Ferrite cores are used in electronics in transformers, inductors and electromagnets. They are made with ferrite, a ceramic compound that contains iron oxide. Ferrite cores reduce or eliminate the electromagnetic interference that originates with electronic and electrical equipment, both preventing equipment from broadcasting interference and protecting it from incoming interference.
Ferrites are divided into soft ferrites and hard ferrites, which refers to their magnetic properties and not their physical properties. Ferrite cores are made from soft ferrite materials that may include manganese, magnesium, nickel and zinc. These ingredients are mixed with iron oxide and pressed into shape and then fired in a kiln to produce a ceramic. Ferrite cores are used in inductors, commonly called chokes, which block alternating current while allowing direct current to pass. A choke prevents the wires in an electronic device from acting as an antenna.
Ferrite cores are frequently used as ferrite beads. These cylindrical beads can be found on USB cables and audio and video cables and consist of one or more coils of wire wrapped around a ferrite core and then coated with a plastic shell. To use a ferrite core, you can purchase electronics cables that already have ferrite beads or attach a third-party ferrite core to your cable. Ferrite snap beads for audio and video come in plastic-coated tubes that open on the side like a clam shell. You can simply clamp these onto your existing cables. Other types of ferrite beads include toroids (a donut shape) and tubes.