no worries p99, life takes precedence. In the mean time let me pontificate a bit more Ok, if the information provided on the toroid is accurate, the following can be calculated approximatly: N = sqrt( 830uH/1.48uH) = 23 turns in the primary coil (rounded down) (is this close p99? can you count the turns?) H_max = (23 turns * 0.1 amps max) / (2 * pi * 0.02 m) = 18 A/m (these are rough estimates of max current from graph, and effective radius of toroid from picture) Now look at the B-H curve below, for the 3C90 material composing the core, and notice they only show the nonlinear saturating region, and right where the chart begins, H is around 18 A/m at 25 deg temp, basicaly, this is where saturation starts. The curve below what's shown on the chart would look pretty much like vertical lines (or high u values) which I'm sure some of you have seen. So, what do you know, saturation begins at about the same number I calculated ! Guys, you can belive me or not, but the saturation characteristics of the core is what dictates the end of the ON cycle. Yes, a bit of this and that do play a part, but by far it's the saturation characteristics of the core. EM P.S. Don't be confused by the B (mT) values on the graph, the zero value corresponds to the onset of saturation and this is a relative value, referenced to B_sat, not specified explicitly.
« Last Edit: 2011-02-10, 04:45:23 by EMdevices »
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