page_title: Resistor
section_title: Potentiometers
hierarchical_section_title: Resistor / Variable resistors / Potentiometers
caption_attribution_description: English: personal potentiometer
context_page_description: A resistor is a passive two-terminal electrical component that implements electrical resistance as a circuit element. In electronic circuits, resistors are used to reduce current flow, adjust signal levels, to divide voltages, bias active elements, and terminate transmission lines, among other uses. High-power resistors that can dissipate many watts of electrical power as heat, may be used as part of motor controls, in power distribution systems, or as test loads for generators.
  Fixed resistors have resistances that only change slightly with temperature, time or operating voltage. Variable resistors can be used to adjust circuit elements, or as sensing devices for heat, light, humidity, force, or chemical activity.
  Resistors are common elements of electrical networks and electronic circuits and are ubiquitous in electronic equipment. Practical resistors as discrete components can be composed of various compounds and forms. Resistors are also implemented within integrated circuits.
  The electrical function of a resistor is specified by its resistance: common commercial resistors are manufactured over a range of more than nine orders of magnitude.
context_section_description: A potentiometer (colloquially, pot) is a three-terminal resistor with a continuously adjustable tapping point controlled by rotation of a shaft or knob or by a linear slider.  The name potentiometer comes from its function as an adjustable voltage divider to provide a variable potential at the terminal connected to the tapping point.  Volume control in an audio device is a common application of a potentiometer.  A typical low power potentiometer (see drawing) is constructed of a flat resistance element (B) of carbon composition, metal film, or conductive plastic, with a springy phosphor bronze wiper contact (C) which moves along the surface.  An alternate construction is resistance wire wound on a form, with the wiper sliding axially along the coil.  These have lower resolution, since as the wiper moves the resistance changes in steps equal to the resistance of a single turn.
  High-resolution multiturn potentiometers are used in precision applications.  These have wire-wound resistance elements typically wound on a helical mandrel, with the wiper moving on a helical track as the control is turned, making continuous contact with the wire.   Some include a conductive-plastic resistance coating over the wire to improve resolution.  These typically offer ten turns of their shafts to cover their full range. They are usually set with dials that include a simple turns counter and a graduated dial, and can typically achieve three digit resolution.   Electronic analog computers used them in quantity for setting coefficients, and delayed-sweep oscilloscopes of recent decades included one on their panels.
caption: Typical panel mount potentiometer
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