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FRM21/4/12
| Stan Zurek, FRM21/4/12, Encyclopedia Magnetica, E-Magnetica.pl |
| reviewed by Jeanete Leicht, 2014-01-21 |
FRM21/4/12 (also FRM21-4-12 or FRM 21 x 4 x 12) - a type of frame core made of soft ferrite, supplied by Ferroxcube.1)
The numbers refer to the dimensions of the frame in millimetres, so 21 = 21 mm, etc.
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The core comprises a cuboid bar, which slides into a bobbin. The outer frame of the core is assembled on top of the bobbin.
The bar has a symbol BAR22/2/6 (or BAR22-2-6). The bar is marked with “22” because it is slightly longer (21.8 +/- 0.3 mm).
The relative winding width is longer than in most of other ferrite cores, which allows for the bobbin to have multiple sections. The manufacturer offers the multiple-chamber bobbin, but there is no indication of how all the parts should be held together (e.g. a clip).
As of 2013 the core was offered in two materials: 3C90 and 3C91.
Images
S. Zurek, E-Magnetica.pl, CC-BY-4.0
Core parameters
The table below lists the core set parameters as given by Ferroxcube.2)
| Symbol | Parameter | Value |
|---|---|---|
| Σ(l/A) | core factor | 5.06 mm-1 |
| Ve | effective volume | 312 mm |
| le | effective length | 40 mm |
| Ae | effective area | 7.9 mm2 |
| Amin | minimum area | 5.7 mm2 |
| m | mass of frame | 1.5 g |
| m | mass of bar | 1.0 g |
The values were measured for frame with a bar core, without an air gap.3)
| Material grade | AL value | effective permeability μe |
|---|---|---|
| 3C90 | 400 nH +/- 20% | 1610 |
| 3C91 | 470 nH +/- 20% | 1890 |
Data sheets
Ferrite core FRM21/4/12 Ferroxcube
Copyrights © Ferroxcube
See also
References
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