Magnetic Core

 A magnetic core is a piece of magnetic material with high magnetic permeability, used to confine and guide magnetic fields in various electrical and electromechanical devices. Here are some key points about magnetic cores:

• Materials: Common materials for magnetic cores include iron, silicon steel, and ferrites.

• Applications: Magnetic cores are used in transformers, inductors, electric motors, generators, loudspeakers, and magnetic recording heads.

• Function: They provide an easy path for magnetic flux, facilitating flux linkage between different parts of a magnetic circuit.

Iron Powder Cores are made in numerous shapes and sizes: such as Toroidal Cores, E-cores, Shielded Coil Forms, Sleeves etc., each of which is available in many different materials. There are two basic groups of iron powder material: 

(1) The Carbonyl Iron and, (2) The Hydrogen Reduced Iron. 

 The Carbonyl Iron cores are especially noted for their stability over a wide range of temperatures and flux levels. Their permeability range is from less than 3 u to 35 u and can offer excellent 'Q' factors from 50 KHz to 200 MHz. They are ideally suited for a variety of RF applications where good stability and good 'Q' are essential. Also, they are very much in demand for broadband inductors , especially where high power is concerned. The Hydrogen Reduced Iron cores have higher permeabilities ranging from 35 /J-, to 90 /v,. Somewhat lower 'Q' can be expected from this group of cores. They are mainly used for EMI filters and low frequency chokes. They are also very much in demand for input and output filters for switched mode power supplies.

The toroidal cores are the most efficient of any core configuration. They are highly self-shielding since most of the flux lines are contained within the core. The flux lines are essentially uniform over the entire length of the magnetic path and consequently stray magnetic fields wil l have very little effect on a toroidal inductor. It is seldom necessary to shield a toroidal inductor. 

MATERIAL #0 (u=1): Most commonly used for frequencies above 100 MHz. Available in toroidal form only. Note: Due to the nature of this material the inductance resulting from the use of the given AL value may not be as accurate as we would like. Inductance vs. number of turns will vary greatly depending upon the winding technique. 

MATERIAL #1 (u=20): A Carbonyl 'C' material, very similar to material #3 except that it has higher volume resistivity and better stability. Available in toroidal form and shielded coil form. 

 MATERIAL #2 (u= 10): A Carbonyl 'E' iron powder material having high volume resistivity. Offers high 'Q' for the 2 MHz to 30 MHz. frequency range. Available in toroidal form and shielded coil form. 

 MATERIAL #3(u=35): A carbony l 'HP' material having excellent stability and good 'Q' for the lower frequencies from 50 KHz. to 500 KHz. Available in toroidal form and shielded coil form. 

 MATERIAL #6 (u=8): A carbonyl 'SF' material. Offers very good 'Q' and temperature stability for the 20 MHz to 50 MHz frequency range. Available in both toroidal form and shielded coil form.

 MATERIAL #7 (u=9): A carbonyl 'TH' material. Very similar to the #2 and #6 materials but offers better temperature stability than either. Available in both toroidal form and shielded coil form. Frequency ranges from 5 MHz to 35 MHz.

 MATERIAL #10 (u= 6): A powdered iron 'W' material. Offers good 'Q' and high stability for frequencies from 40 MHz to 100 MHz. Available in toroidal form and shielded coil form.

MATERIAL #12 (u=4): A synthetic oxide material which provides good 'Q' and moderate stability for frequencies from 50 MHz to 200 MHz. If high 'Q' is of prime importance this material is a good choice. If stability is of a prime importance, consider the #17 material. The #12 material is available in all sizes up to T-94, in toroidal form. Not available in shielded coil form. 

 MATERIAL #15 (u=25): A carbonyl 'GS6' material. Has excellent stability and good 'Q'. A good choice for commercial broadcast frequencies where goo d 'Q' and stability are essential. Available in toroidal form only. 

 MATERIAL #17 (u=4): This is a new carbonyl material which is very similar to the #12 material except that it has better temperature stability . However, as compared to the #12 material, there is a slight Q' loss of about 10 % from 50 MHz to 100 MHz. Above 100 MHz, the 'Q' will gradually deteriorate to approximately 20% lower. It is available in both toroidal form and the shielded coil form. 

 MATERIAL #26 (u=75): ' ' A Hydrogen Reduced material. Has highest permeability of all of the iron powder materials. Used for EMI filters and DC chokes. The #26 is very similar to the older #41 material but can provide an extended frequency range.