B4R Question d1 mini 8266 help - question

[user_an]

Hi all,
I need help with a connection for my d1 mini. Please forgive my ignorance as I am very new to this.

So, the doorbell in the house is video doorbell. It has 2 wires that expose 27.3 volt in idle mode (black screen etc) and when someone ring the bell ti goes to 26.5 - 26.7.
Ideally I need to know when someone is ringing the bell. So I thought to use a transformer to step down to 3.3 volts or something less and attach it to d1 mini.
I saw some videos and I suppose to connect the ground of transformer to the ground of d1 mini, and the other wire to A0 of d1 mini.

My first question is, if it is ok to proceed as above.
I am not sure if 1 of my 2 wires of my video door bell can be considered as a ground?

My next question is if with the above set up is a way to power the also the d1 mini. This is ideally. I don't have a plug near to connect it with 5v phone charger which is my favorite choice.

** One key problem I saw is that if I connect these 2 wires the camera reboots so I am not sure at all that how and if this can work or what else alternatives I have

Again, I know that I'm asking very basic and probably stupid questions, but I'd appreciate if you could help.

Thanks

 

[derez]

1. Is it DC or AC ? a transformer works on AC, if it is DC you need something like this "LM2596 DC-DC Buck Converter Adjustable Step Down Voltage Regulator 3-40V to 1.5-35V High Efficiency Power Supply Volt Reducer"
2. The difference between 27.3 and 26.7 , after downconverting, is null so you will not be able to tell when the ring button is pressed...
3. Check again the voltage on the wire that comes out from the ring button, it does not make sense. I guess it is 0v when not pressed and above 0 when pressed, or vice versa.

 

[user_an]

1. Is it DC or AC ? a transformer works on AC, if it is DC you need something like this "LM2596 DC-DC Buck Converter Adjustable Step Down Voltage Regulator 3-40V to 1.5-35V High Efficiency Power Supply Volt Reducer"
2. The difference between 27.3 and 26.7 , after downconverting, is null so you will not be able to tell when the ring button is pressed...

Yes, it is DC. So you are saying that the difference is so small that this method won't work. I was afraid for it.
Do you know what is the minimum difference required?
Suppose the it could work do you know what I should do from the same setup to power the d1 mini?

 

[derez]

As I wrote above, you need a down converter but it will convert whatever voltage above to the selected low voltage, so it is ok for powering the D1 but not for signal detection.
For the signal - do as in 3.

 

[KiloBravo]

In the US traditional door bells are AC. Mains (120V) goes to an AC transformer that drops it to about 26 volts.
One wire of the AC Transformer goes to the solenoid on the door chime. The other wire goes to the door bell and then back to the other side of the solenoid. When you push the door bell you are completing the circuit from the AC transformer to the solenoid.

Google "Door Bell Circuit" and look under Images you will see what I mean.

I believe the small voltage drop you are seeing is just the solenoid turning on to strike the chime plate.

But if you have a video door bell someone may have changed the wiring from the transformer and rectified the AC to DC.
Google "ac to dc circuit".

But IMHO you are see 27 volts AC. (I have been wrong before.)

What does the Door Bell Camera input voltage require ? Is it powered by those two wire or something else ?

The two wires connecting (pressing the door bell) may switch a relay on in the video camera to turn it on.
Which is why if you connect them and leave them connected the camera reboots.

 

[josejad]

Hi:

I have no idea (you know, the basics) about electricity or AC/DC current, but with the help of the forum and some friends, I got this working, and maybe helpful. Our doorbell works at 220v, and with a 220 relay, we just get an 0 or 1 when the doorbell is pushed.

Garage Door Opener (with source code)

Hi all: *** ADDED Project with B4XPages working on B4A and B4J. See post #15 Not sure if this is the rigth place, or if I should publish it in Examples, @Erel, feel free to move. The code is not perfect, but it works. Most of code is copied/pasted/modified from forums, so this app is made by...

www.b4x.com

 

[KiloBravo]

That was kinda where I was going. Add a relay in the circuit and look for a one or zero and power the mini with a battery. It would sleep most of the time. The battery should last a long time.

Mains AC (120v or 220v) is nothing to mess around with if you do not understand the basics!

 

[user_an]

Thanks everyone. I was on a business trip so I couldn't answer. As I said I am new to this world and I have to read and watch video guides on how to proceed.
I like the above idea with the relay but again right now I don't understand exactly what I have to do.