Hello to all again,
I have attached my schematic of a project in development. i am using 2 X 5V power banks with a booster on each to bring up the voltage to 9 volts for my arduino and 12 volts for my buzzer and LED assemblies. I will be using transistors controlled by the arduino to switch on the LED assemblies and the buzzer. I do not know how to connect the grounds .
should the transistor emmiter go to the 12 volt ground from the booster or the ground from the pin from the arduino?
also , should I connect power bank grounds together? I’m at a loss at understanding this side of my project.
any help will be greatly appreciated, dermot