Noob seeks advice on small scale home automation project

I am a total noob when it comes to the Arduino and would appreciate any help that anyone here may be able to provide as I am very keen to learn more about home automation.

To begin I want to create a sort of home automation dollhouse so that I get the idea on a small scale how it might be for when I eventually could implement it in a house down the line and this also will be showcased in my College as part of our Raspberry Pi and Arduino Society's projects.

At the moment I have a basic two storey wooden dollhouse, a Raspberry Pi and an Arduino Mega that I'd like to have control some LEDs, switches, sensors, Fans and some other components which we have lying around our project room.

My first query is around having enough a large enough amount of power to be supplied to all these components as from the plans we have so far there will be :

  • 6x RGB LEDs
  • 2x Normal LEDs
  • 2x humidity and temp sensors
  • 1x sound sensor
  • 1x motion sensor
  • 1x RFID scanner
  • 2x fans
  • 1x piezo speaker

From reading online I have seen mentions of external power supplies being used and power shields but in honesty I couldn't understand what might be best for me so any help on where to begin would be awesome.

Thanks for reading and I hope I have included enough information for some one to help or point me in the right direction.

I think the only things that would need a separate power supply are the fans. The Arduino I/O pins are capable of providing about 20mA (the 40mA absolute max should be avoided) so they can power LEDs with suitable current limiting resistors.

Without knowing what specific sensors you propose to use it is impossible to say if they need more than 20mA.

As general guidance break your learning into small parts. Write a short Arduino program to work with each item on its own. Only start bringing them together after you know how to do everything separately

You may find some ideas in Planning and Implementing a Program although it was not written for a complete beginner.


I agree with Robin that the only significant power pulling parts are probably the fans. You may not need an entire shield. You may be able to create the circuits yourself as they are really not that difficult. The Basic principle is that the Arduino digital pin sends a very low power Signal to a separate Switch (consisting of a Transistor or MOSFET). The Switch is connected between the external power supply and the load (i.e. fan). You will find plenty of samples in this Forum (try the power Forum) or elsewhere in the Internet.

There are several examples for Aduino circuits on the Pigihxx website


Thank you very much Robin2 and JaBa for both of your advice.

I have started by getting the individual components and sensors to work one at a time and the Arduino and feel more confident now about trying to add more to build it up now as previously was worried about potentially damaging the Arduino when hooking up too many of even the LEDs at once.

I’ve managed to find some other great help from older posts in this forum too so am very glad this forum exists.

Thanks again.