5V 4-Channel Relay Module

Overview

The **5V 4-Channel Relay Module** is a commonly used relay board that allows low-voltage devices like microcontrollers (e.g., Arduino, Raspberry Pi, ESP32) to control high-voltage loads such as lights, fans, and motors. Each of the 4 relays can switch up to 250V AC or 30V DC at 10A.

Specifications

• Operating Voltage: 5V DC
• Trigger Voltage: 3.3V to 5V
• Relay Capacity: 250V AC at 10A or 30V DC at 10A
• Number of Relays: 4
• Trigger Type: Active LOW
• Isolation: Optocoupler for each relay
• LED Indicators: Indicates the state of each relay
• Dimensions: Approximately 72mm x 50mm

Pinout

Working Principle

The module uses a low-level control signal (3.3V to 5V) to activate the relays. Each relay is connected to an optocoupler for electrical isolation, ensuring the microcontroller is protected from high voltages. When a control signal (LOW) is sent to an input pin (e.g., IN1), the corresponding relay activates, allowing current to flow through the load connected to its Normally Open (NO) terminal.

Relay Terminals

• **COM**: Common terminal
• **NO (Normally Open)**: Connected to COM when the relay is activated
• **NC (Normally Closed)**: Connected to COM when the relay is not activated

Applications

• Home automation (control lights, fans, etc.)
• Industrial control systems
• Robotics
• IoT projects
• Smart irrigation systems