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  • Build Your Own 1-Amp iDevice Charger
    [ame=http://vimeo.com/13835359]Reverse engineering Apple's secret charging methods on Vimeo[/ame]


    The engineer/artist/hacker behind the Minty Boost do-it-yourself USB recharger has figured out Apple's weird and arcane way of identifying which chargers are "supported" or not, allowing any reasonably talented modder to make their own 1-amp recharger for iPhones or anything that uses USB to charge. The technical analysis on the Minty Boost site is probably interesting only to serious wireheads; the video above explains it even more succinctly. By taking apart Apple's charger as well as a third-party battery-powered recharger, Limor "ladyada" Fried found out that supported chargers just clip different sized resistors on the USB data lines.

    Using the first Minty Boost instructions and kits, hobbyists found that newer devices simply displayed the "charger not supported" warning and wouldn't charge. Looking into this, ladyada took into account that smarter USB devices will alert the computer or charger that they are about to draw current in excess of the 500 mA limit of standard USB. Most dumb devices don't do that, though, and ladyada figured that chargers were going to generally not be too smart. So she tore apart chargers for different Apple devices and found that the resistors were placed on the data lines to limit voltage to 2.8V on one line and 2V on the other. Using the same setup on a Minty, it drew 1A immediately. Experimenting further with a TuneJuice battery backup from Griffin, she found resistors limiting voltage to 2V on both lines when she tore that one apart. This forces the iDevice to draw only 500 mA, a much more reasonable draw for the AAA batteries used in the TuneJuice.

    This information was previously available only to charger manufacturers who had signed Apple's restrictive non-disclosure agreement. Hobbyists and smaller manufacturers are now free to make more powerful chargers, and iDevice owners can look forward to an end to the annoying "charging is not supported with this accessory" messages.

    Source: Engadget
    This article was originally published in forum thread: Build Your Own 1-Amp iDevice Charger started by Paul Daniel Ash View original post
    Comments 38 Comments
    1. Cowboy's Avatar
      Cowboy -
      Very nice!
    1. llj143's Avatar
      llj143 -
      good stuff ^^
    1. tremerone's Avatar
      tremerone -
      I was jailbreakin iPhones and touches and there were a few with apples stock charger wire that still gave off the charging is not supported message! Very peculiar!
    1. FoneWeasel's Avatar
      FoneWeasel -
      They don't actually show you how to build it. They just go over the resistance required for a .5A charger. Watched the video the other day.
    1. plumoso's Avatar
      plumoso -
      Zzzzzzzzzzzxzzzxzzzzzzzzzzzzz
    1. whereswaldo's Avatar
      whereswaldo -
      Smart
    1. FlyingJoey's Avatar
      FlyingJoey -
      Very interesting to see a broad talking about amps and current and geeky sh!t.
    1. Bassface's Avatar
      Bassface -
      Now that we have this formula, couldn't we theoretically create our own external hardware? Other than chargers?
    1. gautam's Avatar
      gautam -
      great info .. will try in my free time
    1. BeachLivin88's Avatar
      BeachLivin88 -
      Very interesting, however she could have been a little less redundant. Cut that video time in half.
    1. T4R06's Avatar
      T4R06 -
      waste of time
    1. vinaygoel2000's Avatar
      vinaygoel2000 -
      Quote Originally Posted by FlyingJoey View Post
      Very interesting to see a broad talking about amps and current and geeky sh!t.
      Come on man. You cud have said "lady". U wud have saved urself a letter and gave due respect to her.
    1. nkgneto's Avatar
      nkgneto -
      Quote Originally Posted by FoneWeasel View Post
      They don't actually show you how to build it. They just go over the resistance required for a .5A charger. Watched the video the other day.
      Minty Boost! - USB charger for your gadgets


      step by step solder process
      MintyBoost

      Buy the kit $19.50

      MintyBoost Kit [v3.0] ID: 14 - $19.50 : Adafruit Industries, Unique & fun DIY electronics and kits
    1. hapishyguy's Avatar
      hapishyguy -
      Tell me something new. In India every guy in the street corner does that lolz! But its nice that someone actually cared to make a video and post it.
    1. quidam_brujah's Avatar
      quidam_brujah -
      Quote Originally Posted by FlyingJoey View Post
      Very interesting to see a broad talking about amps and current and geeky sh!t.
      Wow. [SARCASM]That wasn't sexist.[/SARCASM]

      At least you coulda gone with 'dame'.
    1. tudtran's Avatar
      tudtran -
      Nerd is always turn me on ;-)
    1. severe's Avatar
      severe -
      Informative and fun presentation.

      Why must everyone be so critical? My guess is she didn't create this video to be judged. Wotta bunch of a**holes some of you are.

      The Internet, such a lovely place.
    1. Antman217's Avatar
      Antman217 -
      Pretty cool but they dont actually show you how to build one and buying all that equipment will cost way more than just buying an iphone charger
    1. Bluemoldycheeze88's Avatar
      Bluemoldycheeze88 -
      Quote Originally Posted by FlyingJoey View Post
      Very interesting to see a broad talking about amps and current and geeky sh!t.
      lawl
    1. ruben00's Avatar
      ruben00 -
      This is cool, if you have one of those old head units in your car with the Ipod interface, you can now update it to charge your iphone 3gs