So I bet you have seen these USB Battery Packs that recharge phones and the like. I thought I should be able to use one to power a USB powered device other than just charge a phone. I got a USB to 3.5 mm cable and tried to run a digital picture frame and a wireless camera. I tested voltage on the 3.5 mm jack and see ~5.04 VDC with proper polarity (outside barrel negative, inside positive). The power pack has two USB sockets, one labeled 1A and the other 2A. Neither of the two devices tested with the setup showed any signs of life when connected and both had a documented current draw under 1.5 A. I tried both the 1A and 2A sockets on the power pack. Everything works fine with the appropriate 110 VAC adapter. What am I missing here?