What are the coils?
Coils are a passive, two-terminal element capable of generating a magnetic flux when an electrical current is circulated.

The coils are made up of an enamelled copper wire or wire wound in a core, these cores can have different composition either in the air or in a ferrous material such as magnetic steel to intensify their magnetism capacity.

Its unit of measurement is Henry (H) in the International System, but submultiples mH and mH are usually used. To calculate the henries of a coil, the following factors must be considered.

The number of turns or turns you have.
The diameter of the turns
Thread length
The core type
All these factors, the larger or larger the inductance of the coil increases, causing it to have more henries (H).

There are mainly 2 types of coils:
Fixed coils
As its name indicates this type of coil its value is fixed and within this group, we can find coils with an air core and solid core

Air core
The conductor is wound on hollow support and later it is removed, leaving it with an appearance similar to that of a spring. This type of coils have low incubation and are used for high-frequency signals such as radio, TV, transmitter circuits.

air core

Solid core
Within this group, we can find different types of nuclei, be it iron and ferrite

Iron core
When a high inductance value is required, an iron core is used since this creates a greater magnetic effect than when we have the air core.
This core is manufactured in the form of sheets generally in the shape of “E” and “I” in order to avoid energy losses in the induction process.
These coils are mainly used as filters in power sources or in fluorescent lamps where they are called “ballasts”.

iron core

Ferrite core
The ferrite core is currently being used a lot in electronics since it can be used to make high inductance coils and small size, as well as coils for working in high-frequency circuits.
Ferrite is a compound formed with iron oxide powder mixed with other components and coated with an insulating material, which agglutinates and compresses into a solid form.

Ferrite cores are made in rod, “E”, two “Es” stockings, or toroid.
Ferrite core coils are used in various applications as radio antenna coils, such as shocks or high-frequency filters on tuned circuits or power sources.

ferrite core

Toroidal coils
Toroidal coils have a special geometric shape for their core made of ferrite and due to that shape, they are highly efficient.
They are currently used very frequently in filter circuits and in all types of transformers.


Variable coils
Variable inductances are required for certain special applications and are provided with a system by which their main characteristics such as the number of turns or turns, or the position of the core can be changed.