[Need help] Intercom project

[Sparkman]

@PandaNL It's unlikely that a single wire is used for the relay. Typically these systems work by superimposing different signals on the same two wires. The voice will be on that pair and so will the control signal to open the door. The control signal for the relay could be a dc voltage of a certain level or an ac signal at a specific frequency. There's equipment at the head end that will take this signal and operate the relay. It's unlikely that you are directly controlling the relay that opens the door. Hook up a multimeter across the pair and measure ac voltage and then dc voltage while you are making a voice call and opening the door. Start at 50v or so and work your way down to lower levels if you don't pick anything up.

Cheers
Al

[PandaNL]

Hi Sparkman,

Used the multimeter and it gives a reading of 20v dc. when the button for the door is pushed two metal parts touch each other and will send a signal to open the door.

Soldered 2 wires to those connections and it seems to work with the relay, the only thing I need to figure out now is how to get a signal when someone rings.

[Sparkman]

@PandaNL said:

Used the multimeter and it gives a reading of 20v dc. when the button for the door is pushed two metal parts touch each other and will send a signal to open the door.

Soldered 2 wires to those connections and it seems to work with the relay, the only thing I need to figure out now is how to get a signal when someone rings.

Good news. For the ring, it's likely a 60-90v ac signal, so use the multimeter to confirm that. There are pre-built ring detectors available, one example is made by Velleman, or you can build your own. Google "telephone ring detector circuit" and you should be able to find examples.

Cheers
Al

[PandaNL]

Could I also use a ACS712 30A Module to see if there is a change in voltage with a script in domoticz?

[Sparkman]

@PandaNL It might work. Won't hurt to try it.

Cheers
Al

[PandaNL]

The ACS712 should arive today, however I couldn't find the sketch to send over the voltage measurements, maybe I'm overlooking but which sketch can I use?

[Sparkman]

@PandaNL I would hook the module to a volt meter first to see if it picks up the ringing signal. Once you have that working, any sketch that measures an analog signal can be readily modified for this purpose.

Cheers
Al

[PandaNL]

Can't seem to get a good readout from the module yet.

Tried the following code

/*
Measuring Current Using ACS712
*/
const int analogIn = A0;
int mVperAmp = 185; // use 100 for 20A Module and 66 for 30A Module
int RawValue= 0;
int ACSoffset = 2500; 
double Voltage = 0;
double Amps = 0;

void setup(){ 
 Serial.begin(9600);
}

void loop(){
 
 RawValue = analogRead(analogIn);
 Voltage = (RawValue / 1023.0) * 5000; // Gets you mV
 Amps = ((Voltage - ACSoffset) / mVperAmp);
 
 
 Serial.print("Raw Value = " ); // shows pre-scaled value 
 Serial.print(RawValue); 
 Serial.print("\t mV = "); // shows the voltage measured 
 Serial.print(Voltage,3); // the '3' after voltage allows you to display 3 digits after decimal point
 Serial.print("\t Amps = "); // shows the voltage measured 
 Serial.println(Amps,3); // the '3' after voltage allows you to display 3 digits after decimal point
 delay(2500); 
 
}```

It gives me the following readout, tried the multi meter on signal and also a lamp on ac. It shows these values even if nothing is connected. Connected the module to pin 0 on the arduino and provided it with 5v from the arduino.

Raw Value = 876 mV = 4281.525 Amps = 9.630
Raw Value = 877 mV = 4286.413 Amps = 9.656
Raw Value = 878 mV = 4291.300 Amps = 9.683
Raw Value = 877 mV = 4286.413 Amps = 9.656
Raw Value = 877 mV = 4286.413 Amps = 9.656
Raw Value = 875 mV = 4276.637 Amps = 9.603

What would be the formula to just show Voltage?, when the door is ringed the voltage changes from 20v to 23~24v, when the button is pressed to open the door it drops to 17v.

[Sparkman]

@PandaNL How do you have your module hooked up to the wiring?

Cheers
Al

[PandaNL]

By splitting one line, so for the intercom the black cable to the module, then a cable from the module to the connector where the black cable was connected.

Same for the lamp.

[Orri]

This is the only place where I could find a picture of this exact model and I wanted to know what the left buttob does. It looks like a light or something but it doesn’t do anything. Also, how did you open it up? I couldn’t find any screws

[bjacobse]

@orri

Did you read the manual? if not read below...
In-house telephone light button Each in-house telephone has a light button to actuate a joint staircase or entrance light.

https://www.siedle.com/App/WebObjects/XSeMIPS.woa/cms/documentdownload/locale.enGB/did.7750/System_Manual_1%2Bn_technology_136442_EN.pdf