Gapped Ferrite Inductor Calculator
Upon doing some real-world tests on an inductor i made out of an EI-33 core for a modified ATX PSU, i saw that it works just fine. Now all i have to do is buy some more wire and finish it up.
Now, i've been thinking about a fairly high-tech inductor measurement solution, which determines the real inductance with applied DC bias. However, this inductor i made works just fine, with the only measurement made was the inductance at no load, with my inductance measuring DMM. Now, it works because i provided a large enough gap. I did so without doing too much math, coz i simply did not have the math at that time. Well... after days of searching, i found the formula i was looking for. And it confirms my results. Since ferrite has a fairly sudden saturation curve, if the inductor does not saturate at maximum load, you need not worry about its inductance at max load vs its inductance at no load, because it will remain the same. Of course, apart from the minimum gap length you also have to satisfy the volts per turn criteria, but this will be in almost all cases not a problem, because the gap drastically reduces inductance, so you'll need more turns than the minimum volts/turn anyway.
Of course, i'm sharing the math with you. In the form of a convenient spreadsheet. Have fun.
Oh, and there's more goodies coming. More topologies in my SMPS Cheat Sheet, more variables to play with, compensation components calculator, an ATX PSU mod guide (wait, did i say that? oops, i spoiled the surprise). Basically more of everything. Stay tuned.
Btw. It doesn't matter whether you have a micrometer or not. A standard sheet of 80g/m^2 copy paper has a thickness of 0.1mm. Fold it and get any gap length needed. So get to work already.
Now, i've been thinking about a fairly high-tech inductor measurement solution, which determines the real inductance with applied DC bias. However, this inductor i made works just fine, with the only measurement made was the inductance at no load, with my inductance measuring DMM. Now, it works because i provided a large enough gap. I did so without doing too much math, coz i simply did not have the math at that time. Well... after days of searching, i found the formula i was looking for. And it confirms my results. Since ferrite has a fairly sudden saturation curve, if the inductor does not saturate at maximum load, you need not worry about its inductance at max load vs its inductance at no load, because it will remain the same. Of course, apart from the minimum gap length you also have to satisfy the volts per turn criteria, but this will be in almost all cases not a problem, because the gap drastically reduces inductance, so you'll need more turns than the minimum volts/turn anyway.
Of course, i'm sharing the math with you. In the form of a convenient spreadsheet. Have fun.
Oh, and there's more goodies coming. More topologies in my SMPS Cheat Sheet, more variables to play with, compensation components calculator, an ATX PSU mod guide (wait, did i say that? oops, i spoiled the surprise). Basically more of everything. Stay tuned.Btw. It doesn't matter whether you have a micrometer or not. A standard sheet of 80g/m^2 copy paper has a thickness of 0.1mm. Fold it and get any gap length needed. So get to work already.
) venture.
) I have a Corsair CX750M (Model 75-002019) that I picked up for free about 4 years ago. This is the PSU:
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