Dave Clausen of NYC Resistor wanted a powerful battery pack to recharge his energy-hungry iPhone 3GS and myriad ham radio equipment, so he designed the Mintybuck to handle the job with ease. Rather than using AA batteries and a boost converter to raise the output voltage to 5v, he swapped in a 12v lithium cell and a LM2674-5.0-based buck converter to efficiently drop the voltage down to 5v. The chip is spec’d for 500 mA, and can convert power with >90% efficiency. Not bad for a little charger!

  • knoxster

    dont take it on a plane train or bus…..haha unless you just like being harassed by the FBI….;-] very cool charger even if it looks like a bomb.

  • MadRat

    Uh-oh, looks like Becky Stern might have some competition.

    • Becky Stern

      Competition in what field, exactly? =]

  • ksr

    any thoughts if this will work with an ipad

    • Matt Mets

      According to mymobile911 (, the iPad requires a 1-2A source to charge correctly, so my guess is that this circuit isn’t going to cut it. However, it should be possible to find a beefier buck converter chip that would work.