Potentiometer Pin Diagram: Understanding the 3 Terminals

Potentiometer Pin Diagram: Understanding the 3 Terminals — interactive diagram. Open it in the editor to customise components and wiring.

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A potentiometer pin diagram identifies the three terminals of a variable resistor: the two fixed ends of the resistive track (connected to the supply reference voltages) and the central wiper that slides between them to produce a variable output voltage.

A potentiometer (commonly shortened to 'pot') is a three-terminal resistive component that functions as a mechanically adjustable voltage divider. It consists of a resistive element — typically carbon film, cermet, conductive plastic, or wire-wound — with a moveable contact (wiper) that slides along its length. The total resistance between the two end terminals is fixed and determines the component's rating (for example, 10 kΩ). The wiper terminal provides a variable resistance fraction of this total, dependent on its position.

Terminal identification:

Terminal 1 (CW or high end): One end of the resistive track. By convention, when the shaft or slider is rotated or moved fully clockwise (for rotary pots), this terminal represents the maximum resistance from the wiper to Terminal 3. In a voltage divider circuit, this terminal often connects to the high reference voltage (VCC, +V, or the supply positive).

Terminal 2 (wiper, W, or centre): The moving contact. This is the output terminal. The resistance from Terminal 1 to Terminal 2, and from Terminal 2 to Terminal 3, changes as the wiper moves. At the midpoint, both resistances are equal to half the total resistance.

Terminal 3 (CCW or low end): The opposite end of the resistive track. In a voltage divider circuit, this terminal connects to the low reference voltage (GND, 0 V, or the negative supply). Rotating the shaft fully counterclockwise brings the wiper to this end.

As a voltage divider, if VCC is applied to Terminal 1, 0 V to Terminal 3, and the wiper (Terminal 2) is at the midpoint, the output voltage at Terminal 2 is VCC ÷ 2. Moving the wiper toward Terminal 1 increases the output voltage toward VCC; moving it toward Terminal 3 decreases it toward 0 V.

Variants: Rotary potentiometer: shaft rotates through an arc (typically 270–300° for standard single-turn types; multi-turn pots provide 3 to 25 turns for finer adjustment). Linear (slide) potentiometer: slider moves along a straight track. Digital potentiometer: a digitally controlled resistance ladder replacing the mechanical wiper; controlled via SPI or I2C. Taper: linear (B-taper) provides proportional resistance change with angle; audio taper (A-taper) provides a logarithmic change matching human hearing perception. Trimpot (trimmer potentiometer): small, panel or PCB-mount pot for infrequent set-and-forget adjustment, typically adjusted with a screwdriver.

How to wire potentiometer pin diagram

Identify the potentiometer's three terminals physically Single-gang rotary potentiometers typically have three terminals on the rear of the body or as radial leads from a PCB package. Panel-mount pots often have a flat mounting plate with the shaft extending forward and terminals on the rear. The wiper terminal is usually the centre terminal; the outer two are the resistive track ends. Confirm with a multimeter — the outer two terminals should show the full rated resistance; the centre terminal shows a variable fraction.
Determine the required taper for the application Choose audio taper (A or log) for volume and tone controls where a perceptually smooth response is needed. Choose linear taper (B or lin) for position sensing, reference adjustment, or any application where output should track shaft position proportionally. The taper type is marked on the pot body (A or B code, or written out) and on the datasheet.
Wire Terminal 1 and Terminal 3 to the reference voltages Connect Terminal 1 (CW end) to the higher reference voltage and Terminal 3 (CCW end) to the lower reference voltage (or ground). In a simple volume control circuit: Terminal 1 connects to the audio signal source; Terminal 3 connects to ground. In a position sensor circuit: Terminal 1 connects to VCC; Terminal 3 connects to GND. The voltage from Terminal 1 to Terminal 3 determines the output voltage range available at the wiper.
Connect Terminal 2 (wiper) to the output load Wire Terminal 2 (wiper) to the input of the next stage — an amplifier input, ADC input, Arduino analogue pin, or signal line. The load impedance connected to the wiper affects linearity: for best accuracy, the load impedance should be at least 10× the total pot resistance. A 10 kΩ pot driving a 1 kΩ load will show significant non-linearity and the output will not track the shaft angle accurately.
Verify the wiper direction and adjust if needed Turn the shaft fully clockwise and measure the output voltage at the wiper. If it reads VCC (high reference), the wiring convention matches the standard clockwise-equals-maximum convention. If it reads GND, Terminal 1 and Terminal 3 are reversed. Swap them to correct the direction, or adjust in software if the output is read by a digital system and reversal is acceptable.
Secure mechanical mounting and provide strain relief For panel-mount pots, tighten the mounting nut to the manufacturer's specified torque — over-tightening can distort the pot body and affect the wiper contact pressure. Ensure the wiring leads are not under mechanical tension. For PCB-mount pots, ensure soldering is complete and free of cold joints, which cause intermittent contact. Trimp potentiometers should be adjusted using a non-metallic screwdriver to avoid ESD and to prevent short circuits on nearby PCB pads.

Specifications

Terminal 1 (CW end)	One end of resistive track; at full clockwise, wiper resistance to T3 is maximum
Terminal 2 (wiper, W)	Moving contact; output terminal; resistance to T1 and T3 varies with shaft position
Terminal 3 (CCW end)	Opposite end of resistive track; at full counterclockwise, wiper resistance to T1 is maximum
Total resistance tolerance	Typically ±10–20% for carbon film; ±5% for cermet; exact to tighter tolerance for precision wire-wound
Common resistance values	500 Ω, 1 kΩ, 5 kΩ, 10 kΩ, 20 kΩ, 50 kΩ, 100 kΩ, 500 kΩ, 1 MΩ
Typical power rating (panel mount)	0.25 W to 2 W; wirewound types available to higher ratings
Electrical travel (rotary, standard single-turn)	Typically 270–300° (standard single-turn); 3–25 turns (multi-turn types)
Taper designations	A = audio/log taper; B = linear taper (IEC convention; note some manufacturers swap A and B)

Safety warnings

Potentiometers are low-voltage signal and control components. However, if used in a circuit connected to mains voltage (for example, as a phase control element in older lamp dimmers or motor speed controllers), both end terminals and the wiper may be at mains potential. In such applications, treat all terminals as live and follow full electrical safety procedures. Fixed mains installation work must be done by a licensed electrician.
Never apply a voltage across the potentiometer terminals that exceeds the component's rated maximum voltage. Exceeding this rating can arc over the resistive track or damage the wiper contact, causing the pot to become noisy, non-linear, or fail open-circuit.
When adjusting trimmer potentiometers (trimp pots) on energised PCBs, use an insulated non-metallic screwdriver to avoid short-circuiting adjacent PCB pads or tracks. A metal screwdriver can also cause ESD damage to nearby ICs.

Tools needed

Multimeter (resistance mode for terminal identification, voltage mode for circuit verification)
Insulated or non-metallic screwdriver (for trimmer potentiometers)
Soldering iron and solder (for PCB-mount pots)
Spanner or nut driver (for panel-mount pot mounting nut)
Wire stripper (for signal wire connections)
Oscilloscope (for checking pot noise/audio taper linearity in audio applications)

Common mistakes

Connecting a low-impedance load to the wiper of a high-value pot: a 100 kΩ pot driving a 10 kΩ input will show significant output non-linearity and compression because the load forms a voltage divider with the wiper resistance, distorting the expected linear or log response.
Confusing audio taper (A) and linear taper (B): using a linear pot as a volume control produces a control that feels very responsive at the low end and barely moves the volume at the high end; using an audio pot for a position sensor produces a sensor with highly non-linear output.
Using a pot with a power rating below the continuous power dissipation of the circuit: the product of voltage across the pot and current through it must not exceed the pot's watt rating, or the resistive element will overheat and shift in value or fail.
Leaving the wiper terminal unconnected when using the pot as a rheostat: if the connected end terminal fails or is accidentally disconnected, the circuit becomes open-circuit. Connect the unused wiper terminal to the adjacent end terminal to provide a redundant path and limit open-circuit failure.

Troubleshooting

Pot output is noisy or crackles when the shaft is turned: Cause: Worn or contaminated wiper contact; oxidation on the resistive track Fix: For audio applications, apply an appropriate contact cleaner (electrical contact cleaner spray, not penetrating oil) sparingly through the pot body opening while rotating the shaft. If noise persists, the pot has reached end of mechanical life and must be replaced. There is no practical repair for a worn resistive track.
Output voltage jumps to full scale or zero when shaft is near one extreme: Cause: Wiper has reached end of travel and the pot does not have a full 'dead band' at the extreme; or the wiper contact is lifting off the track at the end of travel Fix: This is normal behaviour if the shaft is rotated to the physical stop. If it occurs before the physical stop, the pot may have a defective or worn wiper at that end. Replace the pot. For position sensing applications, limit mechanical travel to stay within the pot's specified electrical travel (typically 270° for a 300° physical rotation range).
Output voltage is non-linear and does not track shaft position as expected: Cause: Load impedance at the wiper is too low relative to the pot resistance; or an audio-taper pot has been used where a linear taper is needed Fix: Measure the load impedance at the wiper terminal. If it is less than 10× the pot's total resistance, the loading error is significant. Replace the pot with a lower-value pot (lower internal resistance relative to the load) or buffer the wiper with a unity-gain voltage follower (op-amp buffer) to present a high impedance to the pot.

Frequently asked questions

How do I identify the three terminals on a potentiometer without a datasheet?

Use a multimeter in resistance mode. Measure resistance between all three terminal pairs. The pair showing the highest and fixed resistance value is the two end terminals (the full resistive track). The terminal that shows a variable resistance to the other two as the shaft is turned is the wiper. The end terminals will each show increasing and decreasing resistance to the wiper as it moves.

What is the difference between a potentiometer and a rheostat?

A potentiometer uses all three terminals as a voltage divider. A rheostat uses only two terminals — one end and the wiper — to provide a variable resistance in series with a circuit, not a voltage division. The same physical component can be wired as either: connect all three terminals for potentiometer operation, or connect only one end terminal and the wiper for rheostat operation. Connecting the unused end to the wiper prevents the full track from becoming open-circuit.

What is audio taper (A-taper) versus linear taper (B-taper)?

Linear taper provides a resistance change directly proportional to shaft rotation: at 50% rotation, 50% of the total resistance is between the wiper and each end. Audio taper provides a logarithmic change designed to match human hearing perception: at 50% rotation, approximately 10–20% of the total resistance has been traversed. Audio taper is used for volume controls; linear taper is used for most other adjustment functions.

Can a potentiometer wear out?

Yes. The wiper contact and resistive track experience mechanical wear with each movement. Carbon-film potentiometers are rated for approximately 10 000–50 000 rotations before the wiper wear causes increased noise (a scratching sound during adjustment) or an intermittent open circuit. Cermet and conductive-plastic potentiometers have lower wear rates. Wirewound potentiometers have step-like resolution (one turn of wire per step) but very long service life.

What happens if the wiper terminal is left unconnected?

If the wiper terminal is left unconnected and the pot is used with only its two end terminals, it functions as a fixed resistor with a value equal to its full rated resistance. No harm occurs from leaving the wiper unconnected. However, if the pot is wired as a voltage divider with the wiper as output, an unloaded wiper in a high-impedance circuit produces the expected voltage; a heavy load at the wiper terminal will affect linearity.