a big transformer ive had that came from an old receiver. it had 3 windings.
im using 2 of the windings, 1 winding that has a center tap im using for a joule thief oscillator, and the 2nd winding is the flyback winding im using to power AC devices and to rectify for DC charging.
my joule thief windings have 1.4ohms between the center splice and the flyback winding is 3.9ohms.
a 10 ohm 10 watt resistor is used in series with the 5k pot to help prevent instantly burning it out if no load is connected, but i only need the 10 ohm if im routing the pot through a base resistance of less than 4.7kohms.
in this video the input is a 12v 1A adapter (roughly 12.5v 1.5A at most) and the circuit is consuming a maximum of 480mA at 12v
drawing of how the circuit is wired - http://i906.photobucket.com/albums/ac269/magneticitist/hpjt.png