Other Projects > USB Battery Charger

Why this project?
USB Battery Charger

I have needed one of these for a while. I am using my cell phone more and nothing is more annoying than it running out of juice. So, I had seen these all over the internet and decided on a schematic that I saw on Jameco's web site. You can see thier project here.

Note and Disclaimer: Soldering irons get hot. If you solder enough, or not carefully enough, you will get burned. Oh, and wear eye protection! And if something blows up, it isn't my fault. It is the Nac Mac Feegles! Test, then test again.

The circuit is based around the 5V regulator and it is quite similar to my 5 Volt Regulator project. If you want more details on the 7805, you can read about it on the 5 Volt Regulator project page. You can find the datasheet for the 7805 here.

As is my custom, I have drawn up the schematics in Diptrace and you can download them here. I ended up using a higher voltage LED than was orginally specified by the schematic. I used a 5V LED with a 75 ohm resistor. So, if you change it, be sure to change the resistor to make the LED bright enough to see. The trickiest bit was to make it fit within approximately one inch square. I used my Toner Transfer Method to make the PCB.

The author of the article (Phil Tang) stated that he based all of his voltages off of his iPhone charger. I figured that it would be pretty close to my LG phone. I took a USB cable from an old mouse and checked out my USB wall chager and it was almost exactly what he stated in his article.USB Plug The finished charger works great on my LG phone.

Pin 1 is the +5V (Red), Pin 2 should have right at +2V, Pin 3 should have +2.5 (approx.) and Pin 4 is ground (Black) - All voltages approximate.


Toner Transfer Done
Toner transfer is done. No room for intials or dates even!
Finished USB Charger
Lid is closed
USB end
USB end of the charger. I put a little duct tape around the cut metal to cover the sharp edges. And they are still sharp after filing!
Open Boost
All opened up. The heat sink from the 5V regulator touches the lid. It is pretty compact in there.

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