In any type of use in electronics, a choke refers to an inductor that is used to allow direct current to pass through the choke while blocking the alternating current or AC. This is done by a series of coils of magnetic wire over a magnetic core, but some can also be on a toroidal shape, which is more like a donut.
While the term block may have been more effective than the term choke, it is still a very clear picture of what is happening in the component regardless of its specific type. The common mode choke, however, is a bit different than either radio frequency chokes or audio frequency chokes in its design.
The Basics Design
The simple design of a common mode choke makes it an easy to identify type of component. It will have two different coils that are wound in opposite directions around a common core, or the common single mode. In essence, they cancel each other out through a process known as cross-cancelling.
There are also some types of common mode chokes that may have more than just the two windings. This will depend on the specific requirements for the choke. The amount of noise suppression through the system will vary based on the way the windings are placed on the common core.
The various windings on the choke as well as the size of the core will allow for different uses, including fully blocking even large amounts of high frequency based on the input to the system. Remember, this is a passive element in the system since it doesn’t require any action to create the blocking action, rather it is the result of the field that builds up around the core that creates the blocking ability.
The Uses
Depending on the specific design of the common mode choke they can be used in a wide variety of different electronics and system components. You will find them in personal computers and Ethernet and USB lines for computers and peripheral devices as well as for LCD panels.
They are also commonly found in a wide variety of electronic devices including audio and visual equipment and in several different types of industrial and manufacturing equipment systems.
Each design and type of these devices will offer more or less noise suppression, and it will be essential to choose a choke that will successfully eliminate the desired common mode noise.
