Constant 12V to momentary

[DPluss]

Hey!

I'm building a bluetooth proximity garage door opener.
I've got a bluetooth relay modul which has a NO and NC state, once the bluetooth connects the relay closes, however it provides constant 12V after connecting, and I only need a momentary signal(like a button press on my remote) for my garage opener. What is the simplest and most efficiant way to convert this constant 12V to just a momentary?

My idea is, bt searches for phone constantly -> finds it, triggers relay NC -> constant to momentary -> garage opens -> if it gets turned off relay NO state -> triggers another constant to momentary -> garage closes

Thanks in advance!

 

[betwixt]

We need more information about the Bluetooth module to answer this. I have never heard of a proximity detector that simply operates in the presence of any signal so I assume it has some intelligence, at least enough to pair with the transmitter. From there it may be possible to reconfigure or reprogram it with no further intervention. Otherwise, the only solution is electronic - to add a monostable between the detector output and the relay driver.

Brian.

 

[KlausST]

Hi,

I agree. It´s unclear to me, too.

once the bluetooth connects the relay closes, however it provides constant 12V after connecting, and I only need a momentary signal(like a button press on my remote) for my garage opener.

From the discription I thougt that there is a relay .. with contacts to connect to the garage opener.
But then you say "it provides 12V". What provides this 12V? Is the 12V at the coil of the relay? Or do you connect the 12V to the relay contact?

And what do you mean with "most efficient"? In regards of power consumption?

Klaus

 

[DPluss]

We need more information about the Bluetooth module to answer this. I have never heard of a proximity detector that simply operates in the presence of any signal so I assume it has some intelligence, at least enough to pair with the transmitter. From there it may be possible to reconfigure or reprogram it with no further intervention. Otherwise, the only solution is electronic - to add a monostable between the detector output and the relay driver.

Brian.

Hi,

I agree. It´s unclear to me, too.


From the discription I thougt that there is a relay .. with contacts to connect to the garage opener.
But then you say "it provides 12V". What provides this 12V? Is the 12V at the coil of the relay? Or do you connect the 12V to the relay contact?

And what do you mean with "most efficient"? In regards of power consumption?

Klaus

It is called 'Bluetooth 4.0 12V Proximity Switch Sensor Module' I found it on ebay, it operates with 12V, and it has a single relay, there is a NC and NO state, and a common feed(which I use with 12V) once the phone connects to it closes the NO state on the relay, if it disconnects it goes back to the NC state. The problem with this, that its constant voltage output and I only need a momentary signal(like when you press a button on a remote), I've found a circuit labelled as "Constant to Momentary output' on the internet and testing it out today. By most efficient I meant that the piggyback circuit of the actual module needs an additional relay, capacitor, resistor per NO and NC state(the constant to momentary output thing) so that it opens and closes when the phone connects or disconnects.

Thank you for your replies and sorry for my 'blurry' details I'm still learning these things since its only a hobby thing

 

[betwixt]

With a quick search I can't find any specification for such a device, only that it detects Bluetooth. If it really does work on proximity alone, before going further do you understand that ANY Bluetooth device will open the garage door so someone walking by with a mobile phone for example could operate the relay. My car has Bluetooth, even driving by could open your door.

If that is what it really does, there are some serious security issues to consider. A device that has to be 'paired' to a specific Bluetooth source is FAR more secure and only gives control to authorized devices.

Try out your internet discovery but I suspect what you will need to do is either add a monostable circuit and another relay driver to the existing unit or start over with a simple completely new device. They are quite easy to make and very inexpensive. I have a Bluetooth system here that lets me switch the lights on and off around the house, it cost almost nothing and is paired to my phone and tablet devices, it uses an ESP32 module and a simple transistor to drive a relay.


Brian.

 

[DPluss]

With a quick search I can't find any specification for such a device, only that it detects Bluetooth. If it really does work on proximity alone, before going further do you understand that ANY Bluetooth device will open the garage door so someone walking by with a mobile phone for example could operate the relay. My car has Bluetooth, even driving by could open your door.

If that is what it really does, there are some serious security issues to consider. A device that has to be 'paired' to a specific Bluetooth source is FAR more secure and only gives control to authorized devices.

Try out your internet discovery but I suspect what you will need to do is either add a monostable circuit and another relay driver to the existing unit or start over with a simple completely new device. They are quite easy to make and very inexpensive. I have a Bluetooth system here that lets me switch the lights on and off around the house, it cost almost nothing and is paired to my phone and tablet devices, it uses an ESP32 module and a simple transistor to drive a relay.


Brian.

I dug into this module, it needs to be paired apparently, there are detailed instructions, only in chinese, I had to picture translate the chinese text from a video of a chinese youtube-like site, it was burried as hell. This BT module can also receive AT commands as shown on the videos, shame I dont really know how that works. Will look into your ESP32 module, actually if its not a big deal would you kindly write the details of that circuit?

Also thank you for your help Brian!

 

[betwixt]

This is a 'cut down' version of my program as an example. I have not tried to compile it or test it but the full version works perfectly. Use it as an example in the Arduino IDE (download from Arduino.cc):

// For WROOM32 module (like 'doitesp32' module)
// Pin numbers below correspond with markings on module.
// 'BLUE_LED' flashes when Bluetooth command is being executed.
// Tested with 'BlueSPP' Android app although any terminal program should work.

#define RelayTime 1000

#include "BluetoothSerial.h"

BluetoothSerial SerialBT;

int BLUE_LED = 13;    // flashes 4 times on start-up and once when Bluetooth command received
int RelayDRIVE = 27;    // Main lights. Wired so K1 energised when AC is ON (to save battery life)


void setup()
{
  pinMode(BLUE_LED,OUTPUT);  
  pinMode(RelayDRIVE,OUTPUT);
  
  digitalWrite(BLUE_LED,LOW);
  digitalWrite(RelayDRIVE,LOW);

  SerialBT.begin("Door opener"); //Bluetooth device name
  for(int flashes = 0; flashes < 4; flashes++)
  {
    digitalWrite(BLUE_LED,HIGH);
    delay(250);
    digitalWrite(BLUE_LED,LOW);
    delay(250);
    
  }
}

void loop()
{
  // see if Bluetooth has connected and received a command
  
  if (SerialBT.available())
  {
    digitalWrite(BLUE_LED,ON);
    
    int Command = SerialBT.read();
    
    while(SerialBT.available()) SerialBT.read();
    
    switch(Command)
    {
      case '0': digitalWrite(RelayDRIVE,LOW);
                break;
      case '1': digitalWrite(RelayDRIVE,HIGH);
                break;
      default : digitalWrite(RelayDRIVE,HIGH);
                delay(RelayTime);
                digitalWrite(RelayDRIVE,LOW);
    }
  }
  
  digitalWrite(BLUE_LED,OFF);
  delay(20);
}

You can see it isn't complicated!
It does need pairing but doesn't use a security code, that means it will not activate simply in the presence of a signal, some manual intervention is needed. When connecting it should identify itself as "Door opener" and it should respond to a simple text command:
'0' turns the relay off
'1' turns the relay on
anything else turns it on for a period then turns it off again. The duration of the period is set in the line "#define RelayTime XXXX" where XXXX is in milliseconds (1000 milliseconds = 1 second). It should work with any Bluetooth source, I use a mobile phone or a tablet.

You need a transistor to drive a relay or to directly drive the door motor, connected to pin 27 of the module. See if you think this is within your capability before I draw a schematic. To find the module I used, search: "ESP-32 ESP32S Development Board 2.4GHz WiFi+Bluetooth Antenna CP2102 Module".

Brian.