What Is Potentiometer And How It Works - Spectra Symbol

By Author: Daniel Marriott
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This device adjusts the voltage or current flow in a circuit. One device frequently used as a voltage-dividing component is the potentiometer, which is a resistor with a movable element positioned by a manual knob or lever which are used to control such parameters as volume, treble, bass, brightness and contrast. Unlike with a normal resistor, the resistance of a potentiometer can be changed, usually either by turning a knob or adjusting a slider. Potentiometers are used to control a wide variety of different circuits including thermostats, dimmer switches and even joysticks.

Potentiometers work by having a resistive element inside. Both end terminals are attached to it, and do not move. The symbol for a potentiometer is the same one as a resistor, save for an arrow in the middle. In a circuit where they are used strictly as variable resistors, only two terminals are wired to the other components. All three terminals are wired separately when they function as voltage dividers. Light dimmers in houses and volume controls on electronics are two common applications. Others include switches and position sensors. A potentiometer ...
... generally has 3 terminals. 2 of the terminals are connected (internally) to the opposite ends of a resistive element. The 3rd terminal is called the wiper. It is generally located in-between the other 2 terminals. The wiper is a contact (actually, generally several very small contacts) that makes contact along the resistive element.

In order to adjust the resistance of the potentiometer and therefore the current flow, a knob of some sort is used to move the third terminal along the resistive strip. When used to regulate current, the potentiometer is limited by the maximum resistance of the strip. The change in the resistance is either linear, like a dimmer for light, or logarithmic, like volume controls, which is used because the human ear does not respond linearly to loudness - it responds to the logarithm (curve) of loudness. This is accomplished by slowly increasing the speed that the wiper traverses the resistive material.

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