The part number **C3-R39-10** typically refers to a specific type of **Current Sense Resistor** (Shunt Resistor) often manufactured by brands like *Caddock* or similar high-precision component specialists. It is designed to measure current by providing a low, stable resistance path. ### 1. Component Breakdown The alphanumeric code generally defines the series, resistance value, and tolerance: | Part Segment | Meaning | Description | | :--- | :--- | :--- | | **C3** | Series/Package | Refers to the physical size and power rating (often a 3-Watt rating). | | **R39** | Resistance Value | "R" acts as a decimal point. **0.39 Ohms** ($\Omega$). | | **10** | Tolerance | Indicates a **10%** tolerance range (or sometimes refers to a specific voltage/temp coefficient). | --- ### 2. Technical Specifications While exact specs can vary by manufacturer, a standard "C3" series resistor typically follows these parameters: * **Resistance:** 0.39 $\Omega$ * **Power Rating:** 3 Watts (at standard ambient temperatures). * **Type:** Metal film or wirewound (non-inductive designs are common for this series). * **Mounting:** Through-hole (Axial leads). * **Function:** Used primarily for current sensing or current limiting in power supplies. --- ### 3. Typical Applications These components are found in circuits where monitoring electrical flow is critical: 1. **Motor Control:** Measuring the current drawn by a motor to prevent stalls or over-torque conditions. 2. **Power Supplies:** Used in feedback loops to regulate output current. 3. **Battery Management (BMS):** Monitoring charge and discharge cycles in battery packs. 4. **Audio Amplifiers:** Acting as emitter resistors in output stages to stabilize the circuit. --- ### 4. Why use 0.39 Ohms? A value like $0.39\Omega$ is a "low-ohm" value. It is chosen to minimize power loss ($P = I^2 \times R$) while still generating a measurable voltage drop ($V = I \times R$) that can be read by an Analog-to-Digital Converter (ADC) or an Operational Amplifier. ---