Arduino Relay Module Control
An Arduino relay interface lets a low-current microcontroller output switch a separate load circuit. In this example, the Arduino output drives a 5 V relay module and the relay contact switches a 12 V lamp supply. Keeping the load supply separate makes the control and load roles clear, while the relay contact provides the switching boundary. A diode across a bare DC relay coil reduces the turn-off voltage spike; ready-made relay modules often include this protection already. Do not use a breadboard relay circuit for mains wiring. For larger DC loads, confirm the contact rating, wire gauge, fuse, and the need for a flyback diode across the load itself.
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Scenario
Arduino-controlled isolated load
Key decisions
- Logic: Keep the Arduino on its 5 V control supply.
- Switching: Use relay contacts for the separate 12 V load.
- Protection: Suppress the relay coil voltage spike.
When to reuse this
Use for an Arduino project that switches a low-voltage DC load through a relay.
Frequently asked questions
Why use a relay with an Arduino?
Does a relay module need a diode?
Can this switch mains voltage?
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