[Ladyada] has been hard at work reverse engineering the charging method used by Apple products. This saga takes us through the years as new devices were released and subsequently broke Minty Boost’s charging capabilities. It seems the data lines were gradually adopted as a means for iPhones and iPods to identify the charger that had been connected. By adding voltage dividers to the D+ and D- lines you can instruct the handheld to pull 1 Amp (with data voltages of 2.8v and 2.0v) for wall chargers or 0.5 Amps (2.0v on both data lines) for portable chargers. In the video above [Ladyada] removes the surface mount resistors from a commercial charger in order to measure the voltage divider and discover the secret.
[Meseta] built a powerful boost charger to top off his portable devices. He was inspired by the Minty Boost but wanted to overcome the rather limited capacity provided by the two-celled product. He ended up building his own DC to DC boost circuit rather than using an all-in-one IC. As you can see, the result uses four 18650 lithium-ion cells, normally found in laptop batteries, and can power two USB devices at the same time.
The team at oomlout has continued to post all the methods they use in their manufacturing process. This time around it’s the kitting process: how they actually packaged 30 identical SERB kits in an efficient fashion. We covered their wire cutting bot before, but they’ve got other dedicated machines like a sticker cutter. The stickers are used to remove all the cut acrylic pieces from the laser cutter as one unit. They’ve got some other tricks like using a scale to count bolt quantities, and an egg timer to keep track of the laser cutting. All of their envelopes are printed using a parallel port inkjet that has been modified to work with any thickness paper.
We love when hackers bother to post this much detail about their process. One of our favorites is [ladyada]’s full rundown of how the Minty Boost was created.