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Construction Standard Variable Resistor Photograph © Rapid Electronics Variable resistors consist of a resistance   track   with connections at both ends and a   wiper   which moves along the track as you turn the spindle. The track may be made from carbon, cermet (ceramic and metal mixture) or a coil of wire (for low resistances). The track is usually rotary but straight track versions, usually called sliders, are also available. Variable resistors may be used as a rheostat with  two  connections (the wiper and just one end of the track) or as a potentiometer with all  three  connections in use. Miniature versions called presets are made for setting up circuits which will not require further adjustment. Variable resistors are often called  potentiometers  in books and catalogues. They are specified by their maximum resistance, linear or logarithmic track, and their physical size. The standard spindle d...

The Different Types of Resistor 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 Resistor  available for the electronics constructor to choose from, from very small surface mount chip resistors up to large wirewound 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. Resi stors 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. A Typical Resistor Resistors are “ Passive Devices “, that is they contain no source of power or amplification but only attenuate or reduce the voltage or c...