Advice needed. Maybe a stupid question
but I would like to illuminate my PC case with a RGB strip and sync it with the PC HDD activity LED. I would like to power the Arduino board, RGB strip and the RGB module with 12v from the PC power supply and use analogue read with the positive output of the HDD activity LED pin on the motherboard.
As far as I know the 3.3v, 5, and 12v on the power supply all share the same earth.
Would I be right in saying that the ground from the HDD activity LED output doesn't need connecting because the Arduino board is powered by the same earth?