This modified version of 1V-LED driver @faceblast works from 0.5V up to 3V (solar element or bicycle's dynamo mashine) and provide current for an accumulator (lamp in the circuit is equivalent load). 500 mOhm resistor emulates internal resistance of the supply source, two 500 Ohm resistors forms bootstrap to stabilize frequency and to start animation. In real scheme all depends on transformer's magnetic properties, saturation voltage of transistor and weather in your country.
