USB Charger Hack

From Mexico.purplecow.org

Revision as of 05:29, 11 March 2011

Cheap USB charging devices only provide a +5VDC rail. Nothing on the data lines - not connected. This works for a lot of things, but my Motorola Milestone and iPod won't charge because they expect to see some life on the data lines.

I had a quick Google and found a number of solutions, of which this was the simplest.

                    +5VDC
                    |
                    |
               +----+----+
               \         \
          150k /         / 50k
               \         \
               /         /
      USB D- --+         +-- USB D-
               \         \
          100k /         / 50k
               \         \
               /         /
               +----+----+
                    |
                    |
                   GND

Of course, I didn't have any 50k or 150k resistors in my junque box, so I subbed 47ks in. Still works just fine. Both iPod and Milestone charge away nicely.

I've been told this won't work for the iPhone 3G or newer because they're _really_ fussy about the voltages they expect. I'm not too fussed since I'm unlikely to buy an iPhone.

Credit where credit is due: I looked at a quite a few ideas while poking around with this, but this link was the most obvious and clear: http://tzywen.com/modules.php?name=News&file=article&sid=683

(I'm stashing this note here because I don't trust forums to be here in the future.)