4-Channel 5V Relay Module (Arduino-Compatible)

Overview

This four-channel relay board lets a microcontroller switch loads it cannot drive directly, such as lamps, fans, pumps, solenoid valves and motors. Each relay is controlled from one digital pin and has an LED that shows when it is energised.

Every channel brings out COM, NO (normally open) and NC (normally closed) on screw terminals, so a load can be switched on or off when the relay operates.

Key Features

• 4 independent relay channels
• 5 V DC relay coils
• Contacts rated 10 A at 250 V AC / 30 V DC
• COM, NO and NC screw terminals on each channel
• Status LED per channel

Typical Applications

• Home automation and smart switch projects
• Switching pumps, fans, lamps and solenoid valves
• Irrigation, aquarium and greenhouse controllers
• Industrial and lab prototyping

Compatibility

Controlled from a digital pin of a 5 V board such as an Arduino Uno or Mega. With 3.3 V boards such as the ESP32 or Raspberry Pi, check that the inputs switch reliably from a 3.3 V signal. The relay coils need a 5 V supply that can deliver the coil current of all active channels.

Important Notes / Safety

• Mains voltage is dangerous. Keep 230 V wiring isolated, enclosed and properly fused, and have it checked by a qualified person.
• Do not run motors or heaters near the 10 A limit continuously; leave a safety margin.
• When powering several relays, supply 5 V from a separate source rather than the microcontroller's own regulator.