USB charger problems

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Hi,

It's been quite some time since I've visited this site, since I kind of lost temporary interest in my electronics projects (some of which still aren't finished after 4 years, but oh, well, they'll get finished eventually).

There's one circuit however, that I'd really like to work, and well, it isn't working...

It's simple enough: two 5 volt outputs on 1 PCB (2 regulators), each one going to a USB connector. Both have a LED indicating if more than 100mA is being drawn from the output. I'd use this to load my iPod when there isn't a PC available (or load 2 at the same time, like I tried on the last skiing vacation). Sounds simple enough, right?

Well, first of all, here's the circuit with some more explanation: http://members.lycos.nl/anthonyvh/index.php?page=usb-charge.

This is what it's (not) doing: when tested with a modified USB cable, the circuit will deliver 280mA without a problem and the LED burns (haven't tested with higher values). The output is roughly 5V (a bit less because of the shunt resistor necessary to control the LED). However, when I plug in my iPod, the LED lights up for about 1/10th of a second and then it goes out. Nothing happens, no loading animations on my iPod, nothing.

Has anyone got any idea why this is? The iPod's working just fine, I can load it from my PC with both USB & FireWire, so well, I just don't get how this won't work.

Regards, Anthony
 
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