The hardware is fairly simple, everything is based on already built modules, and I did not have to use any PCB or proto board.
It is composed of:
- A power supply for LEDS, I took a standard LED 12 V 5 A with a case similar to laptop PC.
- An Arduino Nano, wich integrates directly the USB Serial Interface and has a very suitable form factor for this project where there is no need to use shield.
- A MOSFET power switch module to drive the LED in PWM mode.
- A Relay to drive room light. As the Arduino and the Relay are powered through USB (did not want to setup a dedicated power supply just for that), I chose a solution that draws as less current as possible. And the solution is to use a bi-stable relay with two coils that are powered very briefly to toggle the contacts (50 ms). So, with the help of a capacitor, power budget drawn from USB is negligible.