@gerard33
Please note that the wiring diagram is incorrect.
I on Shelly must be connected to + from the AC-DC transformer
O on Shelly must be connected to + on the doorbell chime
- on the doorbell chime must be connected to - on the DC side of the transformer
Please see figure 2 of the Shelly 1 manual https://shelly.cloud/documents/user_guide/shelly_1.pdf
Please mind the polarity. Figure 2 in the manual: https://shelly.cloud/documents/user_guide/shelly_1.pdf
- goes on N and - goes on L.
Yes, Shelly Uni will work with 12VAC in figure 4B. Shelly 1 will require 12VDC, but please mind the requirements of your doorbell chime.
Hi @gerard33,
Love this project!
I’ve tested the same setup, but I struggle with the fact that often it takes over a minute for Home Assistant to notice that the state has changed. I never had this kind of latency in my old setup. I’ve moved house, and changed my access point to TP-link Deco (in AP mode). Could this mean I have networking issues?
When I toggle lights in HASSIO the change is always immediate. But the state of the Shellies is communicated much slower. This leads me to believe that Shelly or HASSIO might be the reason why I get trouble?
A minute is a pretty long time for someone to hold the doorbell button…
Good to hear you like the project 
That minute delay is way too long indeed. There is certainly something wrong somewhere.
I get an instant reaction when the doorbell is pressed.
What integration are you using for the Shelly’s? Is it MQTT, Shelly4Hass or the standard HA integration?
Maybe you can switch integrations to see if that fixes the issue?
Though I understand your remark (one red wire for + and and blue wire for - from the transformer makes sense), the wiring diagram is correct and I can assure you that it’s working fine for me 
The wiring in my house from the transformer to the button and chime was originally with 2 red wires connected to the transformer. Seems to be a normal solution, see the diagram below.
Guess it’s just a matter of taste how to wire it so the circuit get’s closed when pressing the button.
@gerard33 Thanks for the tips!
Your comment made me think. I have also set up MQTT to start working with Zigbee.
Will see if I can sort it out by switching integrations. 
With ShellyforHass I have the notifications and changes in milliseconds.
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I’ve got a new Shelly 1 and the temperature is good for now with the same adapter.
That’s good to hear. Probably something wrong with your previous Shelly then.
I just set this up and it works like a charm. Thank you for figuring this one out!
When I set it up I was a bit surprised that my doorbell just kept on going which was a bit confusing.
I solved this by using the auto off function in the Shelly.
On your Shelly, choose button type ACTIVATION SWITCH and then enter the desired auto off time in the TIMER settings.
I’m preparing for the installation and have a question. On the connection diagram, the 2 red wires going out the 8v tranformer are connected to a seperate connector?
At the moment my transformer has 1red and 1 blue wire connected (see image)!
20210206_140445|273x500
Where you already able to connect it?
Otherwise you can connect the cables according to how they are connected to your transformer. See this post 34 for more details. You should be able to use the way Rubueno describes the wiring.
I connected it all. But I think i’m missing something. Shelly1 is visible in hass, when I switch the doorbell in hass the chime rings and everthing works but when I press the real doorbell the chime rings but hass does not detect it (no state change in de switch or sensor).
I used the native shelly integrations and also the shellyforhass and both the same issue. I dont think it is my wiring what do you think?
I tried an alternative option, because I was reading that other people were having the same issues all related to firmware versions. I installed the mqtt broker and Shellies Discovery Script. This is working fine and fast response when the doorbell is pushed.
A cool dumb doorbell made smart! Thanks!
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Will this work with sonoff mini?
Good to see it works now, although strange that it wasn’t working with the native and the Shelly4Hass integration.
See this post.
I have put some extra information on the bottom of the opening post for the scenario when the button of the doorbell is only pressed for a very short period and the chime rang but HA wasn’t triggered.
any chance you have a guide for sonoff mini instead? I believe sonoff mini has pulse mode which allows it to trigger the bell once.
@gerard33 there is one thing I do not understand. My trafo expects 230V and it needs two wires as input and two as output. I only see one in and one out in the schema? I would expect something like below.
Also if shelly gets 12V as input it will also output 12V to the trafo isn’t that an issue?
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