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Can someone explain to me how this circuit works?

Discussion in 'General Electronics Discussion' started by irq20xdfr, Apr 12, 2018.

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  1. irq20xdfr


    Aug 12, 2016
    Hello everybody,

    I have in my house an automatic front door for my car, this has a remote control. I'm trying to use an arduino mega and ethernet shield to create a service to open my door using an Apple Watch App.

    I am a programmer, i don't have too much experience with cuircuits and electronics, i barely know how some components work.

    What i'm trying to do is to replicate the function of the button in my garage to open the door, i dont want to use the rfid part, i have this circuit, that, for what i understand it is just a simple cuircuit that gets closed when the switch is pressed.

    What i don't understand is what the capacitor and resistor is for? and how everything (the paths and the components) work?

    If someone can help me to understand this and to guide me so i can replicate this in a protoboard, so i can just send a digital signal to a port in my arduino and activate the circuit, i will be so thankful.

    currently i have the arduino program working, event the app, what i dont get is how to activate the cuircuit, i have heard that i need a relay, i am currently investigating about that, but i want to know more about the circuit job.



  2. kellys_eye


    Jun 25, 2010
    The resistor is a simple 'dropper' to limit the current to the LED and wired across the two main terminals.
    The capacitor seems to be wired in series with SW1 and whole arrangement is across the two main connecting terminals.
    SW2 is straight across the two connecting terminals.

    Basically THREE circuits wired in parallel across the two screw terminals.

    Looks like the controlling circuit is using the 'delay' introduced by the capacitor to detect which of the two buttons is being pressed (SW1) whilst SW2, when pressed, is an immediate 'short'.
  3. irq20xdfr


    Aug 12, 2016
    Ok kellys_eye, thank you so much, now i understand how everything is related...

    But how could i replicate this in a protoboard? What do i need? resistor, capacitor (of the same uF), dupont cables?, a switch?(i just want one, the other one SW it is not used for my door), and a relay so i can close the circuit with a digital pulse?

    Thank you all in advance...
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