Recommended · for some experience
Low Power Arduino! Kill Power Circuit Tutorial
Why people recommend it
Shows an Arduino cutting its own power through a transistor after a button press, offered as an example for battery projects that need near-zero standby current.
In their words
If you aren't powering this with a battery, use something like this (SE) (the first answer) or this (youtube) (recommended) instead, then a pushbutton is enough to tell the arduino to power down, and the arduino itself cuts off the power, after resetting all of the neopixels.
ambitiose_sed_ineptum on electronics.stackexchange.com, Nov 2016. CC BY-SA.
Then when the Arduino sees that the button is pressed, save the data and turn off the power to the Arduino using a transistor (one example).
Gerben on arduino.stackexchange.com, May 2018. CC BY-SA.
