back up source for arduino UNO

I'm making arduino UNO school project, then i have a problem of how to build an automatic backup source for arduino uno... Please help me

-sorry for my english!

What do you mean.

I think China is the largest backup source for Unos. Leo..

Power source? Like a battery?

USB "power bank" batteries are pretty common now. That may do what you want. When the voltage on the Arduino's Vin is high enough (6.6V or so) then it won't draw any power from USB.

what I mean is a backup power supply when the main power source is off, like for example blackouts, power shortage etc.

UPS

If you have a rechargeable battery such as a car battery or one from a toy then connect it to both the Uno and the charger.

Be aware that you cannot take a lot of power from the Uno's 5V when it is powered from 12V. Then a separate voltage regulator is required.

can you help me how to do it? like schematic diagrams.. please boss!..

-I'm Newbie in using arduino Uno!

Here you go...
BackupPower.png

BackupPower.png