Resistors, I believe everyone is familiar with them. Basically, there is no circuit board without resistors. The most commonly used device on any circuit board is resistors, and various resistors achieve different functions. Some use the thermal effect of resistors, some use the current limiting characteristics of resistors, and some use impedance matching of resistors, etc.
Diverse resistance categories
There are many classification methods for resistors, and they can be fully classified according to different materials, structures, uses, and even lead electrodes. A more common classification is to classify resistors into three categories based on whether their resistance values are adjustable: fixed resistors, variable resistors, and semiconductor sensitive resistors.
Variable resistors refer to resistance values that can be manually adjusted continuously within a certain range. Currently, the common types are adjustable wire wound resistors and sliding wire resistors, which are mainly used to meet the various needs of small signal circuits, complete some functions of adjusting current and voltage, and control signals. Furthermore, variable resistors are also used to achieve the function of adjusting sound and frequency.
There are many types of subdivisions under fixed resistors, including wire wound resistors, film resistors, solid core resistors, and metallic glass glaze resistors, all of which have a fixed resistance value once they are made. At present, there are two types of resistors with higher usage: membrane resistors and wire wound resistors. There are many sub categories of resistors under these two types of resistors.
Popular resistor applications
The characteristics of membrane resistors vary depending on the materials used, such as the resistance of carbon films, which have a wide range of resistance values and are quite stable. Carbon film resistors with high cost-effectiveness are applied in many electronic devices, such as radios, televisions, and other household devices. Compared to carbon film resistors, metal film resistors have better heat resistance and can adapt to more working conditions. They have many applications in devices that require high resistance performance, such as communication equipment, radar equipment, and various electronic instruments, and their costs are slightly higher than carbon film resistors.
Solid core resistors use organic or inorganic synthetic materials with high mechanical strength and strong overload capacity. At present, organic solid core resistors are more commonly used in situations with high precision requirements.
Non adjustable wire wound resistors are also a widely used type of fixed resistor. Overall, wire wound resistors have high power, low noise, and can operate at very high temperatures. The selection of materials for the insulation, wire, and packaging parts all have a significant impact on the performance of the formed resistor. The reliability and stability are related to the insulation and packaging materials. The different resistance wires determine the temperature drift and resistance value of the resistor, as well as the short-term overload capacity and long-term stability of the resistor. Wire wound resistors are inevitably not suitable for high-frequency scenarios due to their wire wound structure.
Semiconductor sensitive resistors are familiar to us as varistors, thermistors, photosensitive resistors, and so on. This type of resistor plays a very important role in the corresponding field.
For example, as users pay more and more attention to device safety, the fault safety function of devices is becoming more and more popular, and the types of varistors on the market have begun to increase in recent years. Varistors are often used as core voltage limiting devices, and the larger the flow rate, the greater the surge current they can withstand. Varistors act as suppressors to protect equipment and circuits from transient abnormal voltages such as ESD electrostatic discharge or lightning surges. In small electronic devices, the current ultra small surface mount multilayer varistors are very popular.
Thermistors are the basic devices for various temperature sensors to achieve sensing functions. Compared to traditional thermistors, chip thermistors can achieve more stable thermal coupling with power modules, achieve ultra fast response, and achieve high-precision temperature measurement and control. In terms of circuit protection and control, thermistors also have many applications, used to suppress startup surges and ensure that electronic devices are not damaged.