The inductance coil is generally composed of a magnetic core or iron core, a skeleton, a winding group, a shielding cover, and packaging materials.

1. The skeleton generally refers to the stent on which the coil is wound. Some large fixed inductors or adjustable inductors (such as oscillating coils, choke coils, etc.), most of which are enameled wire (or yarn covered wire) directly wound on the skeleton, and then magnetic core or copper core, iron core Wait for the inner cavity of the skeleton to increase its inductance. The skeleton is usually made of plastic, bakelite, ceramic, and can be made into different shapes according to actual needs.

Small inductance coils (such as I-shaped inductors) generally do not use a skeleton, but directly wind the enameled wire on the magnetic core.

Air-core inductance coils (also called out-of-body coils or air-core coils, mostly used in high-frequency circuits) do not use magnetic cores, skeletons and shielding covers, etc., but are wound on the mold before removing the mold, and pulling between the coils Drive a certain distance.

2. Winding refers to a set of coils with prescribed functions, which are the basic components of inductance coils.

There are single-layer and multi-layer windings. There are two types of single-layer windings: close winding (the wires are wound next to each other) and indirect winding (the wires are separated by a certain distance when winding); the multilayer winding has layered flat winding and random winding. Winding, honeycomb winding and many other methods.

3. Magnetic cores and magnetic rods Magnetic cores and magnetic rods generally use nickel-zinc ferrite (NX series) or manganese-zinc ferrite (MX series) and other materials. It has "I" shape, cylindrical shape, cap shape, "E" shape, Various shapes such as pot shape and ring shape.

4. The core material mainly includes silicon steel sheet, permalloy, etc., and its shape is mostly "E" type.

5. In order to prevent the magnetic field generated by some inductive coils from affecting the normal operation of other circuits and components, the shielding cover is added with a metal screen cover (such as the oscillation coil of a semiconductor radio, etc.). The inductor with a shielding case will increase the loss of the coil and reduce the Q value.

6. Packaging materials Some inductors (such as color code inductors, color ring inductors, etc.) are wound, and the coils and magnetic cores are sealed with packaging materials. The packaging material is plastic or epoxy resin.

(2) Small fixed inductance coil

Small fixed inductance coils are usually made of enameled wire directly wound on the magnetic core. They are mainly used in circuits such as filtering, oscillation, trapping, delay, etc. It has two types of packaging, sealed and non-sealed, and both are available. There are two appearance structures, vertical and horizontal.

1. Vertical sealed fixed inductor The vertical sealed fixed inductor adopts the same-directional pin. There are LG and LG2 series inductors made in China. The inductance range is 0.1~2200μH (directly marked on the shell), and the rated working current is 0.05 ~1.6A, the error range is ±5%~±10%. TDK series color code inductors are imported, and the inductance is marked on the surface of the inductor with color dots.

2. Horizontal sealed fixed inductors Horizontal sealed fixed inductors use axial pins, and domestically produced LG1, LGA, LGX and other series.

The inductance range of LG1 series inductors is 0.1~22000μH (directly marked on the shell), the rated working current is 0.05~1.6A, and the error range is ±5%~±10%.

The LGA series inductors adopt an ultra-small structure, and the shape is similar to 1/2W color ring resistors. The inductance range is 0.22~100μH (marked on the shell with the color ring), and the rated current is 0.09~0.4A.

LGX series color code inductors also have a small package structure, with an inductance range of 0.1 ~ 10000μH, and the amount of current is divided into four specifications: 50mA, 150mA, 300mA and 1.6A.

(3) Adjustable inductor

Commonly used adjustable inductors include oscillating coils for semiconductor radios, line oscillating coils for televisions, line linear coils, intermediate frequency trap coils, frequency compensation coils for audio, choke coils, etc.