mainly used for heating use, common thermal resistance electric blankets, electric water heaters, electric mosquito coils, and electric heating wires used in electric irons, which all belong to the category of thermal resistance.

A thermistor changes its resistance value depending on the temperature.

Relative to thermistors, thermal resistances.

Temperature - Resistance.

The characteristics are relatively close to linear;

A single RTD element has a wider operating range than a thermistor;

RTD. Temperature - Resistance.

There are strict. Number-quantity correspondence between different thermistor products.

The number-quantity correspondence is discrete.

The main features of thermistors are:

1. The sensitivity is high, and the temperature coefficient of resistance is more than 10 100 times greater than that of metal, and it can detect 10-6 temperature changes;

2. The working temperature range is wide, the normal temperature device is suitable for -55 315, the applicable temperature of the high temperature device is higher than 315 (the current maximum can reach 2000), and the low temperature device is suitable for -273 -55;

3. Small size, able to measure the temperature of voids, cavities and blood vessels in organisms that cannot be measured by other thermometers;

4. Easy to use, the resistance value can be arbitrarily selected;

5. Easy to process into complex shapes, can be produced in large quantities;

6) Good stability and strong overload capacity.