Sean Michael Ragan at Make wanted an easy way to turn off his own projects without having to disconnect the whole battery. He couldn’t find a 9V power switch to buy, so he made one himself. To ...

Posted in Arduino Hacks, Microcontrollers Tagged adc, arduino, atmega, attiny, battery, low battery, power monitor, voltage ← Homebrew Gel Fuel Keeps The Steam Coming, Legally ...

You can also go the 9v battery route plugged into the on-board regulator of the Arduino but the low mAh rating of a 9v won’t allow your project to stay running for very long.