Relay Module
An electrically operated switch that lets your Arduino control high-voltage and high-current devices like lamps, motors, and pumps.
Overview
A relay is an electromagnetic switch controlled by a low-power signal from your Arduino. It allows you to safely switch high-voltage AC or high-current DC loads — things the Arduino could never power directly. The relay module includes the relay, a flyback diode, an optocoupler for isolation, and screw terminals for your load.
ArduinoStudio supports both Normally Open (NO) and Normally Closed (NC) wiring configurations. When the relay is activated, the COM (common) terminal connects to NO; when deactivated, COM connects to NC.
Specifications
| Parameter | Value |
|---|---|
| Coil Voltage | 5V DC |
| Max AC Load | 10A / 250VAC |
| Max DC Load | 10A / 30VDC |
| Trigger Level | Active LOW (most modules) |
| Isolation | Optocoupler isolated |
Wiring Guide
Control Side (Low Voltage)
| Relay Pin | Arduino Pin |
|---|---|
| VCC | 5V |
| GND | GND |
| IN | Any digital pin |
Load Side (High Voltage)
Connect your device to the screw terminals:
- COM — Common terminal (always connect your power source here)
- NO — Normally Open (device OFF by default, ON when relay activates)
- NC — Normally Closed (device ON by default, OFF when relay activates)
Safety Warning
When switching mains voltage (110/220V AC), always use proper insulation, keep connections inside an enclosure, and never exceed the relay's rated current. If you're unsure about working with mains electricity, consult a qualified electrician.
Usage in ArduinoStudio
Drag the Relay component onto the canvas, assign a digital pin, and use the on / off / toggle actions in your sequence to control it. The relay pairs well with sensors — for example, turn on a lamp when a motion sensor triggers.