What kind of a toroid (specifically) do you need to make a joule thief? Answered
I've literally looked everywhere for what kind of a toroid you need for a joule thief, but no one gives a specific number range or type; the most specific was, "high permeability ferrite toroid". I've been searching high and low for a reasonably priced (including shipping) high permeability toroid for over a week, and I've ended up empty-handed. What's considered "high" permeability?
The best one within my price range seems to be a pack of FT50A-75 toroids that I found on eBay. I looked up the specs:
Inner Diameter: 0.312 inches
Outer Diameter: 0.500 inches
Height: 0.250 inches
AL Value: 3000 µH/100 turns
Which would be 300nH per single turn?
Is that high or low permeability? Will it work on a joule thief?
Am I making a mountain out of a mole hill? Can I just buy the cheapest ones I can find on eBay? (Even though the seller even specified "low permeability" in the description?)
And I don't have any old electronics that I could try to take apart to salvage it from.
Please don't say to just buy it and try it... It's about 6 bucks, but I'm in a situation where I really need to save every dollar I can. I really can't afford to just spend money on something that might not work. If it doesn't work - and I'm usually unlucky, so we can assume that it won't - I'll have to buy more, for probably a more expensive price, and that's more money that I just can't risk. Money is a big factor, so what's the cheapest toroid that I can get?