Inductors Inductors used to provide the device, with various insulated wire wound coil called inductance. Its main role is to prevent the exchange of DC, high frequency pass through the low frequency, that is, high-frequency signals through the inductor coil will encounter great resistance, it is difficult to pass, while the low-frequency signal through the resistance presented by the comparison Small, low-frequency signals can pass through it easily. Inductance coil DC resistance is almost zero.

Inductor classification
1, according to the nature of guided magnet Category: air-core coil, ferrite coil, core coil, copper core coil.
2, according to the nature of the work Category: antenna coil, oscillation coil, choke coil, trap coil, deflection.
3, according to the winding structure Category: single-layer coil, multilayer coil, honeycomb coil. High-frequency ceramic chip inductors
4, according to the inductive form of classification: fixed inductance coil, variable inductance coil.
5, according to the structural characteristics of classification: core coil, variable inductance coil, color code inductance coil, no core coil.
In addition, often based on the operating frequency and over current size, divided into high-frequency inductors, power inductors.

The basic use of inductors
1, the role of the inductor is mainly through DC, resistance AC, the main circuit in the filter, oscillation, delay, notch and so on. Inductance coil impede the exchange of current, the size of the impeding effect of resistance XL, the unit is ohm. It and the inductance L and AC frequency f for XL = 2πfL, the inductor can be divided into high-frequency blocking coil and low-frequency blocking coil. Tuning and frequency selection role: inductance coil and capacitor can be composed of LC tuning circuit in parallel. That is, the natural frequency f0 of the circuit is equal to the frequency f of the non-alternating signal, then the inductive reactance and the capacitive reactance of the loop are equal, so that the electromagnetic energy oscillates back and forth between the inductance and the capacitance, and the resonance phenomenon of the LC loop. Resonance and capacitive reactance of the circuit in the resonant state are reversed, the inductance of the total current of the loop is the smallest, and the amount of current is the largest (f = "f0" AC signal). The LC resonant circuit has the function of selecting the frequency, A frequency f AC signal is selected.
2, the inductor also filter signal, filter noise, stabilize the current and inhibit electromagnetic interference and so on. In the electronic equipment, often see some of the magnetic ring, the magnetic ring and the connecting cable form an inductor (wire in the wire around the magnetic ring around the coil inductance), which is commonly used in electronic circuits anti-jamming components , High-frequency noise has a good shielding effect, it is called the absorption of magnetic ring, usually made of ferrite material, also known as ferrite ring (referred to as the magnetic ring). The magnetic ring has different impedances at different frequencies. The impedance is low at low frequencies, and the impedance of the magnetic ring increases dramatically as the signal frequency increases.