Types of Resistors by Composition
There are many different types of resistors with various composition, characteristics, and functions. Some resistors are composed of carbon, while others are composed of metal-film. We’ll go over three main types of resistors based on their composition: carbon-composition resistors, carbon-film resistors, and metal-film resistors.
Carbon-Composition Resistors: Carbon-composition resistors are resistors that are made of finely divided carbon mixed with a powdered insulating material as a binder in the proportions need for the desired R value. More carbon means less resistance, while more binder means more resistance. Carbon-composition resistors often are cylindrical with a brown body. The resistance values of carbon-composition resistors are commonly vary from 1Ω to 20MΩ, and the power rating is generally 0.1W, 0.125W, 0.25W, 0.5W, 1W, or 2W.
Carbon-Film Resistors: A carbon-film resistor is a resistor in which a thin film of carbon is deposited onto an insulated substrate and then cut into a spiral body. More carbon means less resistance, while more insulating material means more resistance. Carbon-film resistors have the following advantages: lower and tighter tolerances, less sensitivity to temperature changes and aging, and less noise generated internally.
Metal-Film Resistors: A metal-film resistor is a resistor in which a thin film of metal is sprayed onto a ceramic substrate and then cut into a spiral body. Unlike the above two resistors, the resistance value of a metal-film resistors are complicated which is determined by the length, thickness, and width of the metal spiral simultaneously. Compared three resistors, metal-film resistors perform the best, while carbon-composition resistors the last.