I have a project where I have made an arduino on a breadboad and i am using it to control a motion sensor and some small 12V lights. I use a wall wart that outputs 12VDC 1500mA. On the breadboard i use a LM7812 to regulate 12V to one rail on the breadboard and then I use a LM7805 to regulate 5V to the breadboard's other rail.
Is it possible for me to hook pin 8, 9, and 10, to the ground of the 12V rail...?
4. On the schematic it says use a TIP102 transistor for larger relays. Does this mean with any relay over 5V? I have a TIP 120 transistor would this work…?
5. Do I just need to make sure all grounds are connected even when there are different Voltages?