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.
- Resistência total
- 1KΩ ~ 1MΩ
- Tolerância da resistência total
- 500Ω < R < 1MΩ: ±20%; R ≤ 500Ω ou R ≥ 1MΩ: ±30%
- Curva de resistência
- A, B, C
- Tensão máxima de operação
- AC 50V / DC 20V
- Potência nominal
- Unidade simples: 0,05W; Unidade dupla: 0,03W
- Ruído rotacional
- Menos de 100mV
- Resistência de isolamento
- Mais de 100MΩ a DC 250V
- Tensão suportável
- 1 minuto a AC 250V
- Resistência residual
- Term. 1~2: menos de 20Ω; Term. 2~3: menos de 20Ω
- Erro de acoplamento (unidade dupla)
- −40dB ~ 0dB ± 3dB
- Número de seções
- Seção simples (N) / Seção dupla (G)
- Opção de detente
- Sem detente / detente central (seção simples) / 21 detentes (seção simples)
- Ângulo rotacional total
- 280° ± 10°
- Torque rotacional
- 10 ~ 90 gf·cm
- Resistência do batente
- 3,0 Kgf·cm mín.
- Resistência a empurrar-puxar
- 5,0 Kgf mín.
- Torque de clique
- 30 ~ 120 gf·cm
- Vida rotacional
- Padrão: mín. 15.000 ciclos; Longa vida: mín. 100.000 ciclos
- Faixa de temperatura de operação
- −10°C ~ +70°C
Dimensions and construction
- Tamanho do corpo
- 9 mm quadrado
- Terminal e bucha
- H ajuste superior sem bucha / V ajuste lateral sem bucha / A ajuste superior com bucha de manga / B ajuste lateral com bucha de manga
- Altura (H)
- 0 = N/D (somente ajuste superior), 1 = 6,5 mm, 2 = 10,0 mm, 3 = 12,5 mm (somente ajuste lateral)
- Tipo de eixo
- Tipos F / N / C / Y / T / D / P / Q / K (estriado, ranhurado, serrilhado e outros)
- Comprimento do eixo
- Especificado por código; bucha disponível apenas quando o comprimento do eixo excede 20 mm
- Posição total anti-horária
- Grupo C / A / D conforme o tipo de eixo, 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.