Potentiometer Wiring Diagram
This is a free printable potentiometer wiring diagram: download the diagram as SVG or open it and print to paper or PDF.
Wiring a potentiometer correctly requires connecting both fixed end terminals to the supply rails and taking the variable output from the centre wiper terminal — a common source of wiring confusion.
Understanding how to physically wire a potentiometer into a circuit is distinct from understanding its circuit theory. Many beginners wire only two of the three terminals, inadvertently connecting the pot as a rheostat rather than a voltage divider. This section covers the practical, physical wiring of a potentiometer for the most common real-world applications.
A standard single-gang rotary potentiometer mounted on a panel or PCB has three solder lugs or pins arranged in a row or arc. Looking at the component from the rear (solder side), with the shaft pointing away from you, the left pin is typically end terminal 1 (connected to the counter-clockwise end of the resistive track), the right pin is end terminal 3 (clockwise end), and the centre pin is the wiper. However, this orientation is not universal — always verify with a multi-meter before soldering.
For a voltage-divider (potentiometer) wiring: - Connect pin 1 to GND and pin 3 to the positive supply Vcc (or vice versa, which reverses the rotation direction). - Connect pin 2 (wiper) to the signal destination — ADC, op-amp input, or directly to a display.
For a rheostat (variable series resistor) wiring: - Connect one end terminal and the wiper in series with the load. Bridge the unused end terminal to the wiper to ensure full resistance range is available and to prevent an open-circuit at one extreme of travel.
In automotive and sensor applications, a position-sensing potentiometer (throttle position sensor, ride-height sensor) uses the full three-terminal wiring so the ECU can measure an accurate ratiometric voltage regardless of supply voltage fluctuations. The ratiometric output — V_out / Vcc — remains constant even as the battery voltage varies, which is why reference voltage quality matters.
For panel-mounted pots in audio or control gear, dress the three wires away from high-current or switching conductors to minimise noise coupling. Short, twisted or shielded wire between the pot and the PCB is best practice in sensitive audio circuits. Keep the wiper wire (centre pin) as short as possible since it presents the highest impedance point in the circuit.
Surface-mount trimmer potentiometers (trimpots) are adjusted once for calibration and then left in position. They are not intended for repeated user adjustment — selecting a panel pot for that purpose prevents premature track wear.
How to wire potentiometer wiring diagram
- Identify and confirm the wiper terminal before wiring Set a multi-meter to resistance mode. Measure all three pin combinations. The pair that gives a constant reading regardless of shaft position are the two end terminals; the pair that change as you rotate are each end terminal with the wiper. Mark the wiper pin before soldering.
- Determine the required rotation direction and assign supply rails accordingly Decide whether clockwise rotation should increase or decrease the output. For 'clockwise = increase': connect GND to the counter-clockwise end terminal (pin viewed from front-left) and Vcc to the clockwise end terminal. Swap these if the reverse direction is preferred.
- Solder or terminate the supply rails to the end terminals For through-hole panel pots, solder short wires to each end lug. Avoid touching the resistive track with the soldering iron — excessive heat transmitted through the lug can damage the element. Keep solder application brief (1–2 seconds per joint).
- Connect the wiper to the signal destination Solder the wiper pin to its destination using the shortest practical wire length. If the run is longer than a few centimetres in a noise-sensitive environment, use screened (shielded) wire with the screen grounded at the destination end only.
- Secure the pot mechanically before finalising wiring For panel-mount pots, tighten the mounting nut and washer before soldering the wires. Movement after soldering stresses the solder joints and can fracture them. For PCB-mount pots, confirm the body is flush against the PCB before reflow or hand soldering.
- Verify output with a multi-meter across the full rotation range Power the circuit and place the multi-meter positive probe on the wiper terminal and negative on GND. Rotate the shaft slowly from stop to stop. Confirm the voltage sweeps smoothly from near-zero to near-Vcc without any discontinuities or erratic jumps.
Specifications
| Typical pot resistance values | 100 Ω, 1 kΩ, 5 kΩ, 10 kΩ, 50 kΩ, 100 kΩ, 500 kΩ, 1 MΩ |
|---|---|
| End terminal resistance (residual) | Typically 1–50 Ω (varies by manufacturer and resistance value) |
| Wiper current maximum (carbon film) | 1–5 mA |
| Shaft diameter (standard panel-mount) | 6 mm round or 6.35 mm (1/4 in) — verify before ordering knob |
| Rotation angle (single-turn type) | 270° to 300° (mechanical travel between stops) |
| Rotation (multi-turn / trimmer) | 3, 10, or 25 turns — provides finer adjustment resolution |
| Operating temperature range (typical) | −20 °C to +70 °C (industrial types extend to −55 °C / +125 °C) |
Safety warnings
- Signal-level potentiometers are designed for low-voltage, low-current electronic circuits only. Do not wire a standard signal pot into a mains voltage circuit. Mains-rated components (rotary dimmers, motor speed controllers) use purpose-built triac or MOSFET-based assemblies — not simple resistive pots.
- Ensure the power supply is switched off before connecting or disconnecting wiring at the potentiometer terminals. Even low voltages can corrupt ADC calibration or damage sensitive op-amp inputs if accidentally shorted.
- When working on automotive throttle position sensors or other safety-critical potentiometer circuits, consult the vehicle service manual. Incorrect wiring of a throttle position sensor can cause unintended engine response. Refer to a qualified automotive technician.
- Wear appropriate eye protection when soldering — flux spatter is a hazard. Ensure adequate ventilation when soldering or using chemical contact cleaners.
Tools needed
- Digital multi-meter (resistance and DC voltage modes)
- Soldering iron (25–40 W for through-hole work) and suitable solder
- Wire strippers and flush cutters
- Helping hands or PCB vice for stable soldering
- Breadboard and jumper wires (for prototyping before soldering)
- Oscilloscope (optional, to check wiper noise under rotation)
Common mistakes
- Wiring only two terminals — end and wiper — when a voltage-divider output is needed; the output will then track from zero resistance to full resistance rather than from 0 V to Vcc.
- Installing the pot and tightening the panel nut after soldering the lead wires, causing mechanical stress on the solder joints.
- Connecting the wiper to a low-impedance load without a buffer, producing a loading error that makes the output curve appear non-linear.
- Confusing the physical orientation of the pot's pins — soldering Vcc to the wiper and the wiper signal to an end terminal results in a fixed voltage output regardless of shaft position.
- Using the incorrect taper type — fitting a logarithmic-taper pot into a position-sensing circuit where linear output is expected.
Troubleshooting
- Output voltage is fixed and does not change as the shaft is rotated
- Cause: The supply voltage is connected to the wiper pin, and one of the end terminals is taken as the output — wiper rotation only changes the resistance proportion seen at the end terminals, but if the supply is at the wiper, the output from an end terminal remains near-constant. Fix: Disconnect, verify the pin assignments with a multi-meter, and reconnect with Vcc and GND to the two end terminals and the signal taken from the centre wiper pin.
- Only half the voltage range is available — output goes from mid-point to Vcc but not to zero
- Cause: One end terminal is unconnected (floating). Only Vcc is applied to one end; the other end has no reference, so the lower half of the divider has no return path. Fix: Confirm both end terminals are connected: one to Vcc, one to GND. Use a multi-meter to verify continuity from each end terminal to the respective supply rail.
- Wiper output reads an incorrect voltage that does not match V_out = Vcc × (R_lower / R_total)
- Cause: Load impedance at the wiper is too low relative to the pot's total resistance, causing loading error. Fix: Measure the effective load impedance. If it is less than 10× the pot's resistance, insert a voltage-follower buffer (unity-gain op-amp) between the wiper and the load.
Frequently asked questions
Does it matter which way round I connect the two end terminals of a potentiometer?
Electrically, swapping pins 1 and 3 reverses the rotation direction of the output — turning clockwise increases voltage if pin 3 is at Vcc, or decreases voltage if pin 1 is at Vcc. Choose the orientation that gives the intuitive response for your control (clockwise = increase is the convention for most panel controls).
Why should I connect the unused end terminal to the wiper when wiring as a rheostat?
If the unused end terminal is left floating and the wiper reaches the extreme position of the track, the circuit is open and current through the load drops to zero — or in a motor circuit, control is completely lost. Bridging the unused end to the wiper ensures the resistance never goes above the design maximum.
Can I use a regular multi-turn trimmer pot for a volume control on audio equipment?
Technically yes, but trimpots are designed for infrequent adjustment — typically screwdriver-operated — and wear out quickly under repeated hand adjustment. Use a panel-mount, shaft-type potentiometer with an audio (logarithmic) taper for any user-facing volume control.
How do I wire a potentiometer for an Arduino analogue input?
Connect one end terminal to the 5 V (or 3.3 V) pin, the other end terminal to GND, and the wiper to an analogue input pin (A0–A5). The Arduino's ADC will read values from 0 to 1023 (10-bit) as the shaft is rotated. Keep the wire from the wiper to the analogue pin short to reduce noise pickup.
What size potentiometer should I use for a general-purpose adjustable voltage reference?
A 10 kΩ linear-taper potentiometer is the most versatile choice. It is low enough to drive most CMOS ADC inputs without a buffer, while high enough to limit current draw from a 5 V supply to 0.5 mA — well within the pot's ratings. Adjust up (100 kΩ) for ultra-low-power designs, or down (1 kΩ) if the load impedance is particularly low.