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I need to make a dc dc converter and have some ferrite toroids but I don't have the datasheet of the cores so I need to know how much energy are capable do store the core and what current can they handle. I need an average current of about 6A at the output so the inductor current will be at least 6A probably 7 or 8A because of the efficiency and the conversion ratio.

Edit.

What would be a good test to know if the cores I have can handle a current of 8A with a switching frequency of 10KHz?

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    \$\begingroup\$ Get some suitable cores with data. \$\endgroup\$ – Leon Heller Sep 22 '15 at 0:19
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    \$\begingroup\$ If these are really ferrite toroids, you will not be able to make an inductor with them. Ferrite has too high of permeability, and will saturate without a gap. You'll need some kind of distributed gap (low perm material) toroid, like powdered Iron or MolyPermalloy. \$\endgroup\$ – gsills Sep 22 '15 at 1:46
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    \$\begingroup\$ Very similar questions (with answers) here: electronics.stackexchange.com/questions/12594/… and electronics.stackexchange.com/questions/70604/…. My rule of the thumb is that equipment required to characterize magnetics usually costs (far) more than buying the stuff with datasheet... As for arduino project google "arduino LCR meter" etc. But it's not exactly what you want. \$\endgroup\$ – Fizz Sep 22 '15 at 2:45
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    \$\begingroup\$ Here's a paper on (laboratory grade) core characterization: core.ac.uk/download/pdf/4876634.pdf I'm not aware of any arduino-like projects that attempt something like that. \$\endgroup\$ – Fizz Sep 22 '15 at 3:11
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    \$\begingroup\$ As for measuring/estimating core losses for SMPS purposes, that's a notoriously difficult problem, see eprints.soton.ac.uk/259070/1/tmag_hys.pdf for example. I don't think there is any shoestring budget method of doing that. \$\endgroup\$ – Fizz Sep 22 '15 at 3:25

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