FERRITE CORES Ferrite Cores are available in numerous sizes and several permeabilities. Their permeability range is from 20 to more than 15,000. They are very useful for resonant circuit applications as well as wide band transformers and they are also commonly used for RFI attenuation. We can supply sizes from 0.23 inches to 2.4 inches in outer diameter directly from stock.Ferrite toroidal cores are well suited for a variety of RF circuit applications and their relatively high permeability factors make them especially useful for high inductance values with a minimum number of turns, resulting in smaller component size.There are two basic ferrite material groups: (1) Those having a permeability range from 20 to 800 µ are of the Nickel Zinc class, and (2) those having permeabilities above 800 µ are usually of the Manganese Zinc class.The Nickel Zinc ferrite cores exhibit high volume resistivity, moderate temperature stability and high 'Q' factors for the 500 KHz to 100 MHz frequency range. They are well suited for low power, high inductance resonant circuits. Their low permeability factors make them useful for wide band transformer applications as well.The Manganese Zinc ferrites, having permeabilities above 800 µ, have fairly low volume resistivity and moderate saturation flux density. They can offer high 'Q' factors for the 1 KHz to 1 MHz frequency range. These cores are also very useful for the attenuation of unwanted RF noise signals in the frequency range of 20 MHz to 400 MHz and above.A list of Ferrite toroids, including physical dimensions, AL values, and magnetic properties will be found on the next few pages. Use the given AL value and the quation below to calculate a turn count for a specific inductance.L(mH) = A x N2 ------------ 1000000N=Number of turns, L=inductance (mh), AL=inductance index (mh)/1000 turnsTo improve voltage breakdown, coatings of ferrite cores are available for the F, J, W and H materials. Typical coatings are parylene C, Grey Coating and Black Lacquer. Parylene C coating has a thickness of 0.5 mils to 2 mils with a voltage breakdown of 750V. Grey coating has a thickness of 4 mils to 8 mils with voltage breakdown of 500V. Black Lacquer coating has a thickness of 0.5 mils to 2 mils with no increase in voltage breakdown.All items in this booklet are standard stock items and usually can be shipped immediately. Call for availability of non-stock items.For standard stocking items of Inductors, Chokes, Transformers and other wound ferrites, please see section V. For custom design of Inductors, Chokes, Transformers or Special Coil Windings, please call or fax your specifications today. provides engineering designs, prototyping and manufacturing. Low to high volume production capability with the most competitive pricing. © 1996 - 2008 Amidon.deAll Rights Reserved