Inductors can be made of conductive materials coiled cores, typically such as copper wire, can also be removed or replaced with ferromagnetic materials. The core material, which is higher than the air permeability, can bind the magnetic field more tightly around the inductance element, thus increasing the inductance.
There are many kinds of inductance, most of the outside layer of porcelain glaze coil (enamel coated wire) around the ferrite (ferrite) spool, and some protective inductors put the coil completely in the ferrite. The core of some inductance element can be adjusted. This can change the inductance size. Small inductance can be directly etched on the PCB board, using a method of laying spiral trajectory. Small-value inductors can also be manufactured in integrated circuits using the same process as manufacturing transistors. In these applications, aluminum interconnects are often used as conductive materials. Regardless of the method used, the most applied to the actual constraint is a circuit called "Spin Sub", which uses a capacitor and an active component to exhibit the same characteristics as an inductive element. Inductors used for high frequency isolation often consist of a wire that passes through a magnetic column or bead.