The **FCR-4W5-R** is a specific electronic component identifier typically associated with **Power Resistors**, specifically a **Flameproof Carbon Film Resistor**. Below is a detailed breakdown of its specifications, construction, and technical characteristics. --- ## 1. Technical Specifications The part number follows a standard industry nomenclature for passive components. | Feature | Specification | Description | | :--- | :--- | :--- | | **Component Type** | Carbon Film Resistor | Uses a carbon film deposited on a ceramic core. | | **Power Rating** | 1/4W (0.25 Watts) | The "4W" in some series denotes the size/rating logic. | | **Resistance Value** | 5.1 Ohms (Typically) | The "5" in "4W5" often refers to the base multiplier. | | **Tolerance** | ±5% (J) | Standard precision for carbon film types. | | **Safety Feature** | Flameproof | Designed not to ignite under severe overload. | | **Mounting** | Through-Hole | Axial leaded for PCB mounting. | --- ## 2. Component Construction The FCR series is engineered for reliability in power-sensitive circuits. ### Materials * **Core:** High-grade ceramic rod providing thermal stability. * **Resistive Element:** A thin film of carbon vacuum-deposited onto the core. * **Coating:** A multi-layer non-flame coating (usually light grey or pink) that prevents combustion if the resistor fails due to excessive heat. * **Terminals:** Tinned copper leads for easy soldering. ### Key Characteristics 1. **Pulse Handling:** Better pulse load capability compared to metal film resistors. 2. **Heat Dissipation:** Designed to operate at high temperatures without melting or catching fire. 3. **Stability:** Maintains resistance stability under normal operating conditions, though carbon film has a higher temperature coefficient than metal film. --- ## 3. Applications The FCR-4W5-R is commonly used in environments where safety and cost-effectiveness are priorities: * **Power Supplies:** Used as a bleeder resistor or for current limiting. * **Consumer Electronics:** Found in TVs, monitors, and home appliances. * **Inrush Current Limiting:** Protecting sensitive components during initial power-up. * **Safety Circuits:** Used where a "fusible" or non-flammable failure mode is required. --- ## 4. Part Number Decoding (Typical) While manufacturers vary slightly, the code usually breaks down as follows: ```text FCR - 4W - 5R - [Suffix] | | | | Series Power Resistance Packaging/Tolerance ``` ---