A Simple Explanation Of Toroidal Inductors

For anyone just learning about electronic circuits for any type of hobby or specific repair job, prototype development, or just for curiosity, one of the first things you will see and recognize are toroidal inductors.

These are easy to spot because of their unique shape and design, although are a lot of different options as well. Often you will see toroidal inductors listed as chokes, which is based on their actual action in the circuit. They are typically used with low frequencies to allow for a large induction which will be a function of the rate of change in the current.

All types of inductors are passive, which means they do not act on the current, but rather the current acts on them. They use magnetism as the method for both the storage as well as the release of the electrical charge.

The Shape

When you are looking for toroidal inductors in an electronic device, they will be easy to see. They are donut shaped components which are wrapped with wire. Typically the donut-shape is made out of a ferrite or powdered iron, but there are other possibilities as well.

Around this circular core, the wire is wrapped either in infrequent wraps or very tightly wrapped depending on the specific size and use of the component. The shape and the wrappings are very important as they actually help to reduce the EMI or electromagnetic interference that can “leak” from other types of inducers.

In addition, they are designed with what is known as a closed loop design, which is very different than a linear design. With the hollow center and the closed loop, it is possible for toroidal inductors to be smaller while also creating a more powerful magnetic field, which is critical in electronic devices where space and EMI prevention are critical in the design and operation.

The Windings

Different toroidal inductors will have different configurations of windings, or the wire that encircles the toroidal shape of the core. In windings, there will be two wires, one which carries the circumferential current, and one which is the return wire. The return wire can wrap around the core or simply run between the outside of the core and the inside of the winding.

While a small and passive, toroidal inductors are an essential component in electronics. The size, windings, and function of the component will be important to consider in choosing the right inductor.


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