The **261-R** is a specific part number typically associated with high-precision, wirewound chassis-mount resistors manufactured by companies like **Ohmite** (specifically the 200 Series). These components are designed for industrial applications requiring high power dissipation and durability. --- ### 1. Technical Specifications The "261-R" designation usually refers to a specific resistance value (often 0.1 $\Omega$ or 1 $\Omega$ depending on the series prefix) within the 200 Series power resistors. | Feature | Specification (Typical) | | :--- | :--- | | **Component Type** | Fixed Resistor | | **Construction** | Wirewound (with vitreous enamel coating) | | **Mounting Type** | Chassis Mount / Through-bolt | | **Power Rating** | 12W to 100W+ (Depending on physical size) | | **Tolerance** | ±5% or ±10% | | **Core Material** | Ceramic / Steatite | --- ### 2. Key Internal Components The 261-R series is built to handle extreme thermal stress. Its architecture consists of four main parts: 1. **Resistive Element:** A high-quality resistance wire (usually Nickel-Chrome or Copper-Nickel) wound around a ceramic core. 2. **Ceramic Core:** A hollow cylindrical tube that provides electrical insulation and acts as a heat sink. 3. **Vitreous Enamel Coating:** A glass-like protective layer that shields the wire from moisture, oxidation, and mechanical damage while aiding heat dissipation. 4. **Terminals:** Solder-coated lugs or "quick-connect" tabs protruding from the ends for wiring. --- ### 3. Common Applications Due to their rugged nature, these resistors are found in heavy-duty environments: * **Dynamic Braking:** Dissipating excess energy in motor control circuits. * **Voltage Dropping:** Used in power supplies to reduce voltage levels for specific sub-circuits. * **Load Testing:** Acting as a dummy load for testing batteries or power amplifiers. * **Heating Elements:** In specialized industrial equipment where controlled heat is required. --- ### 4. Handling and Installation * **Thermal Management:** These parts get extremely hot during operation. They should be mounted away from heat-sensitive components (like electrolytic capacitors). * **Mounting:** Often requires a "through-bolt" or a specific mounting bracket to secure the ceramic tube to the chassis. * **Clearance:** Ensure adequate airflow around the vitreous enamel body to prevent thermal runaway.