Looking for ideas on how to integrate door bell

Thanks for all your responses!

Good point, you are right, it is 12V AC, not DC. I added this info to the diagram in my original post.

Most Shelly devices run only on low-voltage DC. The only one I could find that would run off 12V AC is the Shelly Uni.

The Shelly Uni also has two switch inputs, do you think this could also work with a Shelly Uni? And would it close the circuit so that the conventional bell still rings?

Sorry if those questions sound stupid, I am a software engineer and as of yet my knowledge of electrical installations is still very limited.

Edit:

So, from those comments I understand that the bell would likely not work anymore and I‘d have to remove it from the circuit?

Rewiring would be difficult, the locations are pretty far apart, with the power supply in a breaker box in the cellar, the bell next to our house entrance door and the button at the garden entrance door.

Removing the bell sounds like a good solution, though I would have preferred to leave the conventional solution in place, in case openHAB doesn‘t work for some reason.

As JimT points out probably not.
I‘d replace the power supply and go for Shelly i3 or i4.
As I wrote in worst case you need to remove the bell and shorten the wires (directly connect them) and use an android tablet for sound output. You might have a wall mounted tablet anyway…

why not use a 12 vac relay in paralel with the dingdong to give you a dry contact for the shelly
something like this so you get an inpulse
https://sa.rsdelivers.com/product/finder/382100120060/finder-din-rail-multi-function-timer-relay-12v-ac/dc-spdt-01-s-6h/6667937#_

OK, understand, thanks. We have Sonos speakers all over the house and I’d like to use those for sound output. If that works reliably, then foregoing the existing bell would be OK.

Today I’ll have a bit of a closer look at all the wiring. For some reason, there is two bell power supplies in our breaker box, both giving a 12V AC output. One of them is connected to a breaker labelled “bell”, so I assume that is the one I’d need to hook into, but not 100% sure. No idea what the other power supply is for. The wiring in the breaker box is pretty messy and it is hard to follow the wires and figure out where they go.

To be honest, I have no idea what that means. If that would be installed where the bell (dingdong) is, then the main issue is that I only have the switched 12V AC there, no permanent power to drive a Shelly.

are you sure the dingdong goes to the button like your diagram? i highly doubt that. Most likely your cable from dingdong goest to your electrical panel. Double check because that type of wiring means your house was build back in the 60.
Also a simple alternative is then the Shelly uni

The house is relatively new, it was built in 2008. The breaker box with the wiring for the bell circuit is in the cellar, where I found the power supply. The box with the dingdong is next to the house’s entrance door, and there is only two wires going there, the blue and black one shown in the diagram. I have not opened up the button yet, will do that today if snow stops falling, it is outside at our garden’s entrance door.

I am not sure if the cable from the button goes to a breaker box first before then going to the dingdong, or directly. The cabling in the breaker box is so messy that I’d never find it anyway, I am afraid.

Here is a photo of the power supply:

And here one of the dingdong. I also removed the dingdong from the wall, but behind it there is also only the two cables you can see on the photo plus an unused yellow-green ground cable. The two white cables go to a battery-driven radio device that triggers a receiver on the first floor. This part I would like to get rid of and replace with the new openHAB-based Sonos solution.

new build Europe style. Most electrician take a 3x 1.5 from button to panel and a 3x1.5 from ding dong to panel and do the connexions there. just follow the black and brown cable from the transfo inside the panel and you will find two separate cables with a wago connected

Here’s another idea: add a 12V AC relay in parallel to your dingdong, something like this and use the output to pull an input pin to the ground for your shelly. You’d need to find a power source for the shelly near your dingdong.

Another idea: Use the 12V AC to power some sort of electromagnet which will trigger a wireless “contact sensor”. I have a few xiaomi aqara door/window contact sensors. They’re battery powered and last more than a year (I haven’t had to replace mine in 2+ years yet). They communicate via Zigbee.

Most electromagnets you could buy are probably overkill for activating the reed switch in the contact sensor, so you could just build one by winding some wires around a piece of metal like you do in school physics experiment. You might need to add a diode, something like 1N4001 would probably work, so the magnet remains in one direction.

So it would look something like this?

Unfortunately there is no power source anywhere close to the dingdong.

I wanted to avoid something battery-powered and adding another radio technology like Zigbee. We already have a battery-powered radio transmitter there, which as a receiver on the first floor. I could connect a Shelly to that receiver somehow I guess, but I would have preferred to simplify the solution and remove that old solution.

Let’s see, maybe if the wiring actually goes like @stamate_viorel suggests via the breaker box there may be an easy solution, because then I’d have the power to drive a Shelly and the switched circuit in one place.

I’ll open up the breaker box again today and try to figure this out …

For the sake of humanity, I really hope this were true. It’s the only logical and sane way to do it.

OK, it seems I am lucky and @stamate_viorel is right, it looks like all the cables come together in the breaker box. Here is an update with what I found in the breaker box.

The red/black cables leaves the breaker box with the cables I know to open up the garden entrance door, so I am assuming they lead to the button next to the garden entrance door. The black/blue cable leaves the breaker box together with a yellow-green ground cable, of which there is an unused ending up at the dingdong, so again I assume they lead to the dingdong.

So I’d use a Shelly Uni (one of which lies unused in one of my drawers). It can run of the 12V AC and has a sensor/switch input that as far as I understand I could use to detect if the button is pressed. I don’t have to exchange any components and the conventional dingdong would keep working.

I think the appropriate wiring would then look like this. The wire colors are shown as they come out of the Shelly.

This would be as per Shelly’s wiring example in the documentation for 12V AC and a switch input:

What do you guys think, could that work?

go for it

now that you have access to the 2 cables of the bell, I would connect them to Shelly’s output.
It is uncertain that the bell works this way.

If you wire the chime to the shelly output probably through a 12v relay then you can use openhab rules and allow for other smart bell capabilities like do no disturb mode.

Why may it not work this way?

I am asking because it does not really work and I am not sure why. Currently I get a permanent ON signal on the channel. When I disconnect the orange cable from the Uni, it goes OFF, but when I reconnect it, it goes ON again.

There may be an unrelated explanation, we had issues with this button before when it was freezing. Currently when I press it, it returns very slowly or I have to manually push it back into its original position. When I press it again, the bell rings again. But here is what is weird, currently, the bell doesn’t make a “dingdong” sound but only “dong”. So I am not sure if a frozen/moist button could lead to a situation where maybe the bell gets halfway triggered, but there is a constant current flow that is enough to keep the Shelly in its ON status.

Or, there is still something fundamentally wrong in my understanding of the system or the wiring. :frowning:

Will try to figure this out tomorrow and also will try to disconnect the bell to see if this causes the issue. I’d have preferred to keep the bell connected conventionally, as kind of backup, but of course connecting it to the Shelly’s output also has its advantages.

What would that 12v relay be used for? I think the Shelly Uni outputs should work without any additional device?

Jim has explained this in the beginning

You can go ahead without a relay. Shelly Uni’s potential-free outputs can
switch up to 36VAC.

Are you referring to this?

So basically, there is a little bit of current flowing through the bell, enough to keep the input of the Shelly activated?

Yes, I was referring to this. And no, your Shelly is always activated (supplied with power). If you close the switch, Shelly gets triggered and for the short time while the switch is closed the door bell is provided with power. Jim said that the power will not be enough to ring the bell.

Hmmm, then this does not seem to be related to my current issue of the input always being ON. Will try to figure it out tomorrow, now it is time to go to bed.