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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
Parts List
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.
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
Parts List
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.
In most cases, the circuit will work fine without the caps, but I have come across a couple of occasions where a circuit failed to work because the voltage regulator lacked the recommended stabilisation caps.
Also, you don't need a potentiometer to get the 2V for the data lines - just use a 75k resistor from data to +5V and and 49.9k resistor from data to GND (0V) as shown on ladyada's site. The two resistors will be both cheaper and smaller than the poti.
And yet another hint from ladyada's site: If your wall plug is capable of supplying 1A of current (and you provide sufficient cooling for the voltage regulator), you can put 2.8V on the D- line and 2.0V on the D+ line, thus making your iPod/iPhone charge at twice the current and therefore twice the speed.
The space inside the Nokia charger was very limited, to the point where I have squeezed all stuff as far as possible.I dont think I would have had space for a capacitor.
I chose the potentiometer because, the resistors I had with me were not of correct values.It was a Sunday, when I made this charger hack, and most electronic supplies stores are closed on Sundays.I had the spare potentiometer with me, which was lying around since a very long time.
If I would have made the resistor network so that the charger can supply 1AMP, then I would have probably fried the 7805.I would need a heat sink on the 7805, and as mentioned above, I do not have enough space for the same.