Ferrite beads, or commonly known as ferrite chokes are hollow cylinders that are made of ferrite materials and are used to suppress high frequency noise that are produced due to electromagnetic interference in electronic circuits. Though mostly iron oxide, ferrite beads are sometimes made out of alloys of iron. They are, then, put in plastic or rubber cases to protect the ferrite bead. Ferrite beads are found to be applicable for use in all circuits where there is production of high electromagnetic frequency noise such as cellular phones, audio players, DVDs, computers, TV tuners and so on.
Ferrite beads reduce the high frequencies by transmitting them from or to a device. For the same, a conductive cable is used which transmits the frequencies from the energy producing device or acts an antenna to receive the interferences from the devices as and when required. IN some cases, ferrite beads also act as inductors which dissipate the energy into low level heat, thereby, filtering the high interference.
Ferrite beads differ in sizes, resistance, current, impedance and several other factors associated with them; the most common ones having an impedance of 120, 220, 600 or 1000 ohm while the rated current ranged from 0.2 mA to 4000 A with 200 mA and 500 mA being the ones most commonly used.
It is, however, noteworthy that improper use of ferrite beads can be counterproductive and prove dangerous. Combining the bead with a capacitor for filtering high frequency can be one such example which can degrade the capability and efficiency of the bead. Therefore, comprehending and considering the behaviour of the ferrite bead which might vary with its types is of paramount importance before utilising the bead in any practical appliances or circuits so that the catastrophe that might follow due to ignorance might be avoided.