What is a varistor?
Varistor is a voltage-limiting protective electronic component with nonlinear volt-ampere characteristics. Within a certain voltage range, its resistance value decreases sharply with the increase of voltage. It plays the role of suppressing transient overvoltage and lightning protection in the circuit. When the circuit is overvoltage, it performs voltage clamping, absorbs excess current to protect other electronic devices in the circuit, and prevents damage caused by electrostatic discharge, surge and other transient currents. cause damage to electronic devices.
Varistors have the advantages of fast response speed, various surge withstand capabilities, large flow capacity, small normal leakage current, and low residual voltage level, etc. These advantages are widely used in the protection of semiconductor electronic components such as transistors, diodes, and ICs; communications, measurement and Electric control and other electronic equipment, consumer electronics, industrial electronics, etc.
It is precisely because of these advantages of varistors that many electronic products can operate normally and work for a long time after using varistors. However, some varistors used in electronic products not only fail to protect them, but also burst, causing electronic products to malfunction. For example, three non-varistors.
We often hear three-no products in our daily life. Three-no products generally refer to products without production date, quality certificate and no varistor manufacturer. Some unscrupulous merchants sell Sanwu products at low prices, and many people buy Sanwu products because they are greedy for petty gains. As a result, all the Sanwu products they buy have problems. Therefore, be careful not to be greedy and cheap to buy three-no products. Before buying items, you must check whether there are production dates, quality certificates, and manufacturers of varistors.
The same is true for varistors. Good varistors must have production qualifications, production dates and production inspection reports. Although the price is a bit more expensive, the quality and quality of such varistors are guaranteed. You can find sellers or varistor manufacturers to let them solve after-sales problems.
Varistors without production qualifications, production dates, and production inspection reports are much cheaper, but the quality is worrying and cannot be guaranteed. If used in a circuit, the varistor may burst, or the circuit may burn down, causing a fire.
You get what you pay for, and the use of inferior varistors is not only easy to cause damage to electrical appliances, but also easily endangers personal safety. When using varistors, you must choose a varistor manufacturer with a brand, production qualification, and after-sales service.
What is a thermistor
A thermistor is a temperature-sensitive resistor whose resistance value changes with the surrounding temperature. Most thermistors are made of single crystal and polycrystalline semiconductor materials and belong to semiconductor components.
There are many types of thermistors. According to the temperature coefficient, thermistors can be divided into two types of thermistors, positive temperature coefficient and negative temperature coefficient. The positive temperature coefficient thermistor is referred to as PTC thermistor. Within a certain temperature range, its resistance value increases with the rise of temperature; the negative temperature coefficient thermistor is referred to as NTC thermistor. Within a certain temperature range, its resistance value increases. Decreases with increasing temperature.
Because the thermistor has high sensitivity to temperature, low thermal inertia, and can work for a long time, it is used in applications such as temperature detection, circuit switching, temperature control, and temperature compensation, such as cooking appliances, air conditioning equipment, and hot water. Water supply equipment, printers, car engines, etc. Thermistors are like clothes, with different sizes, volumes and various parameters, and the appropriate thermistor will be selected according to the operating temperature range and workplace. Once an inappropriate thermistor is selected, the result will be Either it can’t be used, or it can damage the circuit and electronic equipment. Therefore, if you want to choose a suitable thermistor, you should pay attention to these points.
Different thermistors have different operating temperature ranges. Normal temperature devices are suitable for -55°C to 315°C, high temperature devices are suitable for temperatures higher than 315°C, and low temperature devices are suitable for -273°C to -55°C. Choose according to the operating temperature range suitable thermistor.
Use different workplaces
Different types of thermistors have different working occasions. PTC thermistors are generally used in refrigerator compressor starting circuits, color picture tube degaussing circuits, motor overcurrent and overheating protection circuits, current limiting circuits and constant temperature electric heating circuits; NTC thermistors It is used for microwave power measurement, temperature inspection, temperature compensation, temperature control and voltage stabilization in various electronic products.
There are many types of thermistors, so pay attention when choosing the type of thermistor and choose the right thermistor. If you don’t know how to choose a thermistor, you can consult engineers or staff in related industries, and they will provide suitable solutions according to your needs.
