Hi, since I blew up in the past an Arduino trying power circuits, now I prefer to be really sure of what I'm doing. Thank you for the support and for trying to understand my bad english.
I need something that give to my arduino to shut down itself. Let me explain: I power it up, it checks the voltage, it finds it's too low, it shuts down itself.
I was thinging to put an NPN in series with GND, a power on pushbutton and a digital pin both attached to the base of the transistor. To power the whole thing I would press the pushbutton and a start up routine will start, and mybe after 3 sec puts the digital pin to HIGH. At that time I would be able to release the pushbutton. In the startup routine and every 30 sec Arduino checks the voltage and if it is low, put the digital pin to LOW and everything should switch off.
In your opinion can this work? Did I miss something like a diode or other hardware?
Thank you again, Luca