Ideas for a Smart Switch for IoT project

Discussion in 'Embedded Systems and Microcontrollers' started by ideepuraj, May 24, 2016.

  1. ideepuraj

    Thread Starter New Member

    May 24, 2016

    I am planing to do an IoT project for home automation and i need some help to design a smart switch circuit to control the home appliances with out changing the existing infrastructure. Below is the block diagram of a sample switch which can be controlled using a GPIO pin and need some capabilities to measure the current. Also the circuits needs some isolation for the AC main .


    The basic requirement is to control the AC load using both the existing AC switch and the Digital circuit block "X" with some option to measure the current used. Please provide your suggestion on how to start with the same.

  2. NorthGuy

    Active Member

    Jun 28, 2014
    If the "AC switch" is closed, at least some of the current will flow through the "AC switch", so it will be impossible to measure current at point "X". If you want to measure current you need to install some sort of sensor (e.g, current transformer) on wire P (or N).

    As drawn, if the "AC switch" is on, there's no way to turn the load of with the "X" device. Similarly, if the "X" device has closed the contacts, it's impossible to turn the load off with "AC switch". Is that what you want?
    ideepuraj likes this.
  3. shteii01

    AAC Fanatic!

    Feb 19, 2010
    ideepuraj likes this.
  4. ideepuraj

    Thread Starter New Member

    May 24, 2016
    Thanks for you suggestions. I understand the risk of switching of the device if any one of the switch is closed. But do u have some circuit option which u can suggest for this purpose ?
  5. be80be

    Distinguished Member

    Jul 5, 2008
    Three way switch and single pole double throw relay