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Old 13th December 2010, 01:33 PM   #691
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Hi to all

I find at Farnell.com feritte cores, transportable in my contry and its cheap
Which of these cores can I use?

1) Multicomp 33RI 31.5x16x19
2) Multicomp 33RI 28x20x16
3) Epcos 25.3x14.8x10 material T37
4) Ferroxcube TN25/15/10-2E25
5) Ferroxcube TN32-19/13-3E25
6) Ferroxcube TX29/19/7.6-3E27
7) Ferroxcube TX32/19/15-3C90

http://www.farnell.com/datasheets/491631.pdf Datasheet for all Ferroxcube

http://www.farnell.com/datasheets/80884.pdf Datasheet for Epcos

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Old 13th December 2010, 01:41 PM   #692
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Of the Ferroxcube materials you have listed, the only one which is intended for power applications is 3C90. The rest are intended for EMI suppression filters.

Search on the web for "Soft Ferrites and Accessories". This contains the full data on Ferroxcube cores and ferrite materials, and is a very useful reference.
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Old 13th December 2010, 02:01 PM   #693
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You mean Ferroxcube TX32/19/15-3C90?

Will it be enough to 500 600W 4 ohms? How many turns for this core for 20uH coil?
its cheap 2.06 pounds

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Old 13th December 2010, 02:27 PM   #694
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Yes, but this is an ungapped Ferrite toroid (not dust-iron), so it will need a gap cutting in it to prevent magnetic saturation.

The core will be (roughly) 32mm outside diameter, 19mm inside diameter and 15mm height.

if you cut a gap in it (with a diamond coated circular tile-cutter saw) so that it had an AL of 100nH, then my estimation is that it could tolerate an i^2*L of 4mJ. As an example, a 22uH coil carrying a peak current of 13A will have a peak i^2*L of 3.7mJ.

I have never tried gapping a ferrite toroid with a tile saw, so if you did that then you would have to wind a few turns on the gapped core and measure the inductance to determine the AL for the gapped core.
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Old 13th December 2010, 02:30 PM   #695
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Actually I wouldn't try to go above 400W into 4 Ohms, with this core gapped to give an AL of 100nH.
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Old 13th December 2010, 04:54 PM   #696
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I must to gap that core? how much? Some other feritte core without gaping for 400 500w into 4 ohms?
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Old 13th December 2010, 04:58 PM   #697
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Can I use any core from here without gaping

Farnell Export

thanks
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Old 13th December 2010, 06:18 PM   #698
Pafi is offline Pafi  Hungary
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Quote:
Originally Posted by Dzony988 View Post
I must to gap that core? how much?
Summed volume of gaps should be ~100 mm^2 at least.

Quote:
Some other feritte core without gaping for 400 500w into 4 ohms?
No, it doesn't exist practically.
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Old 13th December 2010, 09:45 PM   #699
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Dzony988:
MUST USE GAP!
Buy two of these:
EPCOS|B66361G1000X187|FERRITE CORE, HALF, GAPPED, ETD34 | Farnell Magyarország
This will give you 2mm gap (170mm^3), wind it with 18 turns of multiple thin wire (as much as you can, but don't wind over gap), this will lead you to an inductor of 30uH with 43A saturation current. There is 94mm^2 winding space, and 50% effective space use (even if you wind it very nice), that means 2,5mm^2 wire-group, so if you do right the Rdc would be under 15mOhm. Should be pretty good over 500W 4 Ohm too...
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Old 13th December 2010, 10:53 PM   #700
Pafi is offline Pafi  Hungary
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Laci!

I'd rather say 28 A! I prefer higher Ae, lower Aw, since core loss is always there, but audio load is rather weak.

But this is already much better than a 106-26.
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