What is a Potentiometer?

A potentiometer is a three-terminal resistor with a sliding or rotating contact that forms an adjustable voltage divider. It is one of the most widely used electronic components in the world, found in everything from audio volume controls and lighting dimmers to industrial automation systems, automotive sensors and medical instruments.

At its core, a potentiometer consists of a resistive element with a movable wiper that slides along its surface. When a voltage is applied across the two outer terminals, the wiper picks off a fraction of that voltage that is proportional to its position. This single, simple principle makes the potentiometer the workhorse of manual and semi-automatic adjustment in virtually every electronics industry.

Potentiometers are used in two fundamental ways. The first is as a variable resistor (rheostat), where only two terminals are used and the component controls current flow. The second — and more common — is as a voltage divider, where all three terminals are connected and the output is a variable voltage. Understanding which mode your circuit needs is the first step in selecting the right component.

How a Potentiometer Works

Inside a rotary potentiometer, a resistive track is arranged in a circular arc and a wiper rotates with the shaft, sweeping across the track. In a sliding potentiometer, the track is straight and the wiper moves linearly. Either way, the electrical behaviour is identical: the resistance between the wiper and each end terminal changes continuously with position.

The relationship between wiper position and resistance is described by the taper of the element. A linear taper (designated "B" in most manufacturers' codes) produces resistance that changes evenly with shaft angle, which is ideal for voltage dividers, sensor feedback and equalisation circuits. An audio or logarithmic taper (designated "A") compresses resistance changes at one end of travel and expands them at the other, matching the human ear's logarithmic response to loudness. Getting the taper right matters — using a linear pot in an audio volume control produces an uncomfortable jump in volume near the low end of rotation.

Types of Potentiometers We Manufacture

Jason Electronics manufactures four main element technologies, each suited to different applications and performance requirements.

Carbon Film Potentiometers

Carbon film elements are the most economical option and are produced by depositing a carbon-based resistive layer onto an insulating substrate. They offer good electrical performance at a low cost, making them the default choice for consumer audio equipment, home appliances and general-purpose controls. Their main limitations are higher temperature coefficient and lower long-term stability compared with premium element types.

Cermet Potentiometers

Cermet (ceramic-metal) elements are made by firing a metal-glass composite onto a ceramic substrate. They deliver excellent stability, low noise and a wide operating temperature range, which is why they dominate industrial controls, power supplies and precision trimming applications. Cermet potentiometers hold their set value well over time and temperature, a critical property in calibration circuits.

Wirewound Potentiometers

Wirewound elements use a precision resistance wire wound around a former. They offer the tightest tolerance, lowest temperature coefficient and highest power handling of the common element types. Wirewound potentiometers are the standard choice for high-power applications, laboratory instruments and heavy industrial equipment, but they have limited resolution — the wiper moves in discrete steps as it crosses individual wire turns — and they are not suitable for high-frequency circuits because of their inherent inductance.

Conductive Plastic Potentiometers

Conductive plastic elements combine a polymer binder with conductive particles, producing a smooth, low-noise track with very long mechanical life. They are the preferred element for servo feedback, robotic positioning, and any application that demands millions of rotations without degradation. Conductive plastic potentiometers deliver infinite resolution and consistent performance, though at a higher unit cost than carbon film.

Key Electrical Specifications to Understand

Regardless of element type, every potentiometer is defined by a core set of specifications. Knowing these before you contact a manufacturer speeds up your project significantly.

  • Resistance value and tolerance: the nominal end-to-end resistance (for example 10 kΩ) and how far the actual value may deviate (typically ±10% or ±20% for standard parts, tighter for precision parts).
  • Power rating: the maximum power the element can dissipate continuously, usually derated linearly as the wiper moves away from the centre of travel.
  • Taper: linear (B), audio/logarithmic (A) or reverse-audio (C), determining how resistance changes with position.
  • Temperature coefficient: how much the resistance drifts with temperature, expressed in ppm/°C. Precision instruments may require 100 ppm/°C or better.
  • Mechanical and rotational life: the number of full rotation cycles the component can survive while staying within specification — from roughly 10,000 cycles for economy parts to over 10 million for conductive plastic types.
  • Noise: contact noise generated as the wiper moves, quantified in mV per volt of applied voltage. Cermet and conductive plastic elements are notably quieter than carbon film.
  • IP rating and sealing: whether the element is protected against dust and moisture, essential for outdoor, automotive and food-processing environments.

Precision Manufacturing and Testing

Every potentiometer that leaves our factory undergoes rigorous electrical, mechanical and environmental testing to ensure consistent performance and long service life. Our ISO 9001 quality management system governs the entire process, from incoming material inspection to final electrical testing before packing.

Key tests in our production line include: resistance value and tolerance verification against the datasheet specification; taper conformity measurement to confirm the output curve matches the requested characteristic; rotational life testing on sample lots to validate endurance; torque and feel checks for products where the operator interface matters; and soldering, vibration and temperature cycling tests that simulate the conditions the component will face in the field. Parts destined for automotive and industrial customers receive additional environmental screening.

This testing is not a formality. When a customer's end product has a five-year service life, the potentiometer inside it must hold its electrical characteristics for that entire period — and that guarantee is built during manufacturing, not after it.

Custom Potentiometers for Your Application

Standard potentiometers cover the majority of designs, but many of our customers need something specific: a particular shaft length, a special taper, a detented feel, multi-gang sections, or an unusual resistance value that no catalogue part offers.

Our OEM/ODM program supports custom element selection, shaft and bushing options, terminal configurations, packaging and full private-label branding. Low minimum order quantities mean even prototyping and pilot runs are practical, and our in-house engineering team works from your specification, drawing or even a sample part to deliver exactly what your product needs.

If you are designing a new product or improving an existing one, talk to our engineering team about your potentiometer requirements — we will help you select the right element technology and configuration for your application, timeline and budget.