You engaged in a lot of electronic projects at once?
Well there might have been a lot of instances when you are out of some components and are too lazy to go out and buy some OR in some emergency situation where you need to charge your mobile phone battery??? IF YOU HAVE AN ARDUINO UNO YOU DONT NEED TO WORRY!!!!!

I have been in such situations a lot of times.
So I came up with this project utilizing the minimum parts required to make a simple yet powerfull power bank that can charge Androids, Iphones and any other phone that can charge through a USB port.

SO LET'S BEGIN!!!!!!!

Step 1: PARTS REQUIRED

There are a very few parts requierd in this project they are:-

* ARDUINO (it can be any type as long as it can run on 7v-12v and has a 5v regulated power pin i used UNO)

link:- http://arduino.cc/en/Main/Buy

*A BATTERY (I used a 9.6v 4000mAh hobby battery but you can use any 9v battery but i cannot promise any charging performance)

link:- http://www.ebay.co.uk/itm/New-Practical-New-AA-9-...

*USB TYPE A FEMALE PLUG(You can also savage it from some old computer motherboard)

link:- http://www.ebay.co.uk/itm/2x-USB-2-0-A-Female-Plu...

*A 220Ώ RESISTOR(Read more about it here:- en.wikipedia.org/wiki/Resistor )
*A 470μF ELECTROLYTIC CAPACITOR (Read more about it here:- en.wikipedia.org/wiki/Capacitor ‎)
*SOLDERING IRON AND SOLDER (not necessary, you can also use a solderless breadboard)
*A HUMAN BRAIN AND HANDS

IN THIS PROJECT I ASSUME THAT YOU HAVE SOME SOLDERING EXPERIENCE.

Step 2: THE CURCUIT

The curcuit is very easy.
A 220Ώ resistor goes between the two data pins D+ and D-(don't worry about the polarity insert them any way you want between the two pins)
And a capacitor will go between the two power pin of the USB Plug(mind the polariity while soldering)
and solder some extention wire to the power pin that are 5+ and 5- pins
Connect the positve and negative power cables comming from the usb port to the 5v output and ground.

Refer to the below diagram for the connections and the USB pinout.

Step 3: CONNECING THE BATTERY

So we are almost there.

Attach your battery's positive and negative to the VIN and GROUND of your Arduino board.

PLEASE MIND THE POLARITY WHILE CONNESTING POWER SOURCES OR YOU WILL END UP FRYING YOUR ARDUINO BOARD.

Step 4: THE CODE FOR ARDUINO

Well I mentioned that this was a project for emergency and therefore does not require any Arduino code............
So for this project don't open the Arduino IDE and relax.

Step 5: TESTING AND WARNING

I RECOMMEND YOU TO CHECK THE OUTPUT OF THE USB PLUG WITH A MULTIMETER BEFORE CONNECTING YOUR PHONE TO IT AND ALSO CHECK THE CIRCUIT FOR SHORTS(THOUGH IT'S A SMALL AND SIMPLE ONE).
I ADDED A SWITCH AND A PORT TO CHARGE THE BTTERY WITHOUT REMOVING IT.

AND NOW PLUG IN YOUR PHONE IN THE USB JACK AND CHECK IF IT CHARGES, IF IT DOES'T CHECK THE CIRCUIT AGAIN THERE MUST BE SOMETING WRONG IN YOUR CIRCUIT.
THE ARDUINO MAY HEAT UP BUT IT'S NORMAL(AS PER THE OFFICIAL DATASHEET OF ARDUINO UNO)

I HOUSED THIS PROJECT IN A PLASTIC BOX I FOUND LAYING AROUND.... YOU CAN USE ANYTHING AS FAR IT'S NOT CONDUCTIVE.

NOTE:- I AM NOT RESPONSIBLE FOR ANY LOSS OR DAMAGE OF YOUR PERSONAL PROPERTY CAUSED BY THIS DEVICE THAT YOU MADE JUST NOW. I HAVE TESTED THIS PROJECT AND IT IS WORKS PROPERLY.

PLEASE DO VOTE FOR ME IN THE ARDUINO CONTEST AND THE OUTDOOR SURVIVAL CONTEST!!!!