Ferrite beads, also known as ferrite chokes or cores are nothing but passive electronic components that helps to reduce noise in electronic circuits. Cables consisting of ferrite beads can attenuate or reduce the impact of undesired electromagnetic interference (EMI) generated by circuits and devices. Manufactured from black semi-magnetic materials, iron oxide, and a host of other materials, ferrite cores provide maximum shielding efficiency. However, you will require a plastic or rubber material to keep the cable ferrites at the right position. These products are designed to protect your devices and appliances from unwanted EMI emanating from two directions. Ferrite chokes will not only suppress interference from a particular device or circuit but also reduce harmful radiations coming towards it. If you are interested in using Ferrite materials for EMI shielding purpose, keep the following points in mind:
More the Better
When you use more ferrite chokes in a single cable, it produces more EMI resistance. The beads help contain the magnetic field regardless of whether the beads are in contact with the cable or not. When you use them in an inductor, they serve as EMI filters and protect your electronic circuits and devices from the noise and high-frequency radio frequency interference (RFI). The energy impeded moves up the cable or loses strength at the bottom as heat. However, there may be complications if the heat generated in the process exceeds the Curie point. Such extreme heat affects the ferrite choke’s magnetic properties, and it stops attenuating EMI or noise.
Small but Effective
These materials are small and allow not more than one turn — the time a cable passes through the hole of a bead. However, if you want more than one turn, you can use toroidal beads that come with bigger holes. EMI product manufacturers prefer the use of these products when they require stronger impedance. It is easy to keep a note of the turns when an electrical cable passes via the center hole of the ferrite choke. The level of resistance may differ depending on what type of turning method or process you use. You can bend or twist the cable in a clockwise, anticlockwise, or in a zigzag pattern. The turning or twisting technique goes a long way in minimizing the interference. That is because the method has a direct bearing on the level of impedance generated by the ferrite chokes.
Ferrite Beads Come in Many Forms
A variety of ferrite beads are available in the market. They are categorized by enclosure size, measurements, type of packaging, resistance to DC, impedance, rated current, and the range of operating temperatures. The commonly used sizes are 120, 220, and 600 Ω with resistance level up to 2.70 kΩ. As far as the rated current is concerned, it may vary between 0.2 mA and 4000 mA. You may also find ferrite chokes with a rated current of 500 mA or 200 mA.
Varying Electrical Resistance
The impedance of ferrite beads depends on factors such as the size of the ferrites, kind of the material, and the level of the radio frequency. When there is a high-frequency level, the ferrite chokes can reduce EMI in low-level reactance form. And with low-level reactance, the possibility of resonance is low, which has a negative effect on reducing EMI. The resistance power of the beads is directly proportional to the length. In fact, you can use long and protracted beads in external cables. The smaller ferrite beads, on the other hand, can be used in electrical goods in the circuits on conductors. Alternatively, you can also use the smaller beads around the pins used in circuit board conductors.
Multiple Uses
Ferrite beads are used in TV tuners, smartphones, digital photo frames, computers, laptops, audio systems, game machines, speakers, and DVDs to reduce or get rid of unwanted noise in the power cables of these devices.
Choose first-rate cable ferrite beads to remove interference in devices and applications. You must get in touch with reputed ferrite suppliers near you who will help you with the selection of the right-sized materials, their frequency, impedance, and their ability to cut back on EMI or RFI.
Author Bio:
Irene Simpson is an author and a web enthusiast, who loves to write on various technology and electronics related topics. However, her primary interest lies in electronic enclosures, cable ferrite and conductive silicones for gaskets. She thinks it’s impotant to protect electronic devices from unwanted interference and hence, offers tips on choosing the right EMI shielding material for electronic devices.
