Portable USB charger

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After a few revisions here is my latest design for a portable USB charger with replaceable batteries. More background can be found on my blog: http://mikefazz.com/MainBlog/?p=893 Instructions: Wiring - Wire a 200Ohm resistor directly onto the inner 'signal' pins of the USB plug. Some iPhones may require additional resistors to deliver the right signal for a full charge. Follow the input and output guidelines for the boost converter, making sure to mark battery polarity as the chip does not have polarity protection. Inspect the output before plugging into a device with bare wires from a usb cable. Otherwise, it can be an easy way to fry the charging chip in a cell phone... trust me. Assembly - Ensure that magnets are oriented towards each other when pushed or glued into their designated spots. I bend the spring steel around the tip of needle-nose pliers and make adjustments so they fit perfectly in their places. The connecting wire running along the side is prone to flapping, so wrap it with some tape.