Not exactly schematics, but [Duckman] has some Arduino pinout diagrams he made using ASCII-art. These could be useful when pasted into source code as comments, documenting the pinouts for your ...

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.

“The Arduino Nano is a small, complete, and breadboard-friendly board based on the ATmega328 (Arduino Nano 3.x). It has more or less the same functionality of the Arduino Duemilanove, but in a ...

In this circuit, a MOSFET protects a reverse-connected battery from excessive current. The MOSFET conducts only when the battery is correctly connected, which lets the battery charge or discharge. In ...