How many windings do I need on a toroid to make a joule thief work?

How many windings do I need on a toroid to make a joule thief work? Is there a min and or max number of winding? Is the toroid acting as a one-to-one transformer? Can I use anything as the iron core? Is there a calculation to find this out? Thanks for any help.

Re-design8 years ago
Try 8 to 11 turns.