The **ESD-R-38** is a specific type of **EMI/RFI Suppression Core** (often referred to as a Ferrite Core) manufactured by KEMET. It is part of the ESD-R series designed to mitigate electromagnetic interference in round cables. --- ## 1. Technical Specifications The "38" in the part number typically refers to the outer diameter or the specific sizing sequence within the series. Below are the general specifications for this component: | Feature | Description | | :--- | :--- | | **Material Type** | Manganese Zinc (MnZn) or Nickel Zinc (NiZn) | | **Shape** | Toroidal / Round Ring Core | | **Application** | High-frequency noise suppression | | **Primary Function** | Converting noise energy into heat through impedance | | **Configuration** | Solid core (requires cable to be threaded through) | --- ## 2. Operating Principle The ESD-R-38 works as a **passive low-pass filter**. It allows low-frequency signals (like power or data) to pass through while providing high impedance to high-frequency noise. ### Impedance Characteristics * **Inductive Phase:** At lower frequencies, it acts like an inductor. * **Resistive Phase:** At high frequencies (where EMI occurs), the core becomes resistive, absorbing the EMI and dissipating it as a negligible amount of heat. --- ## 3. Key Electronic Parameters When integrating an ESD-R-38 into a circuit, engineers focus on the following data points: 1. **Impedance ($\Omega$):** Usually measured at 25 MHz and 100 MHz. Higher $\Omega$ indicates better noise suppression. 2. **Frequency Range:** ESD-R cores are often optimized for the FM band or high-frequency digital noise. 3. **Core Dimensions:** * **OD (Outer Diameter):** ~38mm * **ID (Inner Diameter):** The hole through which the wire passes. * **T (Thickness/Height):** Determines the total volume of magnetic material. --- ## 4. Installation & Usage To use the ESD-R-38 effectively in an electronic system: * **Cable Routing:** The wire or bundle of wires must be passed through the center of the ring. * **Turns:** Winding the wire through the core multiple times (2 or 3 turns) increases the impedance by the square of the turns ($Z \propto N^2$), providing better filtering for lower frequencies. * **Placement:** For maximum effectiveness, the core should be placed as close to the noise source (e.g., a switching power supply) or the entry point of the sensitive device as possible. --- ## 5. Typical Applications * Consumer electronics (TVs, PCs) * Industrial equipment controllers * Switching Power Supplies (SMPS) * Data communication lines