Very simple micro power step up booster (joule thief) without using resistor - operating at minimum voltage source of 250 mV. The circuit main driver is the transistor N851 and toroid inductor rated at 8.3 mH each winding (2 winding in one toroid core). If the circuit is tested on proper circuit board instead of the breadboard it should be able to light up the LED at 200 mV.
It's not a voltage boost circuit but rather current boost between the Emitter and Collector or the Based and Collector. The maximum peak oscillation is at 600 to 650 mV not even 1 volt.
Micro-power energy harvesting (wind, radio signal rf, solar, piezo, etc)
MY APOLOGY THERE IS MISTAKE IN THE DIAGRAM LED NEGATIVE SHOULD CONNECT TO E (EMITTER) AND POSITIVE COLLECTOR (C)