I am trying to build my own IOT smart home and as a first step, I used the following components to build a module to control ligts and fans:

To power up the module, I am designing a power source and I am stuck at this step: I am unable to calculate the total power supply required for the whole module(above listed parts) to work. I am planning to use a single source of power supply, and from there power up all the components. This power supply would take 220V as input and should give out 5V/3.3 V as output. What should be the Ampere that the power supply should be able to provide?

I am new to electronics, Please help me understand the power requirements for the components especially how much Amps is required totally by each component and also how to build a power supply that would be able to power up all the components with safety controls. What safety features should I follow? Thanks for your help.

Edit: I am willing to learn as I have come this far by learning looking at blogs and videos. But for this power supply I am not able to find any resource to build. Thats why I have turned to stack exchange for help.

  • First thing first: build your project first; power supply can wait. – user31481 Feb 18 '18 at 8:41
  • I have built the project. Right now I am powering everything using USB cables. How do I get rid of USB power supplies and power the project using own standalone power supply? – krish Feb 18 '18 at 8:42
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    Start by reading the datasheets. – Ignacio Vazquez-Abrams Feb 18 '18 at 8:48
  • So you now can measure the real power needed. Just use a multimeter to read the input current. – user31481 Feb 18 '18 at 8:53
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    I'm voting to close this question as off-topic because it is overwhelmingly not about Arduino but rather about determining the power consumption of undocumented peripherals. Hint: start with the 8 relay coils, get published figures for the Arduino and Node MCU, put in a healthy safety factor. – Chris Stratton Feb 18 '18 at 17:04

The reason you do not find "Good" answers for the power requirements for micro controllers is that there are too many variables. Your Best bet is to get a multimeter that can measure current, and use it to test your project in its full running mode(relays, wifi, led's, everthing that will be running) If you have distinct states that draw different power make sure you take note of what which one draws the most amount of current and then add in a safety margin(using 25-50%)

Then you need to decide the form factor of your supply. You can get very small AC-DC converters if you want to build this into a light switch or other wall outlet. look at these (3.3v)

this has 3.3 and 5v

However, I would start by prototyping your modules, and just using existing plugs (like for phones) that already do 120v to 5v (usb) while you trouble shoot the code and logic of your project. And then once everything else is working you can work on final form and power supply

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