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 ...

This little sub‐schematic is simply the “brains” of a tiny I²C-driven relay board, built around an ATtiny84 programmed with an Arduino-style bootloader. Here’s what it does, how it’s powered, what ...