I am attempting to power up battery powered (4.5V) LED strips and an arduino with the press of one button.
I read that you can have multiple voltage sources sharing a common ground, and I am trying to use that to switch everything on and off.
This circuit was working when before I swapped out a weaker 9V battery (was down to about 5V) with a fresh one. After swapping, the arduino is now powering on, without the switch being engaged.
What am I doing wrong?