The Different Types of Resistors
Resistors ( R ), are the most fundamental and commonly used of all the electronic components, to the point where they are almost taken for granted. There are many different Types of Resistors available to the electronics constructor, from very small surface mount chip resistors up to large wire wound power resistors.
The principal job of a resistor within an electrical or electronic circuit is to "resist" (hence the name resistor), regulate or to set the flow of electrons (current) through them by using the type of conductive material from which they are composed. Resistors can also be connected together in various series and parallel combinations to form resistor networks which can act as voltage droppers, voltage dividers or current limiters within a circuit.
There are many thousands of different Types of Resistors and are produced in a variety of forms because their particular characteristics and accuracy suit certain areas of application, such as High Stability, High Voltage, High Current etc, or are used as general purpose resistors where their characteristics are less of a problem. Some of the common characteristics associated with the humble resistor are; Temperature Coefficient, Voltage Coefficient, Noise, Frequency Response, Power as well as Temperature Rating, Physical Size and Reliability.
Standard Resistor Symbols
The symbol used in schematic and electrical drawings for a Resistor can either be a "zig-zag" type line or a rectangular box.
Composition Type Resistors
Carbon Resistors are the most common type of Composition Resistors. Carbon resistors are a cheap general purpose resistor used in electrical and electronic circuits. Their resistive element is manufactured from a mixture of finely ground carbon dust or graphite (similar to pencil lead) and a non-conducting ceramic (clay) powder to bind it all together.
Film Type Resistors
The generic term "Film Resistor" consist of Metal Film, Carbon Film and Metal Oxide Film resistor types, which are generally made by depositing pure metals, such as nickel, or an oxide film, such as tin-oxide, onto an insulating ceramic rod or substrate.
Wire wound Type Resistors
Another type of wire wound resistor is the Power Wire wound Resistor. These are high temperature, high power non-inductive resistor types generally coated with a vitreous or glass epoxy enamel for use in resistance banks or DC motor/servo control and dynamic braking applications. They can even be used as space or cabinet heaters.
