5V Relay Module — Opto-Isolated, 1-Channel

The safe, simple way to let a small microcontroller control something big. A relay module lets 3.3V or 5V logic switch real household-voltage loads, a lamp, a fan, a heater, without ever letting your controller's delicate GPIO pins touch dangerous voltage directly.

Opto-isolation is the detail that matters here: an optical barrier physically separates your control circuit from the switched load circuit, so a fault on the high-voltage side cannot feed back and fry your controller.

• 5V logic trigger, opto-isolated for real electrical safety
• Switches high-current or high-voltage loads from a simple digital signal
• Works with high or low trigger logic, compatible with virtually any controller

The switching component behind our Digital Thermostat Demo, where it is the difference between a build that just displays a temperature and one that actually does something about it.