Thanks for the tip about the contactor, I see how that could work with the Shelly.
However, I have also been thinking about your comment on using the BTicino actors. I have an actor with a free channel right next to the bell power supply. And when I think about it, the only thing I’d need to add is the relatively inexpensive 3477 contacts interface in the breaker box, to integrate the conventional switch.
Then I’d have the complete bell system in BTicino, which I think is the most reliable part of our home automation, and can still do fancy, non-essential processing of the bell signal in openHAB via the BTicino binding.
What do you think?
I guess it should, but I tried it on the output of the power supply and did not get any reading, but maybe I have been doing something wrong. Need to get a bit more familiar with how those multimeters work.
well here you are right that would be more reliable than a Shelly for sure. And now i also see the picture you said next to the transfo you have an empty contact and those i am sure they support 230v at 2 amps for the contact.
So go for it you can finish the project this evening just put the ding dong on the bticino and then the button on the Shelly uni for now and then you have time buy this instead of what you suggested https://catalogue.bticino.com/BTI-F428-EN
Thanks, I was not aware of the F428, and of course it makes more sense for the breaker box. Already ordered it and it should be here in a couple of days. I’ll post an update once I have it and in the meantime I will work on the Sonos part of the solution.
While waiting for the F428, I am still thinking about the failed Shelly setup and for my own learning would like to understand better why it did not work.
Particularly the wiring shown below. With that, the Shelly always showed the switch input IN1 as ON. Only when I removed the blue connection from power supply 3 to the bell the Shelly detected the state of the button correctly.
Is there really current flowing through the bell that activates the IN1, or is there another explanation for this behavior?
So I put the multimeter on V ~ 200, measured power supply 1 to Shelly IN1 and it gives me a reading of about 15. If I put the leads directly on the power supply 1 and 3 it also gives me a reading of about 15. Not sure what that means, but it seems the current is flowing pretty unfiltered through the bell?
Your bell/chime could be a big inductor (mine is). When current goes through it, a magnetic field is created and the solenoid moves and hits the chime. If you measure the voltage on the other end of the inductor without the button pressed, you’ll see the same as the input side. Extremely little current is flowing - only that which goes through your test equipment and you’ll see virtually no change from input side to output side in this case. Only when the button is pressed will substantial current flow which will have enough magnetic field to move the solenoid.
When the button is open (not pressed) you’ll certainly see IN1 at the same voltage as pin 3 of your power supply. When the button is pressed, the voltage will be the same as pin 1.
Thanks! The Shelly Plus 1 would have been my first choice, just used one for our entrance gates. But both the original Shelly 1 and the Shelly Plus 1 can only run on 12V DC, not AC, so that would not work, would it?
Anyway, waiting for the BTicino F428 now, I hope with that it will work. The BTicino setup is more independent of the 12V AC, the devices get powered via the bus, the button is taken out of the 12V AC circuit and the actuator only needs to switch that circuit:
That’s an easy fix. Just add a diode, or a rectifier bridge + capacitor, but it’s another extra little bit, so it’s messy. If your bticino would work, then the problem is solved.
The Shelly input is likely high impedance, so this makes sense. You have a low impedance through the bell and a high impedance at the Shelly input. So almost no voltage drop, and thus the Shelly triggers on it.
Integration with openHAB is also already in place and the doorbell now triggers mobile push notifications as well as sound and voice notification via Sonos and the Echo Dots.
I documented the whole setup on my blog, including the failed attempts with the Shelly Uni:
Thanks again for everyone’s help here, I really appreciate it!
Hi there,
Just today found that post, so my response is probably far too late. I would just have added a small power converter 12v AC to 3.3V DC in parallel to the bell. This would provide the power to an ESP01 (e.g. with tasmota,) which comes up, when the bell rings, because it gets power . It sends an online status via Mqtt or other possibilities to OpenHAB - that’s it.
Cheers
Wow, funny to read how different people come up with different solutions that I would never think off.
Reading the initial diagram I think I would put and ESP01 in the circuit box (location 1). When rectified and using a step down convert it will power the ESP01 easy. To get input I would place a small resistor (so the bell keeps ringing) in the blue or black line to location 2/3 (the button and bell). In normal conditions it will have a 0V AC. When ringing a small AC voltage. Of course for an ESP you’ll need to convert the AC trigger to 3.3V DC. An opamp will do that job. But of course, my solution requires some knowledge of electronics and ESP01
Input Signal 13V ac goes thru bridge rectifier
Get 7 V dc , which is linked to an opto coupler via 10 kOhm . Second side 3.3 V via 330 Ohm on opto coupler to pio 27 with pull down resistor.
The condensator in the bridge rectifier works also as a signal extension.
In total 5€ for the layer.
