This .PDF document is on a Yahoo group called Radiant Energy. You may have to log on to view it. It is not a true Joule Thief because it does not conform to the conventional JT that has a single transistor with a coil that has two windings. People just can’t seem to get the terminology correct, they should call it a voltage boost converter. But the catchy JT name seems to have grabbed people’s fancy and they use it for just about any circuit that lights a LED. Which reminds me: the true conventional JT was meant to light a LED, so any circuit that does not have a LED is technically not a JT.