'Dead bug' 3V iPod charger

Based on Ladyada's design (v1.2)

June 12 2007
Just finished building an AA-battery iPod charger, by the excellent design of Ladyada's. I found I could fit mine comfortably within the battery house of an IKEA christmas light thingie. This holds 4 AA batteries, so it had plenty of space. The female USB connector is from a USB->USB extension cable,
which came with a memory stick I bought. I opted not to etch a PCB, to save time + space. The "soldering-together-components" scheme is something I picked up from M. Tilden's excellent robot book; Junkbots, Bugbots & Bots on Wheels.


Anyway, just a few thoughts: I assumed the wiring in the USB cable I used was straight-forward, and that the red cable was +5V, and the black one GND. HOWEVER, connecting the iPod to this, sent it straight into a coma -- fortunately, it just rebooted and came back on. It seems the cable I'm using has +5V on the black, and GND at red... for some reason. I checked this by plugging the other half (male end) of the cable into my PC, and simply measuring the red/black wires using a voltmeter (which showed -5V when I had things the wrong way). After simply desoldering and swapping the wires on my circuit, and pulling the data lines high (3V), the charger seems to work finally works!
Still, the importance of checking the USB wiring should be stressed in the instructable, if it's not already... This can kill your iPod - I must've been lucky!

Also, I notice on the (version 1) Eagle schematic, she's labelled C1 and C4 as 1uF, which should read 0.1uF.

Old version (please bear with the crummy soldering...)

Updated version v1.2. Note that the legs on the MAX756 can only be bent twice, before they break off! Still, it's possible to solder components to the stump, but it's a fragile joint (yes, LBI snapped in my case).



Debugging Notes

June 12 2007
Version 1.2: It seems the newer generation iPods need the data lines to be tied to 3V (or GND, depending on the model, apparently). By adding some resistors, the circuit finally works! Also, there's the nifty LED, which (as I understand) lights up when the batteries need to be changed. Or does it light when the iPod is charging? Not sure. In my case, it turns on when the iPod charges, but maybe the batteries are just old? Recommend browsing through ladyada.net, especially the forum. Lots of great info there!
June 8 2007
After I finished building, I checked with the voltmeter that the 3V from the batteries is in fact transformed into 5V. When I connect my iPod nano, the battery icon changes to the "lightning icon," and the green background (in the icon) blinks, which seems to indicate that it's charging.
However, after a while, the icon goes back to normal battery, and when I unplug the iPod, I can't see that the battery level has increased at all... Granted, the AA batteries are not fresh out da box, but I expected the design to be quite energy efficient. Or do I always need spanking new batteries to charge? OR, obviously, there's something wrong with my build.


 - Joakim



This page is my private stuff, and not affiliated with the University of Bergen. Any hacks and cracks to your iPod is at your own risk.