Resistance is one of the most widely used circuit components, accounting for more than 30% of the total number of components in electronic equipment, and its quality has a great impact on the stability of the circuit. It is mainly used to stabilize and regulate current and voltage in circuits, and also used as a shunt, voltage divider and load.
Resistance is often denoted by the letter "R" in a circuit. Common resistors are fixed resistance and variable resistance, with higher and higher integration, now common and patch resistance. According to different production materials and processes, resistors can be divided into film resistance, (carbon film resistance, metal film resistance, synthetic film resistance, oxide film resistance), solid resistance (organic solid resistance and inorganic solid resistance), special resistance, (photosensitive resistance, thermistor, pressure sensitive resistance, insurance resistance) and so on.
Photosensitive resistance in some widely used with the infrared camera, thermistors are applied on the hard disk video recorder power equipment, insurance resistor in a circuit plays a dual role of fuse and resistance, in the security of electronic equipment power supply output circuit and the output of the secondary power supply is widely used in general with low resistance, low power is, Its function is in the circuit load short circuit fault, when there is overcurrent, the temperature of the insurance resistance rises instantly, resistance layer is heated and fused, play the role of insurance, so as to improve the safety of the whole machine.