Fixed Resistors and Their Common Types

When designing an electronic device or system, ensuring that proper resistance is in place is paramount to safe operation. Resistance refers to a material’s ability to impede the flow of electric current, allowing for the limitation of electrical flow in order to protect sensitive components and those that are operating the system. Resistors are the component or device that is implemented to oppose electric current, and there are various types that are commonly used across different electronic applications depending on the amount of electricity present and the need for impeding electricity.

Resistors often come in two forms, those being linear and non-linear resistors. Linear resistors are those that adjust under voltage and temperatures, allowing for a proportional current value to the applied voltage. In general, the two main types of linear resistors are fixed resistors and variable resistors. Fixed resistors are the most widely used resistor type, and they feature a specific value that cannot be changed. Across applications, the most common types  of fixed resistors include the carbon composition resistor, wire wound resistor, thin film resistor, and thick film resistor.

The carbon composition resistor is a fixed resistor that may be produced from a mixture of granulated or powdered carbon, a resin binder, or an insulation filler. To dictate the value of resistance that carbon composition resistors provide, the ratio of insulation material may be adjusted. Additionally, such resistors will usually feature color coded lines on the surface of the component to denote the value of resistance. Two conductor wires also protrude from each side of the resistors, allowing for them to be soldered onto a circuit for use. In general, the carbon composition resistor will range in value of 1 ohm to 25 mega ohms.

The wire wound resistor lives up to its name, consisting of an insulated core that is covered with a resistive wire that is wound around it. Typically, the wire is constructed from metals such as tungsten, nichrome, nickel, manganin, or nickel chromium alloy, and the core is made from an insulating material such as porcelain or ceramic clay. Wire wound resistors can be utilized for high rated applications, and wire wound resistors range in a resistance value of 0.1 ohms to 100k ohms. As compared to the carbon composition resistor, the wire wound resistor operates with less noise and can handle overload conditions, thus they are useful for applications in which there is a need for high sensitivity and balanced current control.

The thin film resistor is a type that is produced from a high grid ceramic rod and a resistive substance, and a conductive material is then overlaid upon it. The thin film resistor comes in two types, those being carbon film resistors and metal film resistors. The carbon film resistor is composed of a rod made from a high grade ceramic material, and a thin carbon layer is wrapped around it. With their quiet operation, such resistors are typically used in a wide variety of electronic circuits. The metal film resistor type is similar in construction to the carbon film resistor, though a metal is used for the film. Metal film resistors are quite cheap, and they are reliable during their operation.

1. mark bogart
2. Posted on October 22, 2020
electronics

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