Hi I could not solve my problem. I have the house intercom that has a voltage of 12v. I would like to be notified by blynk when they ring me. What can I do?
Ciao non sono riuscito a risolvere il mio problema. Ho il citofono di casa che ha una tensione di 12v. Vorrei che quando mi suonano mi arrivi una notifica tramite blynk. Cosa posso fare?
Google, Research, Read, Study, Experiment, Have fun learning… 
90%+ of your issue will be hardware & interface related… Absolutely nothing to do with Blynk until that last little bit… then it might be something like this basic button poll example.
A lot of intercoms seem to work on AC, so take care with that.
You’ll probably find that if you take the cover off of the intercom in your house/flat then there will be a speaker that is used to create the ringing tone when someone presses the external buzzer.
This may be the easiest way to interface with the intercom, maybe via a diode to ensure that you’re not getting any nasty negative spikes. Measure the voltage that you’re getting between one of the speaker terminals and ground and if it’s between 2 and 3.5 volts you could probably use this to trigger a digital pin on an ESP8266. The ESP and the intercom would need to share a common ground, but you won’t want to power the ESP with anything higher than 5v.
Pete.
that wouldn’t be a trivial task without a scope…
with a standard dmm, there is no chance you can detect those ac spikes which are feed into the speaker. otherwise the idea is good.
Does your intercom have a LED which changes state as the intercom is used? You could use a light detecting diode to detect if the LED is active.
Hello and thanks for the reply. I measured the voltage on the speaker and I have 12v. What I do not understand and how to interface the 12v with arduino. If I can abort the
Tension at 3 or 5 how do I put the negative in common? Can you make me a scheme? The code just use the code for the notification?
Ciao e grazie per la risposta. Si ho misurato la tensione sull altoparlante e ho i 12v. Quello che non capisco e come interfacciaare i 12v con arduino. Se riesco ad abassare la
Tensione a 3 o 5 come metto il negativo in comune? Potete farmi uno schema? Il codice basta usare il codice per la notifica?
No I only have the output voltage at 12v when they sound
No ho solo la tensione di uscita a 12v quando suonano
You could use a simple voltage divider using a couple of resistors. That won’t give you any real over voltage protection, but you may feel that none is needed.
Alternatively, you could use a small 12v to 3.3v buck converter.
Nobody is going to be able to give you a readymade solution, because that solution will depend on the entry phone and the MCU hardware that you choose to use. You’ll need to do some experimentation to get the right results. If you’re not able to do that then maybe this project isn’t for you - yet.
Pete.
Doorbells are usually AC voltage… I would recommend some form of galvanic isolation between the doorbell circuitry and your MCU (optocoupler, ACS712 current sensor, magnetic read switch, etc.) As stated this is all well beyond this forums purpose, but a quick search on Google pops up many options.
hi my friend,
I thought about connecting a 12v bulb so when I play it it turns on.
then facing put a photoresistor and with the high value when the bulb is on send the notification. I did the whole circuit but I miss the code. could you help me? thank you
hello Lucio
you could connect a 12 v relay on your PCB intercom, between ring wire and GND, so when someone rings, relay closes contacts, that contacts should be connected to a digital pin on the mcu , just a few code like blynk.write(Vx) …
that 's ok for you ?
Hi. I tried to connect it to the 12v relay. but how and what I connect to the arduino. for example, pin 2 to what
Just a reminder… This is a Blynk forum, for learning about Blynk and how to use Blynk, not a generic “show me how to wire up and code somthing” forum 
I suggest you use G 
gle and some of the thousands of sites and tutorials on how to wire up doorbells, etc to Arduinos… then once you have that working we can help you integrate it into Blynk.
No against helping with wiring and such… have done so many times…
Problem I am seeing here is that this OP has asked simular non-Blynk related questions, including doorbell ones, and usually didn’t follow through with requests. And this time, aside from this one vague question…
… this OP again hasn’t mentioned, questioned or shown progress on anything Blynk related yet.
I’m not trying to shut this topic down… but I would like to see something, bennifitialy Blynk related, shared back and forth from the OP to make it worthwhile for others to read and reference.
