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Portable USB charger
USB charger converting a single 18650 lithium ion battery to 5v 1A+ outputGadget
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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
Wiring - Wire 200Ohm resistor on the inner 'signal' pins of the USB plug.Some iphones may need extra resistors to give the right signal to perform a full charge
- Follow input and output for boost converter, make sure to mark battery polarity as the chip doesn't have polarity protection
- Check output before plugging into a device with the bare wires from a usb cable. Otherwise can be a good way to fry the charging chip in a cell phone... trust me
- Make sure magnets are oriented towards each other when pushed/glued in their spots
- I bend the spring steel around the tip of needlenose pliers then make adjustments so they fit in thier spots
- The connecting wire that goes along the side is kind of flapping in the breeze so wrap it in some tape
Materials and methods
1 - Boost Converter: DealExtreme (154870)
1 - USB Connector Type A Socket U04
6 - Magnets (1/8" x 1/4")
3 - Screws M3x60mm
3 - M3 locknut
1 - 200 Ohm resistor
6" of spring steel (mine is 0.84mm which is a bit too thick)
1 - 18650 Lithium Ion Battery (PCB protected)
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