You can use a 6V to 20V unregulated external power supply, but the recommended range for the Nano is between seven and 12 volts only. To be safe and prevent any damage to your board or components ...

Both the Arduino Nano and Uno can be powered via their integrated USB connectors. This automatically supplies regulated 5V power to the board, allowing you to use any USB-supported power source ...

“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 ...