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Basic knowledge of circuit and components:
Inductive components generally apply the principle of electromagnetic induction work of the components collectively referred to as inductive components.Inductance elements, like resistors and capacitors, are the most commonly used important components in electronic circuits.Common inductors are fixed inductors used in general circuits, high frequency choke coils, low frequency choke coils, various inductor coils used in radios and recorders, deflection coils used in television sets, oscillating coils and linear adjustment coils, etc.Although they are not the same in the circuit, but are the use of electromagnetic induction principle to work.Inductance element is generally made of wire (mostly enameled wire or other insulated surface wire) wound into hollow coil or coil with iron core (magnetic core), so it is usually called inductance coil.
Magnetic ring inductance against interference
[Ring inductance] Ferrite beads can be used in circuits to increase high frequency losses without introducing dc losses
And small size, easy to install on the interval of lead or wire, noise signal suppression effect is very obvious, so it can be used for high-frequency circuit decoupling, filtering and parasitic oscillation suppression.
http://www.transformerinductor.com/