Linear potentiometers produce a resistance output that varies according to the displacement or position of a slider or wiper.  They are variable resistors with three leads. Two leads connect to the ends of the resistor, so the resistance between them is fixed. The third lead connects to a slider that travels along the resistor varying the resistance between it and the other two connections. The resistance element is excited by either DC or AC voltage. This video discusses potentiometers in general and compares linear and logarithmic tapers.

 Video Credit: Planet Z

Types of Linear Potentiometers

"Linear" can refer to the motion of the slider. Such a device is also known as a slide potentiometer. By contrast, a rotary potentiometer slider twists.

Linear/Slide

"Linear" can refer to the taper (law)-how the output voltage varies with the motion of the slider. A linear taper means that resistance increases in direct proportion to the distance traveled along the resistive element. This contrasts with a change in resistance via a logarithmic scale (a log or audio taper).

Specifications and Features

Sensors vary in dimension (length, width, height, diameter, weight).

Electrical working range is the length of the stroke (e.g., less than 1" to 29" or more).

Total resistancevaries (e.g., less than 2 to more than 74 kiloohms).

Minimum accuracy ranges (better than 15% to better than 0.02%).

Electrical output signals can be analog (current, voltage, or frequency), digital (serial, parallel, or other), an alarm, or a change in state of switches.Sliders can be housed in rectangular or cylindrical body types, sealed against environmental contamination, and/or free to rotate.

Resistive element types can be carbon (inexpensive), cermet (relatively limited life), conductive plastic (long life), wire wound (current drawn during use).Devices can tolerate certain operating temperatures (e.g., -13 to 165 F).

Packaging can be a raw sensor element or a housed transducer. Self-contained instruments or meters display output at or near the device. Gauges/indicators have an analog display and no electronic output.

Applications

Linear potentiometers are used in test/lab, marine, medical, and farm equipment, as well as heavy industry, industrial processing, and robotics.

References

Basic Car Audio Electronics - Potentiometers

Image credits:

PMC Engineering LLC