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 design uses I2C control to adjust a regulator’s output voltage plus or minus 127 steps in 5 mV increments. Using an I2C-controlled DAC (IC2) to inject current into the feedback node of a stepdown ...