Resistors are components, which resist or limit the flow of electric current in a circuit. They are designed to protect a circuit. The unit of measure is the ohm. An additional important characteristic is the wattage rating which indicates the power needed for the resistor to function.
Resistors are rated with a tolerance, which indicates the upper and lower limits of variation from a components nominal value i.e., an allowable deviation. These ratings are usually indicated by a % value. The lower the % ratings are on a part the better the tolerance.
Most film resistors are identified by a system of different color bands indicating the ohms, tolerance and a failure rate when applicable.
The wattage rating is determined by size.
Resistors are produced in many styles and can be composed of a variety of different materials, each of which provides its unique resistance properties.
|Adjustable Wireound||MELF||Thick Film Surface Mount Chip|
|Aluminum Wirewound||Metal Film||Thin Film Surface Mount Chip|
(Silicon Vitreous Enamel)
|Metal Oxide||Tubular Wirewound|
|Carbon Composition||Potentiometers||Variable Cermet and Wirewound|
|Carbon Film Ceramic Cased
|Allen Bradley||Futaba||Mepco||S.E.I (Stackpole)|
(formerly Beckman Industrial)
|Huntington Electric||Milwaukee Resistor||Spectrol|