You need a power source, a way to level convert the driver pins, and some protection in case something goes wrong with the circuit ... he was able to control the relay using 3.3V, 5V, or 12V.

For that reason, [Hulk] designed a simple relay module in order to cut the amount of time he spends implementing this solution in his various other projects. While driving a relay with a ...

The system allows users to wirelessly control multiple AC appliances like lights and fans through an interactive web interface ...