Intro: Portable USB Charger
Does your iPod run out on you all the time?
Well, i have a soulution for you!
This USB charger utilises 2 standard cellphone batteries to charge your iPod, much more storage than a usual USB charger.
N.B. To construct this project, you will need a mild understanding about electronics, how to read schematics, solder etc.
I am not liable for any damage that may occur to your iPod from using this project.
Li-ion batteries can be potentially dangerous. Handle them with care and NEVER short-circuit.
Step 1: Parts & Tools
You will need:
2 Nokia (or equivalent) Cellphone batteries
1 DPDT slider switch
1 7805 regulator
1 Small heatsink
1 Female USB connecter
1 330 Ohm Resistor
1 Small red LED
A box to put it in (I used a small DickSmith one)
1 Small set of male/female connectors (I used old style nokia charger M/F connectors)
Lots of small wires
4 47k resistors (optional)
Soldering iron and solder
Step 2: Schematic
Here is a Schematic on the circuit.
Step 3: How It Works
When the switch is in the 'internal battery charge' position the 2 batteries are in parallel, so they can be charged together by the 5v power source.
When the switch is in the other position the 2 batteries are in series, with a total voltage output of about 7-8v. This then feeds the 5v regulator (the 7805) which puts the voltage down to 5v.
Step 4: Putting It Together
Since the first and only one of these chargers I made is compactly glued and taped into its box I cant really go step by step putting it together with pictures but i will try my best to explain it :)
Start by trying to fit all of the components in the box. Drill all the necessary holes and slats and make sure that there is no rough bits. As you can see in the picture, it's pretty compact.
After you've confirmed that everything will fit, solder the batteries to the switch and the input connector, then solder on the 7805, the led, resistor and the female USB port (look at last step for how to achieve a biased voltage into the data pins). Bolt the 7805 to the heatsink, then fit it all back in the box nice and snug, making sure that there are no loose connections, shorts and that all the solder joints are insulated.
Step 5: Tips
I mounted the Led and resistor on top of the 7805, and put this near the edge so that i could just drill a hole and poke the Led through.
Before you finally put the 'guts' of this project in its box, test it just to make sure that it works, so that if there is any faults you dont have to disassemble it.
You might be thinking "Omg it is so dodgy to chage Li-ion Batteries without proper charging circiuts!" Yes, it is very dangerous, but i had a peek under the top cover of the Nokia batteries, and turns out that there are inbuilt charging circuits! They even have little solder taps which are perfect to solder wires to for this project.
In the form i just described to you, this will most likely not charge an iPod Touch or any of the newer iPods. This is because you need a couple of volts going into the data pins of the USB connector. Look at the picture for how to do this.
Please vote for me in the USB Contest :)