For a project in Engineering Design. My group and I are trying to assemble a device to charge your USB compatible cell phone through kinetic energy. In terms of our circuit this (Electronics for You-Circuit Lab- Free and tested circuit diagrams-Mobile) is what we are planning to use. The only change we are making is to replace T1( SL100) with a 2N2222A transistor we found in our Electrical Supply cabinet at school. If anyone has any advice or recommendations I would greatly appreciate any insight seeing as I'm pretty new to this.