PR-18 Series Single-Turn Rotary Carbon Potentiometers
Single-turn rotary carbon potentiometer with 18mm metal case diameter
Carbon resistive track on resin-modified paper base substrate
Resistance range 120Ω to 2.2MΩ (E3 series values) for linear law; 1kΩ to 1MΩ for logarithmic and reverse logarithmic laws
Three resistance law options: linear (A), logarithmic (B), and reverse logarithmic (C)
Maximum power dissipation 0.2W at 40°C for linear law; 0.1W for logarithmic and reverse logarithmic laws
Maximum working voltage 200V across all resistance laws
Total mechanical rotation angle 300° ±5°
Climatic category 25/070/10
Available as single or tandem (dual-gang) units, with plastic or metallic spindle
Optional integrated switch rated at 120V/1A AC or 16V/2A DC
Terminals designed for PCB mounting or direct soldering
Multiple spindle end types and lengths available in 4mm and 6mm diameters
What are the PR-18 Series Single-Turn Rotary Carbon Potentiometers?
The PR-18 is an 18mm single-turn rotary carbon potentiometer housed in a metal case, built around a carbon resistive track deposited on a resin-modified paper base. The 18mm body diameter places the PR-18 between compact 16mm panel controls and larger power-rated potentiometers, making it a practical choice where slightly higher power dissipation or a larger panel feel is required without a significant increase in enclosure space. The metal case provides dimensional stability, mechanical durability, and a consistent mounting interface for standard panel cutouts.
Three resistance law profiles are offered. The linear (A) law covers 120Ω to 2.2MΩ using E3 preferred values, providing a direct, proportional relationship between shaft rotation and resistance output. The logarithmic (B) and reverse logarithmic (C) laws both span 1kΩ to 1MΩ, shaped to complement the non-linear perception of audio signals by the human ear and to support inverse attenuation curves in signal routing and mixing applications respectively. All three laws share a 300° ±5° total mechanical rotation angle.
The maximum power dissipation for the linear law version is 0.2W at 40°C ambient, while logarithmic and reverse logarithmic variants are rated at 0.1W. Power dissipation derates linearly from 100% at 40°C to 25% of rated power at 70°C. The maximum working voltage is 200V for all law variants. Resistance tolerance is ±20% as standard for values up to 220kΩ, widening to ±30% for higher values, with tighter tolerances of ±5% and ±10% available on request for values at or below 470kΩ.
The PR-18 range covers a wide variety of mechanical configurations. Single units are offered in 5mm and 6mm spindle diameter variants (PR 185 and PR 186 respectively), each available with or without an integrated on/off switch (suffix S56), with or without a tap, and for either direct panel assembly or PCB mounting. Tandem versions (PR 18 G series) provide dual-gang tracking for stereo and balanced signal applications, with synchronisation specifications of ≤2dB for linear law across the 10–90% travel range and ≤4dB for logarithmic law across the 0–40dB attenuation range. Spindle end types P1, P3, P5, P5.1, P5.2, and P6 cover plain, flatted, and shaped profiles in standard lengths from 8mm to 40mm, accommodating knob fitment across a broad range of panel depths and knob styles. All potentiometers are marked with rated resistance and date of manufacture and supplied in bulk plastic bag and carton box packaging.
PR-18 Series Single-Turn Rotary Carbon Potentiometers Specifications
A practical overview for engineers and procurement teams evaluating resistive solutions.
Model: PR-18
Resistor type: Variable
Description: 18.5mm, carbon single turn potentiometer
Power Rating: 0.2W
Resistance (Ω): E3, 120~2.2M
Tolerance (%): ±5, ±10, ±20, ±30
Applications of the PR-18 Series Single-Turn Rotary Carbon Potentiometers
Where RARA variable resistors are deployed in the field.
Consumer and professional audio equipment — volume, balance, tone, and channel level controls
Video and broadcast equipment — signal level, brightness, and contrast adjustment
Domestic appliances and white goods — user-facing rotary control interfaces requiring moderate power rating
Hi-fi and home theatre systems — source selection and output level controls with integrated switch
Industrial control panels — setpoint and reference level adjustment in process control equipment
Power supply circuits — output voltage and current limit setting
Motor speed controllers — speed reference and acceleration ramp adjustment
Lighting control equipment — dimmer intensity and scene level adjustment
Mixing consoles and audio production equipment — channel fader and send level controls
General-purpose electronic equipment — panel-mounted rotary controls where 18mm body diameter and E3 resistance values are required
Related Products of the PR-18 Series Single-Turn Rotary Carbon Potentiometers
Model: PC-199
Resistor type: Variable
Description: 19mm, hermetic cermet potentiometer
Power Rating: 1W
Resistance (Ω): 100~2.2M
Tolerance (%): ±10, ±20, ±30
Model: SP
Resistor type: Variable
Description: 29mm, carbon single turn potentiometer
Power Rating: 1W
Resistance (Ω): 10kR (E6)
Tolerance (%): ±10
Model: CW-18
Resistor type: Variable
Description: 18.5mm, hermetic cermet potentiometer
Power Rating: 1W
Resistance (Ω): 100~2.2M
Tolerance (%): 20, ±30
TCR (ppm/C): 300
Model: DM
Resistor type: Variable
Description: Wire wound potentiometer
Power Rating: 0.75W
Resistance (Ω): 22~47k
Tolerance (%): ±2.5, ±5, ±10
Why Choose RARA Variable Resistors
What sets RARA apart for engineers and procurement managers in industrial and automotive markets.
01
Full Spectrum Coverage
From 0.1W carbon signal potentiometers to 3000W industrial wire wound rheostats — RARA covers the complete variable resistor spectrum from a single ISO 9001 certified supplier.
02
Hermetic Sealed Options
PC-199 and CW-18 hermetically sealed cermet models resist moisture, dust, and contamination — extending service life in outdoor, marine, and industrial environments where standard potentiometers degrade rapidly.
03
Precision Wire Wound
DM, DOW, and DG precision wire wound potentiometers deliver the accuracy and repeatability needed for calibration, instrumentation, and closed-loop feedback applications.
04
Global Track Record
Trusted by Siemens, Rockwell, Schneider Electric, and Hanwha — deployed in industrial control and power regulation systems across six continents.
