4-Wire Intercom -- Wiring Uni to detect doorbell tone signal.

JerryD11 · Jul 13th 2021

Hi All--

I'm new to the forum and to Shelly. I just ordered a Uni and will have it in a couple of days. My intercom system is an Alpha IS407C (photo, wiring diagram and specs attached).

It's 16V,
4-wire (1, 2, 3, X)
with Talk, Listen and Door buttons,
- the latter of which releases the magnetic lock in my lobby (a buzzer).
- The doorbell signal travels over the X wire with 1 as ground and the door release button connects wires 2 & 3.

I'm much more of a software and household DIY guy ... Electronics circuitry is a bit intimidating to me. If anyone would be so kind as to offer some advice as to how I might go about wiring the Uni into my system and advise what type of power supply I should purchase I will be forever grateful! Thanks so much.

JerryD11 · Jul 15th 2021

Perhaps somebody might be able to give me an idea of which Uni wires I need to be able to detect a tone signal from a doorbell ring please?

66er · Jul 15th 2021

Hi and welcome to the forum.

Maybe funkenwerner can help.

funkenwerner · Jul 15th 2021

hmmm you would have to measure what voltage in DC V arrives at the loudspeaker when it rings, then you can think about whether something would be feasible, the first idea would be Shelly Uni, but users DIYROLLY could say more about that

JerryD11 · Jul 15th 2021

Thank you. I'd appreciate any advice you're able to offer. It's difficult since I live alone and can't go out to ring the bell and be inside simultaneously to measure. I'm also really baffled by the multimeter to be quite honest. Particularly the dial with 30-40 measurement settings which kind of implies guesswork is involved on my part and I'm clueless how I should be able to guess at the very thing I'm trying to find out. I'm sure that's probably way off-base and a really stupid presumption on my part. I'm good with logic and building - my own ideas especially but I can follow assembly instructions as long as the parts are clear and I know where it needs to wind up. I've even pulled wires and installed new outlets and lights, built and installed a MagicMirror/medicine cabinet and linear-actuatored my toilet so Alexa & Home Assistant can flush it.

Perhaps this will be clarifying? There used to be a relay board made by Tektone that's now discontinued which was specifically for this purpose and worked with my system & model. It detected the doorbell signal and flipped a relay to be able to connect external audio devices and LEDs for hearing impaired folks. The specs for it are attached. Thank you!