A Fundamental Overview of Resistors

Resistors are used in the manufacture of virtually every piece of electrical or electronic equipment. Any device that is powered by an Alternating Current (AC) or a Direct Current (DC) source incorporates resistors in their use. Without them, there would be no stereos, computers, mobile phones, tablets, televisions, and a wealth of other electronic technologies upon which to depend.

But What are They?

A resistor is a passive current limiting device. Current limiting in that they are used to slow or limit the amount of electrical current traveling through them just like a cyclist experiences when attempting to peddle full speed after encountering an increasingly strong headwind. In controlling the flow of current, the electrical potential (voltage) can also be managed. They are passive since no external power or other source is required for them to function properly.

There is no limit to the number that can be used in an electronic component, or how they function. They can be connected in either series or parallel. The required number and how they're connected is strictly based on the overall circuit design and its application.

Resistors are manufactured from wire coated with resistive materials and then sealed with an insulator. The type and corresponding properties of the resistive materials used determine its overall strength. There are different types of resistors, but the most common types are the carbon, metal film, which includes metal oxide and thick film, and wirewound. Selection of one type of resistor over another other depends on the application, cost, and technical specifications of the resistor itself.

Size and Color Coding

The resistors size is dependent on the need. They are available in sizes ranging from 0.01 Ohms to 10 Megaohms. However, there is a lot of flexibility in sizes that are commercially available. The external sealing material is equipped with color coded bands that designate the rating when viewed in a specific sequence. There are four band, five band, and six band color coded options. Each color band represents a numerical value, a resistance multiplier (in Ohms), and a percentage tolerance.

So whether designer, troubleshooter, or electronics hobbyist, having a basic understanding of how a resistor is used in the design of electronic and electrical equipment, can only serve to meet the objectives of the application and bring about a greater appreciation for electronic technology.