Adjustable Power Resistor

Part Number	Description / PDF	Quantity
D75K40KE Ohmite	RESISTOR POWER ADJ 40K OHM 75W	0
D12K750 Ohmite	RESISTOR POWER ADJ 750 OHM 12W	2
D50K20K Ohmite	RESISTOR POWER ADJ 20K OHM 50W	0
E300KR40E Ohmite	RESISTOR POWER ADJ 0.4 OHM 300W	0
D25K200E Ohmite	RESISTOR POWER ADJ 200 OHM 25W	0
D50K12K Ohmite	RESISTOR POWER ADJ 12K OHM 50W	0
D175K2K5 Ohmite	RESISTOR POWER ADJ 2.5K OHM 175W	0
D12K4K5E Ohmite	RESISTOR POWER ADJ 4.5K OHM 12W	0
D12K150 Ohmite	RESISTOR POWER ADJ 150 OHM 12W	0
D12K300E Ohmite	RESISTOR POWER ADJ 300 OHM 12W	0
E375K80RE Ohmite	375W 80 OHMS VIT CORRIB 10%	0
D12K10R Ohmite	RESISTOR POWER ADJ 10 OHM 12W	5
E300K5R0 Ohmite	RESISTOR POWER ADJ 5 OHM 300W	0
E300KR40 Ohmite	RESISTOR POWER ADJ 0.4 OHM 300W	0
E300K8R0 Ohmite	RESISTOR POWER ADJ 8 OHM 300W	1
D75K4K5E Ohmite	RESISTOR POWER ADJ 4.5K OHM 75W	0
D25K3R0 Ohmite	RESISTOR POWER ADJ 3 OHM 25W	0
D100K1K0 Ohmite	RESISTOR POWER ADJ 1K OHM 100W	0
D25K2K5 Ohmite	RESISTOR POWER ADJ 2.5K OHM 25W	4
E300KR50E Ohmite	RESISTOR POWER ADJ 0.5 OHM 300W	0

Adjustable Power Resistor

1. Overview

Potentiometers, variable resistors, and adjustable power resistors are three-terminal devices that allow manual or automated adjustment of electrical resistance. These components play a critical role in controlling voltage, current, and power in electronic circuits. Their ability to provide precise resistance tuning makes them essential in applications ranging from consumer electronics to industrial automation. Adjustable power resistors specifically handle high-power loads while maintaining stable performance.

2. Main Types and Functional Classification

Type	Functional Characteristics	Application Examples
Wirewound Potentiometer	High precision, high-temperature tolerance, durable	Power supply calibration, industrial motor control
Carbon Composition Potentiometer	Low cost, moderate noise, compact size	Audio volume control, consumer electronics
Digital Potentiometer	Digital interface, programmable resistance, no moving parts	Smart thermostats, IoT devices, medical equipment
Cermet Potentiometer	Stable resistance, low temperature coefficient	Aerospace systems, precision instrumentation
Adjustable Power Resistor	High power dissipation (up to 1000W), robust heat management	Electric vehicle charging, industrial heating systems

3. Structure and Composition

Typical components include:
- Resistive Element: Wirewound (nickel-chromium alloy), carbon film, or conductive plastic
- Wiper Contact: Gold-plated bronze or phosphor bronze for low contact resistance
- Housing: Flame-retardant plastic or metal casing for thermal protection
- Adjustment Mechanism: Rotary knob, linear slider, or digital control interface
- Terminals: Copper or brass terminals with solderable coatings

4. Key Technical Specifications

Parameter	Description	Importance
Resistance Range	Typically 10 to 10M for potentiometers, up to 100k for power resistors	Determines adjustability range
Power Rating	0.1W to 1000W depending on construction	Defines maximum power handling
Resolution	Analog: 0.1% step; Digital: 8-16 bit precision	Controls tuning accuracy
Temperature Coefficient	50-500 ppm/ C	Measures stability under thermal stress
Life Cycle	10,000-100,000 rotations (mechanical)	Determines durability

5. Application Fields

Consumer Electronics: Audio equipment (volume control), gaming controllers
Industrial: CNC machine calibration, process control systems
Automotive: Electric vehicle battery management, throttle position sensors
Medical: MRI machine parameter adjustment, infusion pump control
Renewable Energy: Solar inverter power optimization, wind turbine pitch control

6. Leading Manufacturers and Representative Products

Manufacturer	Product Series	Key Features
Bourns Inc.	3382P Series	Miniature trimmer potentiometer with 0.1% resolution
Vishay Precision Group	DHP10 Series	High-power wirewound resistor (1000W, 0.25% tolerance)
TE Connectivity	Precision Potentiometers	Military-grade cermet resistors (MIL-PRF-39023 qualified)
Analog Devices	AD5293 Digital Potentiometer	1024-position I C-controlled resistor ( 1% end-to-end tolerance)

7. Selection Guidelines

Key considerations:
- Power Requirements: Select resistors with 20% higher power rating than maximum load
- Environmental Conditions: Choose sealed enclosures for high-humidity environments
- Precision Needs: Use digital potentiometers for sub-1% accuracy requirements
- Cost Optimization: Balance wirewound (high cost, high durability) vs. carbon film (lower cost, shorter lifespan)
- Mounting Style: Through-hole for high vibration environments, surface-mount for PCB integration

8. Industry Trends

Future developments include:
- Miniaturization: 0402 package digital potentiometers entering mass production
- Smart Integration: IoT-enabled resistors with real-time resistance monitoring
- Material Innovation: Graphene-based resistive elements improving thermal stability by 40%
- Automated Adjustment: AI-controlled power resistors for dynamic load balancing
- Environmental Compliance: RoHS-compliant conductive plastics replacing cadmium-based compounds