I'm starting a new project (for personal use), I want to build a circuit that will enable me to control a lightbulb through my phone. I want to use it as an additional lighting at my living room.

after researching online, I have a general idea about how I want to build the system. The block diagram is depicted bellow:

enter image description here

Links to the parts I'm planning to use:

  • Arduino Uno + wifi module + adequate power supply
  • relay
  • light bulb socket - I'm still not sure it'll be the exact socket (since I still haven't chose the light bulb itself, but the only thing that will change is the type of the light bulb, the cable with the plug will look the same)

I have a few things I'm not sure about:

  1. Can I connect the relay directly to the wifi board? In all the tutorials I've watched, such as this one, that was exactly what they did, but I read in some places that it's dangerous. If it is, how should I connect the relay and the board?
  2. The Wifi board I'm planning to use is Arduino Uno with wifi module, I chose this one since I already have it. Are there any better alternatives? I'd like to hear your opinion about which wifi board to choose for this project.
  3. I would be happy to hear your opinion about the whole planning, please note that I'm a beginner, so I'm looking for something relatively simple, but not too simple (such as buying a wifi controled light bulb from amazon). any opinion and advice will be highly appreciated!

Thank you.

  • \$\begingroup\$ this isn't a great project for beginners, buy some sonoff modules before you burn something down. \$\endgroup\$
    – dandavis
    Sep 22, 2020 at 20:59
  • \$\begingroup\$ "Can I connect the relay directly to the wifi board?" this question makes me think that even after watching the video you still don't really understand what a relay is. A relay is used to isolate to circuits. Typically a low power circuit is used to control a high power circuit. \$\endgroup\$
    – JoeyB
    Sep 22, 2020 at 22:09

1 Answer 1


There are 5V relays modules that work well with 5V arduinos (like the one you plan to use). These don't actually connect the relays directly to the arduino, however, and simply have a mosfet built in to the board and are powered over a 5V VCC pin that is separate from the 5V logic pin that goes to the arduino.

If I were to tackle this project today, I'd use ESP32 rather than arduino (due to cost) and "3V Relay Module" (esp32 logic is 3V). ESP32 can be programmed from the Arduino IDE :)


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