There are three types of common precision resistors: metal film resistors, wire wound resistors and block resistors.
1, metal film resistance is the most common, but better for precision metal film resistance, characterized by tiny temperature coefficient, resistance value is comparatively stable. Nevertheless, because the membrane is comparatively thin and thus relatively delicate, the helical cutting and crimping parts are susceptible to problems.
2, wire wound resistance is also very commonly used, and even once was the main resistance of high accuracy equipment. There are three kinds of resistance wire materials:
Kangtong: comparatively ancient, heat resistant but temperature coefficient is not perfect, and copper thermoelectric motive force is superior.
Manganese copper: precision manganese copper, although warm but not too high temperature but temperature coefficient is minimal, and copper thermoelectric electromotive force is small, is commonly used wire wound resistance material.
3, Evanohm (Evanohm) : This is a nickel-chromium aluminum copper alloy, can also be referred to as nickel-chromium resistance alloy, the temperature coefficient is the smallest, the material is relatively hard, the welding performance is not very good.
Block resistance, also called foil resistance.