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ESP8266/Arduino 24v DC common ground?

Discussion in 'Microcontrollers, Programming and IoT' started by ApexDestroyer, Feb 28, 2018.

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  1. ApexDestroyer

    ApexDestroyer

    24
    4
    Feb 13, 2018
    Attached is a picture of the relay module and a crude sketch of my design.

    20180227_073816 (1).jpg
    The 24v power source powers the 24v relay module and a receiver PCB. The RX PCB receives an external signal and sends a momentary 24v trigger to relay 3 which is connected to a pin on the Arduino. Relay 3 momentarily opens and activates a home automation response.
    91l5C1Sz86L._SL1500_.jpg
    Relays 1 & 2 are connected to my garage door openers and to the Arduino. The Arduino triggers them.

    I'm new to this so these might be dumb questions.

    Should I use a common ground by connecting the ground pin on Arduino with the 24v ground supply?

    Will the 3v (haven't tested the current yet) from the Arduino be enough to trigger the relays 1 & 2?

    Am I missing something else?
     
  2. Bluejets

    Bluejets

    3,629
    732
    Oct 5, 2014
    Diagram has several (many)errors.
    What is the transmission signal on the Arduino supposed to represent?
    Do you have specs on the relay unit and which Arduino are you using and what voltage ( why 3v).

    Common grounds are usually the norm but there are exceptions.

    What are the garage +- squares supposed to be?
    If they are relay coils, they're never going to work like that.
    What voltage is you Rx unit? Any specs?
    Why is it necessary to use 24v system?
     
  3. ApexDestroyer

    ApexDestroyer

    24
    4
    Feb 13, 2018
    Thank you for taking a look at it. This is a project that my son and I are doing together.

    1. The transmission signal represents the wifi connection.
    2. Link to relay module
    3. It's actually the LoLin NodeMCU board with the ESP8266 wifi module.
    4. 3.3v from GPIO pins to relay and back to ground.
    5. The garage +- is just the garage door opener terminals to trigger the open/close. no relays.
    6. The Rx board is natively supplied 24v DC and outputs a momentary "trigger" with the same voltage as the input. (It will run on 12v but I don't want that to degrade the antenna strength)
     
  4. ApexDestroyer

    ApexDestroyer

    24
    4
    Feb 13, 2018
    It may also be useful to know that the NodeMCU board to the relay module and 24v supply are 50' from each other.
     
  5. Bluejets

    Bluejets

    3,629
    732
    Oct 5, 2014
    The relay unit inputs require a low signal to turn each relay coil on.

    A 24v trigger from your Rx unit will not work unless it is a negative going signal and even then, may be too high a voltage for the relay unit.
    Normally these input pins are connected to uC pins with between 3.3v and 5v.
    There was no spec sheet at the link you provided and I found a similar unit but very little detail.

    Possible you can provide a spec sheet link for your relay unit?

    So you have two incoming radio signals?
    Where are you getting power for the mcu?

    Cannot follow what you are trying to do with pin 3.
    Common ground to the mcu is required as you are using mcu pins to give a control signal to your relay unit.
    Why do you have it also going to a relay c/o contact also which connects to ground?
    Appears to me that at some stage this will be a dead short.

    So the 2 garage operators require voltage free switching?
    Your markings of + and - are confusing.
     
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