Carbon film resistance Gaseous hydrocarbons decompose in high temperature and vacuum, and carbon is deposited on ceramic rod or ceramic tube to form a layer of crystalline carbon film. Different resistance values can be obtained by changing the thickness of carbon film and the length of carbon film by grooving. Carbon film has low resistance cost and general performance.

The metal film resistor heats the alloy in vacuum, the alloy evaporates, and a conductive metal film is formed on the surface of the ceramic rod. The resistance value can be controlled by carving grooves and changing the thickness of the metal film. Compared with the carbon film resistance, this resistance is small in size, low in noise, good in stability, but high in cost.

The carbon resistor is made by pressing the mixture of carbon black, resin, clay, etc. and heat treatment. The resistance is represented by a color ring. This resistor has low cost, wide resistance range, but poor performance, so it is rarely used.

The wire wound resistance is made of constantan or nickel chromium alloy resistance wire wound ceramic skeleton. This resistance is divided into fixed resistance and variable resistance. It is characterized by stable operation, good heat resistance and small error range. It is suitable for high-power occasions, and the rated power is generally above 1 watt.

The resistor body of the carbon film potentiometer is made by coating carbon film on horseshoe shaped cardboard. There are three types of relations between the change of resistance value and the position of intermediate contact: linear, logarithmic and exponential. Carbon film potentiometers include large, small and micro ones, some of which are combined with switches to form potentiometers with switches.

Another straight sliding carbon film potentiometer changes the resistance value by sliding a sliding rod on the carbon film. The potentiometer is easy to adjust.