Making a dumb doorbell smart

I made my dumb doorbell smart with a NodeMCU, a few resistors, a transistor, an LED, and a 5V relay module. It’s set up to publish to a MQTT topic when the doorbell rings and because the microcontroller is firing the relay to ring the bell it can also be disabled (huge for me because my dogs go nuts when the doorbell rings). It uses an off-the-shelf button that’s modified slightly and the doorbell transformer and bell are directly off-the-shelf.

Let me know if I should add more information or if you’ve got any questions.


I made a video demonstrating it

Links for the stuff I used in the doobly-doo

Thanks for sharing :slight_smile:

This is great!

If possible, could you please post the model that you used for the buck converter enclosure?
And if you are able to update your schematics with the Wemos stuff, that would be greatly appreciated!!


I did the same, but with much less work. I shoved the innards of a open close sensor that is normally used on windows or doors inside of the dumb doorbell’s ring box. It detects the magnetic field that is created when somebody rings the doorbell. I also disabled the audible ring by simply removing the metal chimes from the ring box on the wall. Now my Home Assistant app will alert me when somebody rings the doorbell. In my case, it actually says “there’s somebody at the door.” My dog doesn’t know English, so he doesn’t know to go crazy and start barking. He just thinks it’s another one of my home assistant speech Notifications. LOL.


Thank you for sharing this, it preety cool. But if possible can you describe / diagram the ac-dc conversion to power up the nodemcu as well as then using the relay to fir the doorbell? I saw your page but it mostly the nodemcu side and not much on how ac-dc conversion and how relay connects to other side of solenoid / bell

This is my understanding so far

  1. You take 2 wires coming from transformer to your bell (terminal and Front door) and using buck converter to convert 16v AC to 5v DC
  2. Then you add one more wire (possibly before 1 above) and feed to relay to continue using that as ac circuit?

Thanks for sharing this.

The buck converter just taps the low voltage AC going to the existing doorbell transformer. The transformer stays connected as it’s always been. The WeMos just takes the place of the doorbell button and the doorbell button was converted to DC vs the AC it was expecting hence LED VS grain of wheat lamp.