In this quick Arduino tutorial I will explain how you can control a relay using the Arduino Board, one 1K and one 10K resistors, 1 BC547 transistor, one 6V or 12V relay, one 1N4007 diode and a 12V fan ...

Here is the circuit of an Arduino ... of prototyping board. You can use any standard 9V battery to power the whole circuit, and the Push-ON (push ‘n’ hold) switch (S1) to activate the alarm function.

If you’re just doing something simple like switching a relay or powering a LED, you might want to think about the Digispark. It’s a very small ATtiny-based Arduino compatible board developed ...

The Uno Rev3, is a great beginner board as it's included in many starter ... bigger LEDs or even a light bulb (paired with a relay for the Arduino Uno). Try a toggle switch instead, so you won ...