How to Wire a Potentiometer: Pinout, Diagrams, and PCB Examples

A potentiometer is a three-terminal variable resistor that adjusts voltage or resistance as a wiper turns. Correct potentiometer wiring depends on which of the three terminals get used, whether the goal is a voltage divider, a two-terminal variable resistor, or a microcontroller input.

This guide covers pin identification, wiring diagrams for both configurations, an Arduino connection example, and how those choices carry through to schematic and PCB footprint selection.

Key Takeaways

• Identifying a potentiometer's three terminals is the first step before any wiring diagram produces the expected result.
• Wiring a potentiometer as a voltage divider uses all three terminals to produce an adjustable output between two fixed points.
• Choosing and adding a potentiometer to a PCB requires matching the footprint's pad numbering to the part's physical terminal arrangement.

Potentiometer Wiring Basics: Pinout and How It Works

A potentiometer contains a fixed resistive track and a movable contact called the wiper. The track spans the two outer terminals, and its total resistance stays fixed no matter where the wiper sits. The wiper taps the track at a variable point, so resistance between the wiper and either outer terminal changes as the wiper turns.

Most through-hole and panel-mount parts are three-pin potentiometers. 3-pin potentiometer wiring starts with identifying which terminal is which:

1. Terminal A (fixed): one end of the resistive track, often labeled pin 1.
2. Wiper (adjustable): the center terminal, often labeled pin 2, that taps the track at a variable position.
3. Terminal B (fixed): the other end of the track, often labeled pin 3.

Pin numbering is not standardized across manufacturers; some datasheets place the wiper on pin 1 or pin 3 instead of pin 2. Confirm terminal order against the specific datasheet before wiring or laying out a footprint.

Identifying terminals with a multimeter:

1. Set the meter to resistance mode and probe two outer pins. A steady reading that holds as the wiper turns confirms the two fixed terminals.
2. Move one probe to the remaining pin and turn the wiper. A reading that sweeps from near zero to the track's full value identifies the wiper.

How to Wire a Potentiometer as a Voltage Divider

A voltage-divider configuration uses all three terminals to produce an adjustable output between two fixed voltages.

1. Terminal A connects to the supply voltage (V+).
2. Terminal B connects to ground.
3. Wiper delivers the adjustable output, Vout. The output can connect to an analog input or set a comparator threshold.

Vout follows the standard voltage-divider relationship:

$$V_{out}=V_{+}\cdot \frac{R_{\text{wiper-to-B}}}{R_{total}}$$

Turning the wiper toward Terminal A raises Vout toward V+; turning it toward Terminal B lowers Vout toward ground.

Swapping Terminal A and Terminal B reverses the adjustment direction without changing anything else in the circuit, a common fix when output voltage increases opposite to what a panel label or firmware expects.

A typical potentiometer voltage divider sets a comparator's threshold or trims a reference feeding an analog-to-digital converter. Because the wiper usually feeds a high-impedance input into the comparator, loading error stays small.

How to Wire a Potentiometer as a Variable Resistor

A potentiometer also works as a two-terminal variable resistor, or rheostat, using only the wiper and one fixed terminal. Among the common types of variable resistors, potentiometers are especially useful when manual adjustment is required.

• Active terminals: the wiper and one outer terminal carry the current; resistance between them changes as the wiper turns.
• Unused terminal: the remaining outer terminal carries no current and can be left disconnected.
• Tying the unused terminal to the wiper: this connection reduces noise and adds a backup contact path if the wiper's connection to the track degrades over time.

Rheostat wiring suits low-current adjustment applications such as calibration trims, bias adjustment, and simple current-limiting controls.

Notably, running current through only part of the track concentrates heating in a smaller resistive area than a full divider does, so check the datasheet's power rating before relying on rheostat wiring beyond a low-current trim.

Linear vs. Logarithmic Taper

The taper of a potentiometer describes how resistance changes across wiper rotation.

1. Linear taper: resistance changes proportionally with rotation. Suited to position sensing and general-purpose voltage dividers.
2. Logarithmic (audio) taper: resistance changes along a curve matching human loudness perception. Suited to volume and gain controls.

Connecting a Potentiometer to Arduino

Wiring a potentiometer to an Arduino analog input follows the same connections as the voltage divider above:

1. Terminal A connects to 5V (or 3.3V).
2. Terminal B connects to GND.
3. Wiper connects to an analog pin such as A0.

The analog-to-digital converter (ADC) reads the wiper voltage and returns a value from 0 to 1023 on a 10-bit Arduino board. The ADC value tracks wiper position from one end of travel to the other.

int potPin = A0;
int reading = analogRead(potPin);
int scaled = map(reading, 0, 1023, 0, 255);

The Arduino map function converts the 0-1023 range to any scale a project needs, such as 0-255 for PWM brightness. Reversing the direction in software works like swapping the outer terminals in hardware: pass the map function's output range in reverse order, or swap Terminal A and Terminal B on the board.

Choosing and Adding a Potentiometer to a PCB

Moving from a breadboard diagram to a PCB design adds component selection and footprint verification.

Potentiometer Selection and PCB Design Factors

A schematic symbol for a potentiometer is generic: three terminals and a wiper arrow, without committing to a package or pin arrangement. The manufacturer part and its footprint are where the physical pin order gets fixed, but the physical pin order does not always match the symbol's numbering in schematic diagrams. Confirm the footprint's pad numbering against the part's physical terminal arrangement before finalizing layout.

Common wiring and layout mistakes

Bringing Potentiometer Wiring Into a Full Design

Getting potentiometer wiring right on a breadboard is only the first step. Carrying that same terminal mapping into a schematic and a footprint without errors takes verification from symbol to pad. Flux keeps schematic symbols, footprints, and shared component libraries connected, so a mislabeled wiper terminal gets flagged during DFM review instead of after a board comes back from fab.

Designers can also simulate circuits with AI before committing a voltage-divider or rheostat design to layout, or design circuits with natural language to rough out a potentiometer-based reference circuit in minutes. To wire, verify, and lay out a potentiometer circuit from first symbol to finished board, start a schematic in Flux.

FAQs

Which pin is the wiper on a potentiometer?

The wiper is typically the center pin on a three-pin potentiometer, though order varies by manufacturer. A datasheet check or multimeter test confirms the wiper pin on a specific part.

Can a potentiometer work with only two pins?

A potentiometer can work with only two pins by using the wiper and one outer terminal. Such a connection operates as a variable resistor (rheostat) instead of a voltage divider.

Why does my potentiometer work in reverse?

A potentiometer works in reverse when the outer terminals are wired opposite what the schematic or firmware expects. Swapping those connections, or reversing the mapped range in code, corrects the direction.

What happens if the wiper is left disconnected?

A disconnected wiper in a voltage-divider configuration produces a floating, unpredictable output. In rheostat mode, a disconnected wiper simply breaks the circuit.

What potentiometer value should I use?

Potentiometer value should match the surrounding circuit's impedance and target range. Common values run from 1 kΩ to 100 kΩ; lower values suit circuits sensitive to loading, and higher values suit high-impedance references.

Can a potentiometer control a high-current load directly?

A potentiometer should not control a high-current load directly, since the resistive track has a limited power rating and heats under sustained current. High-current loads need a potentiometer wired to control a transistor or MOSFET driver instead.