The **WJM-1A5W-R** is a specific model of a **Miniature Reed Relay**, typically used in telecommunications, security systems, and high-speed switching applications. It is designed to act as an electrically operated switch that uses an electromagnet to control the opening or closing of reed switch contacts. --- ### 1. Key Technical Specifications The following table outlines the general electronic characteristics of the WJM series (specifically the 1A5W-R variant): | Feature | Specification Details | | :--- | :--- | | **Contact Form** | 1 Form A (SPST-NO: Single Pole Single Throw, Normally Open) | | **Nominal Coil Voltage** | 5V DC | | **Switching Voltage (Max)** | 100V DC / 125V AC | | **Switching Current (Max)** | 0.5A | | **Carry Current (Max)** | 1.0A | | **Contact Rating** | 10W | | **Coil Resistance** | Approx. 500Ω (varies by specific manufacturer tolerance) | | **Package Type** | DIP (Dual In-line Package) | --- ### 2. Internal Components & Construction The WJM-1A5W-R consists of several critical electronic parts integrated into a small housing: * **Reed Switch:** A glass tube containing two ferromagnetic blades. These blades are plated with precious metals (like Rhodium or Ruthenium) to ensure low contact resistance and long life. * **Inductive Coil:** A copper wire winding wrapped around the glass tube. When 5V DC is applied, it creates a magnetic field. * **Magnetic Shielding (Optional):** Some variants include an internal metal shield to prevent electromagnetic interference (EMI) with neighboring components. * **Encapsulation:** The internal parts are molded in epoxy resin to protect against humidity, vibration, and dust. --- ### 3. Functional Mechanism 1. **De-energized State:** The reed blades are separated by a small gap. The circuit is "Open." 2. **Energized State:** When 5V is applied to the coil, the resulting magnetic flux pulls the reed blades together. 3. **Switching:** The circuit is "Closed," allowing current up to 0.5A to flow through the contacts. 4. **The "R" Suffix:** Often indicates a specific feature such as **RoHS Compliance** or a **Clamping Diode** integrated across the coil to protect driving circuits from "back EMF" spikes. --- ### 4. Common Applications * **Test & Measurement:** High-speed signal switching in automated test equipment (ATE). * **Security:** Door/window sensors or alarm control panels. * **Telecommunications:** Line switching and modem interfaces. * **Medical Equipment:** Isolation switching for sensitive sensors.