I converted a Nokia Charger to allow me to charge USB devices like iPods and iPhone.
Please use these instructions at your own risk.I would not be liable for any damage or any consequences!
My inspiration came from this information-http://www.ladyada.net/make/mintyboost/icharge.html
1) Functional Nokia Charger-1 (actually any brand will do, make sure that it works and delivers more than 500 mA of current.Check the same on the specifications of the output of device)
2) 1 USB Female type Connector
3) 7805 regulator( might not be required if the output of the charger is 4.5-5 volts)
4) A potentiometer, any value will suffice, I used 20k.
I tapped the positive and negative of the charger after opening it through wires, and checked the voltage output.The charger mentioned 5 V as output, but in reality was 8.67 volts.!! Important!! Make sure you actually measure this voltage to avoid frying your expensive device.
Once you tap the (+) and (-) of the outputs, solder the circuit according to the following diagram( One of the images)
The D+ and D- need to be both at 2 volts.Use the potentiometer to adjust this voltage. Use a multimeter to confirm this voltage is available on the pins.
After you solder, find a place where you can fit the USB connector so that you can cut out a space for the connector to come out. I used a dremel to make a clean cut.
Once done, close the cover of the charger and test again. If you plug the phone, it will automatically disconnect the ipod from charging due to insufficient current.