Adding notifications to dumb push-button doorbell without neutral wire


I’d like to add a notification system to a dumb push-button doorbell.

This is the rough schematics of my doorbell wiring. As you can see, I only have access to the push-button normally open switch and the live wire. I literally have no idea where the buzzer and the neutral wire are and I cannot further explore since the live wires go inside a concrete wall.

I was thinking to add some Zigbee device to the live wire and monitor the device status, in order to trigger a notification automation when the status changes.

Given my situation, said device should be powered only by the live wire, or via its own battery. Unfortunately I have no way to add an external power supply.

As an alternative I could replace the push button with another device, but only as long as it can still work when HA isn’t available for any reason.

Is it feisible?

I already experimented with a Sonoff ZBMini L2 Extreme, I fiddled with the wires a bit but I quickly gave up, the chime was either always ringing or not ringing at all. I still have it, in case someone can suggest how to properly wire it.

Any help is appreciated!

This ?

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Yes but no way to powerr it at the switch I understand - ? (Also just answering this because I want to watch the conversation!)

You may place a vibration sensor on the buzzer. Ive seen others do that.

I previously disconnected the buzzer and ran the doorbell switch directly to gpio input allowing HA to see it as input. If you go this route, you can use a second smart switch to trigger the bell effectively replacing the doorbell as its switch. You may also get smart siren. I actually had alexa make announcements and had notification on phone with photo.

Currently i dont even have working doorbell and use frigate object detection to “see” when someone at door. This is better since many come to door but don’t ring bell. I do have doorbell for show. They think it works so they still push it. I get phone notification.

I think a simultaneous truck horn and a siren and white powder and a sprinkler should do it!

Do you have access to the two red wires in your diagram, which you label “live?” I assume you have no access to the buzzer itself, although I’d think you’d get some idea where it is just by listening.

Next question: Does that buzzer still need to work when HA is down, or just some alternative?

What I think you’re describing is you have access to the switch loop (two red wires in your diagram), but both the power source and the buzzer itself are inaccessible to you. What I’m wondering is whether you can disconnect the one which runs back to the buzzer and just use the two wires for your own solution.

Reminds me of this version that I was looking at whilst I was researching various options and ideas:

I currently just use a shelly button 1 as the trigger device (did not want to drill into the brick again for a POE based doorbell solution lol) through MQTT that grabs an image from my front door camera which is pushed with a doorbell notification sound play via the usb speaker connected to my host and the doorbell channel in the HA app on my android phone.

description: >-
  Push and Audio notification when Doorbell is active with camera snapshot and
  turn on security monitor for 15min.
  - platform: mqtt
    topic: " shellies/DoorbellButton/input_event/0"
    id: Doorbell Button
  - platform: device
    type: turned_on
    device_id: 0b26817de9a4731d4ff2c37f1e8ddb2f
    entity_id: 865eafd4b42d8852153afa328acccced
    domain: switch
      hours: 0
      minutes: 15
      seconds: 0
    id: NuC Monitor
condition: []
  - choose:
      - conditions:
          - condition: trigger
              - Doorbell Button
          - parallel:
              - service: notify.mobile_app_my_phone
                  title: Doorbell
                  message: Someone is at the door.
                    image: /api/camera_proxy/camera.front_door_front_door
                    channel: doorbell
              - service: switch.turn_on
                data: {}
                  entity_id: switch.power_socket_4
      - conditions:
          - condition: trigger
              - NuC Monitor
          - service: switch.turn_off
            data: {}
              entity_id: switch.switch_04_socket_1
      - conditions:
          - condition: trigger
              - Doorbell Button
          - condition: time
            after: "07:00:00"
            before: "19:00:00"
              - sun
              - mon
              - tue
              - wed
              - thu
              - fri
              - sat
          - service: media_player.play_media
              entity_id: media_player.vlc_telnet
              media_content_id: media-source://media_source/local/doorbell.mp3
              media_content_type: audio/mpeg
              title: doorbell.mp3
              thumbnail: null
              media_class: music
              children_media_class: null
                - {}
                - media_content_type: app
                  media_content_id: media-source://media_source
mode: single

edit: here is another video that may give an idea on how to get it setup with the doorbell the OP has

edit2: updated the included template yamil to include choose functions via triggerID’s since learning about them to optimise it.

I think you’d be better off finding out the location of the existing devices.

You mentioned that you don’t know where the existing buzzer is located - can you not hear it when you press the button? They are typically mounted in a central location such as a hallway.

For the transformer, they are typically located on or near your main electrical breaker panel, although they can be mounted to an existing outlet box, and I’ve sometimes seen them in the attic or high up on the wall of a closet. I had to use a wire tracer to find doorbell wires that had been cut and discarded in a wall cavity where the previous owner had abandoned them after installing a cheap battery operated wireless doorbell.

First of all, I’m deeply sorry for being late. I forgot to turn the notifications on :man_facepalming:

As KruseLuds says, I have no way to power other devices unfortunately.

Unfortunately I don’t know where the buzzer is, as per the scheme above (hope it’s clear enough)


Preferably yes.

Theoretically speaking, yes. Please mind that they are both live wires, and that when the circuit between those two live wires is closed the buzzer will ring.

That was actually my inspiration. I think it’s very convenient.

It’s very nice, but unfortunately I have no way to run the USB cable to power any sort of Arduino/ESP board. I have to power it using the live wires, or something like AAA or coin batteries.

I can hear it and it’s definitely in the entrance room, but I can’t pinpoint its exact location.

I tried, but the entrance room is very small (it’s like a western-style genkan, there’s just enough room to leave coats and shoes), and there is electrical stuff in every corner since per my country electrical code the main breaker box and the main solenoid valves for the DHW and heating must be located there.

You could get the power from it from where the breaker box is, the reader and the board can sit anywhere on the line between the bell and the box as all it’s doing is detecting the change in the current for these types of older doorbells when the button is pressed.

I designed something similar to this a couple of years ago. I never built it, but if you are a tinkerer this might give you an idea. Know what you are working with by measuring the voltage across the button. In this project the “live” was 24VAC. (I suspect that this is similar to how Ring doorbells work).

It works like this. At rest, the live and switched live feed the rectifier bridge. The output of the bridge goes into a 3.3V Low Dropout Regulator to power the ESP 8266-01 chip. The capacitors are there to keep the 3.3V level during the brief time the relay is energized. (I was planning to use a super-capacitor). When the button is pressed, the relay would be energized for a brief time (5 ms), shorting the live and switched-live lines, ringing the buzzer. The code in the ESP would drop the relay reconnecting the power into the rectifier bridge.

If you do all the code in ESPHome, you could easily write an automation to respond to the button press. Then you can have ESPHome turn a light on, sound a loud Klaxon bell or anything you want to use instead of the original buzzer.

Put the whole works inside a plastic utility box. You can use a toggle bolt to hold it to the wall using the hole the wires come out through. When you move to another home you can easily remove everything and put the original button back where it came from.

Not feasible. it’s all brick and mortar here, with cable conduits sunk deep inside the bricks (I think it’s called a “chase”?). No way to know for sure where the conduits go nor to add a new wire.

I’ve already tried to run a fish tape along the live wires of the doorbell button to see if I can hear or feel where that conduit goes, to no avail.

I designed something similar to this a couple of years ago.

I thought about a Graetz bridge before, but those can’t work without a neutral wire and your scheme seems to confirm that, am I right? Sorry for the dumb question, I’m just an amateur.

Yea without having any access to the cables you won’t be able to install a reader to detect changes in the voltage when the button is pressed and without a place to power the esp running the code to talk to your HA install you are limited to replacing batteries or having a decently sized power bank connected to it to power it to recharge every so often.

All that said one thing that comes to mind as another work around is to use a leak sensor like the Aqara Water Leak Sensor since it can be used with a pressure sensor to make a bed presence sensor with the easy access to the contacts; which in this case would sit between the bell button out and the cable going into the chime, so when the doorbell button is pressed it closes to circuit to trigger the sensor to send the signal.

That idea comes from so just adjust from a bed pressure pad to a doorbell mode instead.

The button is mounted on an recessed electrical box, which is empty beside the two wires. There’s plenty of space, about 80x60x50 millimeters. For reference, these are the outer dimensions of the box; if the link doesn’t work, google “scatola incasso 503”.

I can post some photos if needed.

use a leak sensor like the Aqara Water Leak Sensor

This is a great idea! I’ll give it a try, thanks!

Yup that should fit one in, just keep an eye on the battery life and have an alert setup to let you know when you need to replace the battery, if you can try have easy access to the sensor for when you need to replace its battery.