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What is an inductor? What is the inductance coil?

The inductor coil is wound around the insulating tube by a loop of the wire, and the wires are insulated from each other, and the insulating tube may be hollow or may include a core or a magnetic powder core, referred to as an inductor. Expressed by L, the unit is Henry (H), milli-henry (mH), micro-Henry (uH), 1H = 10^3mH = 10^6uH.

First, the classification of inductance
Classified by inductance: fixed inductance, variable inductance.
Classified according to the properties 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.
Classified by winding structure: single layer coil, multilayer coil, honeycomb coil.

Second, the main characteristic parameters of the inductor
1, inductance L
The inductance L represents the inherent characteristics of the coil itself, regardless of the current magnitude. In addition to the special inductor (color code inductor), the inductance is generally not marked on the coil, but marked with a specific name.
2, the anti-XL
The size of the inductive coil that blocks the AC current is called XL, and the unit is ohm. Its relationship with inductance L and AC frequency f is XL=2πfL
3. Quality factor Q
The quality factor Q is a physical quantity indicating the quality of the coil, and Q is the ratio of the inductive reactance XL to its equivalent resistance, that is, Q = XL / R. The higher the Q value of the coil, the smaller the loss of the loop. The Q value of the coil is related to the DC resistance of the wire, the dielectric loss of the skeleton, the loss caused by the shield or the iron core, and the influence of the high frequency skin effect. The Q value of the coil is usually from several tens to several hundreds.
4, distributed capacitance
The capacitance between the turns and turns of the coil, between the coil and the shield, and between the coil and the master is called a distributed capacitance. The presence of the distributed capacitance reduces the Q value of the coil and the stability is deteriorated, so the smaller the distributed capacitance of the coil, the better.

Third, the common coil
1, single layer coil
The single-layer coil is wound around the paper tube or bakelite skeleton in a circle with insulated wires. Such as a transistor radio wave antenna coil.
2, honeycomb coil
If the coil is wound, its plane is not parallel to the plane of rotation, but intersects at an angle. This type of coil is called a honeycomb coil. And the number of times the wire is bent back and forth, often referred to as the number of vertices. The advantage of the honeycomb type winding method is that the volume is small, the distributed capacitance is small, and the inductance is large. The honeycomb coils are wound by the honeycomb winding machine. The more the folding points, the smaller the distributed capacitance.
3, ferrite core and iron powder core coil
The inductance of the coil is related to the presence or absence of a magnetic core. Inserting a ferrite core into the air core coil increases the inductance and improves the quality of the coil.
4, copper core coil
Copper core coils are used in the ultrashort wave range. The position of the copper core in the coil is used to change the inductance. This adjustment is convenient and durable.
5, color code inductor
A color code inductor is an inductor with a fixed inductance, and its inductance sign method is marked with a color ring like a resistor.
6, choke (choke)
The coil that restricts the passage of alternating current is called a choke, and is divided into a high frequency choke coil and a low frequency choke coil.
7, deflection coil
The deflection yoke is the load of the output stage of the television scanning circuit. The deflection yoke requires: high deflection sensitivity, uniform magnetic field, high Q value, small size and low price.

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