POLYSHINEHK / TECHNICAL GUIDE
Rotary potentiometers: a practical technical guide
A rotary potentiometer is a three-terminal variable resistor adjusted by turning a shaft. This guide explains how the parts of a rotary potentiometer work together, which parameters matter when specifying one, and the exact values we manufacture on our 9 mm F09K series.
How a rotary potentiometer works
Two outer terminals connect the ends of a resistive track; the centre terminal connects to a wiper that slides along that track as the shaft rotates. Wired across the full track it works as a voltage divider; wired to one end and the wiper it works as a simple variable resistor.
The resistive track can be carbon film (cost-effective, the usual choice for audio and general control) or conductive plastic. The relationship between shaft angle and output is the taper: B is linear, A and C are logarithmic curves used where human perception is non-linear, such as volume control.
Rotary potentiometers are continuous analogue devices, unlike rotary encoders, which output digital pulses. If you need absolute position sensing with a simple ADC input, a potentiometer is normally the simpler and cheaper answer.
What to specify
- Total resistance and tolerance
- Pick the resistance from the standard range, then check the tolerance band, which widens at the extremes of the range.
- Taper (A, B or C)
- Linear for measurement and set-point control, logarithmic for audio level and anything judged by ear.
- Gang number
- A single gang for mono or single-axis control, dual gang for stereo channels or two tracks driven by one shaft. Rated power and detent availability differ between them.
- Terminal style and mounting
- Top adjust or side adjust, with or without a sleeve bushing. This decides how the part sits relative to the board and the panel.
- Shaft type and length
- Splined, slotted, knurled and flatted shafts each suit different knobs. Shaft length also constrains whether a bushing can be fitted.
- Detents and rotational life
- A centre detent or 21-step detent gives tactile feedback; a long-life build is available where the control is turned frequently.
Typical applications
- Audio volume, tone, balance and gain controls in amplifiers, mixers, guitar pedals and instrument panels
- Set-point and trim adjustment on industrial controllers, power supplies and test equipment
- Speed, brightness and temperature dials on appliances and professional equipment
- Position and angle reference for joysticks, robotics and motion control assemblies
- Front-panel user controls on medical, laboratory and automotive interior modules
General specifications — F09K series
Values below are the published specifications for our 9 mm square insulated shaft rotary potentiometer. Other sizes and custom builds are quoted case by case.
- Résistance totale
- 1KΩ ~ 1MΩ
- Tolérance de résistance
- 500Ω < R < 1MΩ: ±20%; R ≤ 500Ω or R ≥ 1MΩ: ±30%
- Loi de résistance
- A, B, C
- Tension de service maximale
- AC 50V / DC 20V
- Puissance nominale
- Piste simple: 0.05W; Double piste: 0.03W
- Bruit de rotation
- Moins de 100mV
- Résistance d'isolement
- Plus de 100MΩ sous DC 250V
- Tenue en tension
- 1 minute sous AC 250V
- Résistance résiduelle
- Bornes 1~2 : moins de 20Ω ; bornes 2~3 : moins de 20Ω
- Écart entre pistes (double)
- −40dB ~ 0dB ± 3dB
- Nombre de pistes
- Piste simple (N) / double (G)
- Crans
- Sans cran / cran central (piste simple) / 21 crans (piste simple)
- Angle de rotation total
- 280° ± 10°
- Couple de rotation
- 10 ~ 90 gf·cm
- Résistance de butée
- 3,0 Kgf·cm min.
- Résistance à la traction
- 5,0 Kgf min.
- Couple des crans
- 30 ~ 120 gf·cm
- Durée de vie en rotation
- Standard : 15 000 cycles min. ; longue durée : 100 000 cycles min.
- Température de fonctionnement
- −10°C ~ +70°C
Dimensions and construction
- Dimensions du boîtier
- Carré de 9 mm
- Bornes et bague
- H réglage dessus sans bague / V latéral sans bague / A dessus avec bague / B latéral avec bague
- Hauteur H
- 0 sans objet (dessus) / 1 = 6,5 mm / 2 = 10,0 mm / 3 = 12,5 mm (latéral)
- Type d'axe
- Types F / N / C / Y / T / D / P / Q / K (fendus, moletés, etc.)
- Longueur d'axe
- Selon le code ; bague disponible uniquement pour un axe de plus de 20 mm
- Position en butée antihoraire
- Groupe C / A / D selon l'axe, 40° ± 10°
Build the exact part number
The F09K page includes a part-number builder that only allows valid option combinations, so the code you send us is one we can manufacture.