Enter the ExtraCore library for Arduino, a software library that turns two or more Arduinos into a multi-core microcontroller with more pins than you’ll ever need.

When the button is pressed the Arduino board will put pin 2 in HIGH state, meaning 5V on pin 2. This voltage is used to drive the transistor that will switch ON the relay and the load (in our case the ...

PWM pins work the same way across all Arduino boards, so you don't need to go out of your way to buy a Mega if you already have a board supporting PWM. On the Uno, Nano, and Mini, the PWM pins are ...