Yeah, there's a setting for that under Timers > Auto off.
Take a look here: Settings on the Shelly Homepage
Tasmota has something similar via console, with the PulseTime 20 (i.e. 2 seconds) command: https://nerdiy.de/en/tasmota-nac…ais-einstellen/
Glad that you got it to work, pretty satisfying! 
Hi, yeah. You can use each of the two outputs for that; in the Shelly Uni the ESP8266 Wi-Fi chip controls two TLP172GM photorelays that can be open and closed, "shorting" both leads and closing any circuit you attach it to.
Check out this thread for some diagrams and ideas, should be more or less the same: Retrofiting a 5-wire (4+N) 12 VAC analog intercom/entryphone with a Shelly UNI. Tegui Horizon N. Tasmota. Diagram and help.
The only thing you need to keep in mind is the type of load these outputs support, the current going through it can't surpass 100 milliamps, which is enough for smaller signals but not for activating something big and mechanical like some AC electric door strike. So it may not do anything, not getting enough current through. To do that you will need to use one of the Shelly Uni outputs to control a mechanical or solid-state relay, acting like a middleman between the two.
This page is interesting: https://toshiba.semicon-storage.com/us/semiconduct…photorelay.html
There are small preassembled relay board kits out there, but check out the supported input voltage of the relay. Some of them only work at 12v AC, and keep in mind that SSRs are usually chunky and you can use them as-is, but they can generally only switch either AC or DC load, not both.
Mechanical ones don't care, but you can hear them click.
In some cases, if you have something like a regulated v12 DC power line to feed your project you might save time by using a different all-in-one ESP board with an included relay. They might be chunkier than a Shelly Uni + some SSR tucked into some wall hole, though.
And it won't have the Shelly firmware, which is user friendly and lets you install alternative firmwares like Tasmota over the air, from your computer.
Thanks a lot for the detailed response! I will look into what you mentioned in depth. But that helps me a lot.
Yeah, I was a bit weary about breaking or degrading the installation, that's why I wanted a second (or third) opinion from someone who actually knows what they are doing. I was wondering if there's a way of powering it from one of the analog microphone/speaker terminals by filtering noise, or from the door opener without triggering the opening function itself. Reminding me a bit of the no-neutral WiFi switches that use a parasitic voltage device. Not that I would be able to come up with something as fancy right now.
But yeah, no other power cables seem to go up here from the entrance panel. And when you look at the E-14 diagram I posted above, four of the cables seem to be shared by everyone, then there's an extra one per apartment for the buzzer/bell. As you said there's only continuity on that one when the entrance switch is pressed, makes perfect sense. No need for anything else, from their point of view.
I'll take another good look at the whole thing. Any comments and suggestions are welcome.
Updated the post with a handy diagram of what I aim to do. Let me know what you think.
Hi, I have a classic analog intercom/entryphone system based on a Tegui Horizon N that I thought would be cool to domotize, so that I can actuate the door-opening switch remotely and get notified via Telegram notifications when the 12 VAC buzzer rings.
I have been able to switch my Shelly UNI to Tasmota using this intermediate OTA firmware, knowing that I can always go back to the original Shelly firmware with this. Tasmota supports the direct Telegram message integration when enabled in custom builds. Super neat.
So everything works from the software-side when hooked to a 12 VDC wall wart adapter, great. Now the fun part begins.
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Here's the official layout for the five terminals:
Here is what I aim to do, roughly:
2021-06-17-tegui-shelly-uni-diagram-scheme-d.png
(Image mirror: https://i.postimg.cc/ty8knnpn/imagen.png)
In the official diagram it says that the electric door lock is rated for 12 VAC 880 mA +- 5%.
Reference PDFs: Official Tegui E-14 installation diagram, Shelly pinout.
I measured the voltage of the terminals with a multimeter. Here's what I found:
2, 3: 13 VAC
3, 4: 13.23 VAC
5, 4: 4.91 VDC
5, 3: 13.26 VAC 50 Hz
4, 2: 5.~ VDC
5, 2: 0 VAC
1, 2: 11.20 VAC while buzzing, zero otherwise.
3, 2: If I bridge these for a few seconds with the disconnected multimeter leads the electric door lock opens as normal. That probably means that I don't have to disconnect the speaker/microphone lines beforehand, reducing complexity.
Attaching the Shelly UNI outputs directly to 2, 3 does not work, I can hear it buzzing through the earpiece when the Shelly's TLP172GM is running but the electric door lock doesn't budge, so I'm thinking I'll be needing a small external relay that can handle more than 100 mA and still fits inside.
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Now, the two big questions. Can I feed the Shelly UNI directly without adding noise to the line/interfering with/damaging the speaker and microphone? Do I need an external power supply? It would be neat to have it all in a self-contained way. But I guess I can always go for the AC to 12 DC adapter route if nothing pans out. If I use external power without matching reference voltage for IN_1 will I be risking destroying the Shelly UNI? Will that still work?
What's the best avenue for an external relay that fits inside and can be actuated by the Shelly UNI? Do I need to add flyback diodes to protect it, any premade kits out there I can use?
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While I have a very rudimentary knowledge of electronics I can handle the software side just fine. This is a learning experience for me, hopefully someone can give me some pointers. I don't want to break anything. Please be kind and thanks in advance.
PS: Maybe the documentation helps other people thinking about doing something similar with their own analog intercoms. The order of the terminals may be different, but from what I've seen on the Internet they are all pretty similar.
