The **WJM-1C4W-R** is a specific type of **electromagnetic relay**, commonly used in industrial automation, security systems, and telecommunications. It is designed for low-power switching applications where reliability and isolation are required. --- ### 1. Key Technical Specifications Based on the standard nomenclature for this series, here are the primary electronic characteristics: | Parameter | Specification (Typical) | | :--- | :--- | | **Contact Form** | 1C (SPDT - Single Pole Double Throw) | | **Coil Voltage** | Typically 5V, 12V, or 24V DC (dependent on suffix) | | **Contact Rating** | Usually 1A to 3A @ 120VAC / 24VDC | | **Terminal Type** | PCB Mounting (Through-hole) | | **Seal Type** | Sealed (Washable/Waterproof) | --- ### 2. Internal Components & Construction The relay consists of four primary electronic/mechanical parts: 1. **Electromagnetic Coil:** A copper wire winding that generates a magnetic field when DC current passes through it. 2. **Armature:** A moving metal piece that is pulled toward the coil when energized. 3. **Contacts (1C/SPDT):** * **Common (COM):** The input terminal. * **Normally Closed (NC):** Connected to COM when the relay is off. * **Normally Open (NO):** Connects to COM only when the relay is energized. 4. **Spring Mechanism:** Returns the armature to the default (NC) position once power is removed from the coil. --- ### 3. Circuit Symbol & Connection In a schematic, the WJM-1C4W-R is represented by a coil icon and a switch icon. ```text [Coil +] ----( L )---- [Coil -] /---(NC) (COM)---o \---(NO) ``` --- ### 4. Typical Applications * **Signal Switching:** Routing low-current data or audio signals. * **Microcontroller Isolation:** Allowing a 5V Arduino/ESP32 to control a 110V light bulb safely. * **Telecom Equipment:** Used in switching logic for older telephone exchange interfaces. * **Security Systems:** Triggering alarms or door locks. --- ### 5. Part Number Breakdown (WJM Series) * **WJM:** Series identifier (Miniature Power/Signal Relay). * **1C:** Contact arrangement (1 Form C / SPDT). * **4:** Contact capacity/rating code. * **W:** Sealing type (often indicates "Washable" or "Waterproof" plastic casing). * **R:** RoHS compliant (Lead-free).