The inductor can be made of a coiled core of electrically conductive material, typically a copper wire, or the core can be removed or replaced with a ferromagnetic material. A core material having a higher magnetic permeability than air can tightly constrain the magnetic field around the inductance element, thereby increasing the inductance. There are many types of inductors, most of which are made of an outer enamel coated wire around a ferrite bobbin, and some protective inductors place the coil completely inside the ferrite. The core of some inductive components can be adjusted. This can change the size of the inductor. Small inductors can be etched directly onto the PCB, using a method of laying spiral traces. Small value inductors can also be fabricated in integrated circuits using the same process of fabricating transistors. In these applications, aluminum interconnects are often used as conductive materials. Regardless of the method used, the most practical application of constraints is a circuit called a "rotator" that uses a capacitor and active components to exhibit the same characteristics as an inductive component. Inductive components for high frequency isolation often consist of a wire that passes through a magnetic column or magnetic bead.
Small inductor
Small fixed inductors are usually wound directly on the core with an enameled wire.
Mainly used in circuits such as filtering, oscillation, notching, delay, etc. It is available in both sealed and unsealed packages. Both forms have both vertical and horizontal profiles.
1. Vertical sealed fixed inductor The vertical sealed fixed inductor adopts the same-direction pin. The domestic inductance range is 0.1~2200μH (straight mark on the outer casing), the rated working current is 0.05~1.6A, and the error range is ± 5%~±10%, the inductance of the imported, the current range is larger, and the error is smaller. Imported TDK series color code inductors, the inductance of which is marked on the surface of the inductor with color points.
2, horizontal sealed fixed inductor Horizontal sealed fixed inductor with axial type pins, domestically produced LG1.LGA, LGX and other series.
Inductance of LG1 series inductors ranges from 0.1 to 22000μH (straight on the housing)
The LGA series inductors are ultra-small and similar in appearance to 1/2W color ring resistors. The inductance ranges from 0.22 to 100μH (marked on the housing with a color ring) and the rated current is 0.09~0.4A.
LGX series color code inductors are also small package structures with inductance ranging from 0.1 to 10000μH and rated currents of 50mA, 150mA, 300mA and 1.6A.
Adjustable inductor
Commonly used adjustable inductors include an oscillating coil for a semiconductor radio and a line oscillating coil for a television set.
Linear coils, intermediate frequency trap coils, acoustic frequency compensation coils, wave blocking coils, etc.
1. Oscillation coil for semiconductor radio: This oscillation coil is composed of a local oscillator circuit in a semiconductor radio and a variable capacitor to generate a local signal of 465 kHz higher than the radio signal received by the input tuning circuit. The outside is a metal shield, and the inside is composed of a nylon lining, an I-shaped core, a magnetic cap and a lead seat. The winding of the high-strength enameled wire is used on the I-shaped core. The magnetic cap is mounted on a nylon frame in the shield, and can be rotated up and down to change the inductance of the coil by changing its distance from the coil. The internal structure of the TV IF notch coil is similar to that of the oscillating coil, except that the magnetic cap has a tunable core.
2. The oscillating coil for TV: The oscillating coil is used in the early black-and-white TV. It consists of a self-excited oscillating circuit with a peripheral RC and a oscillating transistor (three-point oscillator or intermittent oscillator, multi-resonant ,) used to generate a rectangular pulse voltage signal with a frequency of 15625HZ.
The center of the core of the coil has a square hole, and the line synchronization adjustment knob is directly inserted into the square hole, and the synchronous adjustment knob is rotated to change the relative distance between the core and the coil, thereby changing the inductance of the coil and maintaining the oscillation frequency of the line. For the 15625HZ, the line sync pulse sent by the automatic frequency control circuit (AFC) generates synchronous oscillation.
3. Linear coil: The linear coil is a nonlinear magnetic saturation inductor (the inductance decreases with the increase of current). It is generally connected in series in the line deflection coil loop and compensated by its magnetic saturation characteristics. Linear distortion of the image.
The linear coil is wound on the "work" type ferrite high-frequency core or ferrite rod with an enameled wire, and an adjustable permanent magnet is arranged beside the coil. The linear inductance is achieved by changing the relative position of the permanent magnet and the coil to change the inductance of the coil.
Blocking inductor
A choke inductor is an inductive coil used in a circuit to block an AC current path.
It is divided into a high frequency choke coil and a low frequency choke coil.
1. High-frequency choke coil: The high-frequency choke coil is also called high-frequency choke coil, which is used to prevent high-frequency AC current from passing.
The high-frequency choke coil works in the high-frequency circuit, and the hollow core or ferrite high-frequency core is mostly used. The skeleton is made of ceramic material or plastic, and the coil is wound by a honeycomb type or a multi-layer flat winding.
2, low-frequency choke coil: low-frequency choke coil is also called low-frequency choke coil, it is applied to current circuit, audio circuit or field output circuit, its role is to prevent low-frequency AC current through.
Generally, the low frequency choke coil used in the audio circuit is called an audio choke, and the low frequency choke coil used in the field output circuit is called a field choke, and the low frequency choke coil used in the current filter circuit. It is called a filter choke.
The low-frequency choke coil generally adopts an "E"-shaped silicon steel sheet core (commonly known as a silicon steel sheet core), a permalloy core or a ferrite core. In order to prevent magnetic saturation caused by large DC current, proper clearance should be left in the core during installation.
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