The Basics Of A Common Mode Choke

by | Jan 17, 2017 | Electronics and Electrical

When it comes to magnetic components in systems, the simple designs are often the most effective and efficient. The common mode choke, which is a type of inductor, is a passive element that is designed to filter certain frequencies and electromagnetic interference. This is usually the high frequencies, allowing the lower frequencies to pass through the component.

A Description

The basic design of the common mode choke is a single and simple toroidal core which looks like a donut. There are two different windings around this core. The core itself can be large or small and it is typically made of a ferromagnetic core.

The windings, which are usually copper wire, will be identical on either side of the toroidal shape. This creates a balance or symmetry to the component that is essential. However, each of the windings runs in an opposite direction, so the sides or halves of the choke are really a mirror image of each other.

One side is designated as the primary winding and will be attached to the current coming into the system, usually from the AC main. The secondary coil will attach to the neutral line and as the mirror image, will work to cancel out the noise or the interference.

There are some types of common mode choke designs that include more than just two winding. As with all types of inductors, the configuration of the windings will have an impact on the different types of radio frequency or electromagnetic interference that is removed.

Common Uses

These components are found in virtually all electronic systems. This includes use in computers, telecommunication systems and even with other types of electronic devices. LCD panels will also use common mode chokes as will most audio and video equipment on the market today.

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