I want to buy an Arduino Nano 3 but it seems that it can be powered only by USB.
I want to use it in some places where I don't have a computer so I can't power the Arduino.
- Can I use the VIN pin to power it?
- What voltage should I use?
According to the board's manual, pin 30 is VIN, which is in range 7-12V, or the pin 27 can be used as 5V output (if powered by VIN), or 5V input from external power supply. I strongly recommend to read related documentation before working with any new hardware.
How Eugene Sh. told you, you can give the power supply to your Arduino Nano (Rev.3 and previous) applying +5V DC on the correspondent pin and GND. You can also give the Power Supply applying voltage up to +12 V DC or on the VIn pin and GND. This is one good solution for the beginners that cannot use the USB as source of Power.
But there is also the solution to use a wall USB Power Supply (the battery charger of your phone) connected to the USB of your Arduino Nano.
Be careful!
As long as you dont have a long distance to run, I would use a USB wall adapter rated for 5V. If it's not too far use a USB extension which is about 4 to 6 feet long. The VIN and GND are an option but I only would do this if I could guarantee 5 volts. They say 5 to 12 but I would not trust that, that is totally up to you.