Inductor coils are devices that operate on the principle of electromagnetic induction. When a current flows through a wire, a certain electromagnetic field is generated around the wire, and the wire of the electromagnetic field itself induces a wire in the electromagnetic field. The effect on the wire itself that generates the electromagnetic field is called “self-inductance”, that is, the changing current generated by the wire itself produces a changing magnetic field, which further affects the current in the wire; the effect on other wires in the electromagnetic field range. It is called "mutual feeling."
The electrical characteristics of the inductor are opposite to those of the capacitor, "passing the low frequency, blocking the high frequency." When the high-frequency signal passes through the inductor, it encounters a large resistance and is difficult to pass. However, the resistance of the low-frequency signal when passing through it is relatively small, that is, the low-frequency signal can pass through it relatively easily. The resistance of the inductor to DC is almost zero.
Resistance, capacitance and inductance, they will have a certain resistance to the flow of electrical signals in the circuit, which is called "impedance". The impedance exhibited by the inductor to the current signal is the self-inductance of the coil. Inductor coils Sometimes we refer to it as "inductance" or "coil", which is indicated by the letter "L". When winding an inductor, the number of turns of the coil is generally referred to as the "number of turns" of the coil.
There are several types of inductive coils commonly used in circuits:
Classified by inductance: fixed inductance, variable inductance.
Classified according to the nature of the magnetizer: air core coil, ferrite coil, iron core coil, copper core coil.
Classified according to the nature of the work: antenna coil, oscillating coil, choke coil, trap coil, deflection yoke.
According to the winding structure classification: single-layer coil, multi-layer coil, honeycomb coil, tight-wound coil, inter-wind coil, tire-wound coil, honeycomb coil, chaotic coil.