SHELLY UNI DOORBELL - BPT E 220

George Kolitsas

Hello everyone! I am struggling the last two weeks with the intercom BPT E/220. Unfortunately everything I have tried where in vain. I am attaching a picture of the intercom and the cables connected to it.

What I know so far are the following:

Intercom provides 11.5V DC between connections 2 - 1 and 2 - 3. There is not enough power to power up a shelly uni or even a sonoff 5V with step down.
Door is unlocked if a connection with cable 1 and 2 is established
When the door bell is pressed 1.2V is noticed between cables 1 - 4 and 3 - 4

I am able to power shelly uni with external power supply and unlock the door. But how would I be able to detect the 1.2V when the doorbell button is pressed?

thgoebel

Due to the fact you’ve not only a simple doorbell but a door intercom, I would recommend to tap the signal „doorbell rings“ from the loudspeaker of the intercom station. An how-to is to find here (unfortunately in German language):

Thema

Shelly mit Geräuscherkennung (Klingelsignal bei Busanlagen)

In dem Beitrag "Uni mit Haustelefon, keine Klingel/Gong sondern Lautsprecher" wurde gezeigt, wie eine Baugruppe ("Analog Sound Sensor") von Makershop mit einem Shelly UNI gekoppelt werden kann. Nachteilig dabei ist, daß die Baugruppe mit 4 bis 6V DC versorgt werden muß. Ein anderer Nachteil ist, daß es falsch positive Meldungen geben kann, weil das Soundmodul durch spielende Kinder oder einen bellenden Hund getriggert wird. Dies ist bei der Lösung in diesem Thread nicht anders!

Die…

thgoebel

6. Januar 2022 um 13:25

You should be aware of a small disadvantage: If a door signal was received and signalised via the Shelly, some extra signalisation could occur if intercom is used to speak with the visitor. But this should not be very relevant…

George Kolitsas

Thank you very much for your reply! I managed to get this working with an esp8266 and a relay. I am able to get a volt reading from the A0 port of the esp8266 which is triggered when the doorbel is pressed.