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1.1 Definition of inductance:
Mioming is the ratio of cross -magnetic flux in the inside of the wire and the surrounding area.
When the DC current is passed through the inductance, only a fixed magnetic force line is present around it, which does not change without time; but when the current is communicated in the coil, the magnetic lines that change over time will appear around. Based on the law of Farage’s electromagnetic induction -magnetic electricity, the change of the changing magnetic lines will generate induction potential at both ends of the coil. This induction potential is equivalent to a “new power supply”. When the closed circuit is formed, the induction potential must generate an inductive current. The total amount of magnetic lines generated by the inductive current from the Lenci Law should try to prevent changes in the original magnetic line. Because the original magnetic line change comes from the changes in external intercourse changes, from the objective effect, the inductor coil has the characteristics of preventing current changes in the AC circuit. The inductor coil has the characteristics of similarity to the inertia in mechanics. It is named “Self -induced” in electrical science. It is usually sparks when the sword switch is turned on or connected to the sword switch. Caused by high induction potential.
In short, when the inductive coil is received on the AC power supply, the magnetic line inside the coil will change with the turnover of the current, causing the coil to continue to produce electromagnetic induction. The electromotive force caused by the changes in the coil itself is called “self -induction”.
In this, the amount of inductance is only a parameter related to the number of coils, size and shape, and medium. It is the amount of inductance coil inertia and has nothing to do with the current.

1.2 The inductance coil and transformer
Mioming coil: When there is current in the wire, the magnetic field is established. Usually we wrap the wires into coils to enhance the magnetic field inside the coil. The inductance coil is made by the wires (lacquer wires, gauze, or naked wires) in a circle (in insulating each other in the wires) by the insulation tube (insulation, iron core, or magnetic core). In general, the inductive coil has only one winding.
The transformer: When changing the current flowing in the inductance coil, not only does the induction voltage at both ends, but also can generate induction voltage in the nearby coil. This phenomenon is called interoperability. Two coils that are not connected to each other but approach each other are generally called transformers.

1.3 The symbol of inductance
induction symbols: L

inductor units: Heng (H), MHheng (MH), Weheng (UH) , 1H = 103mh = 106UH.
The name of the inductance quantity: direct benchmark, color ring standard, non -standard
induction directionality: no direction
Check the inductance measurement method: measure the inductance of the inductor measuring instrument Quantity; measured by a multimeter, the ideal induction resistance is small, which is almost zero.

1.4 Classification of inductance:
Classified by inductance: fixed inductance, variable inductor.
The category according to the nature of the guide magnet: empty core coil, iron oxygen coil, iron core coil, copper core coil.
The classification according to the nature of the working: antenna coil, oscillation coil, choke coil, hoeing coil, and deflection coil.
The classification of winding structure: single -layer coil, multi -layer coil, bee -type coil.
The classification of working frequency: high frequency coil, low frequency coil.
The classification of structural characteristics: magnetic core coils, variable electromotine coils, color code inductor coils, magnetic core coils, etc.

. The role of inductance
Basic effects: filtering, oscillation, delay, trap, etc.
image saying: “DC, blocking flow”
The explanatory explanation theory saying : In the electronic circuit, the inductor coil has a limited role in AC. It can form Qualcomm or low -pass filter, migrant circuit and resonance circuit, etc. with resistors or capacitors; Change, etc.
This from XL = 2πfl, the larger the inductance L, and the higher the frequency F, the greater the sensory resistance. The voltage at both ends of the induction device is proportional to the inductance L, and it is also proportional to the current change speed △ I/△ T. This relationship can also be represented by the following formula:
n , It stores electrical energy in the form of magnetic, and the size of the electric energy stored can be represented by the following formula: WL = 1/2 li2.
It can be seen that the larger the coil inductance, the larger the flow, the more electricity stored.
The most common role of inductors in circuits is to form an LC filter circuit with capacitors. We already know that the capacitance has the ability to “block DC and communicate”, while the inductance has the function of “DC and blocking flow”. If the DC electricity accompanied by many interference signals via LC filter circuit (pictured), then the AC interference signal will consume the capacitor into thermal energy; when the DC current that becomes more pure It becomes magnetic and thermal energy, and the high frequency is the easiest to be impeded by the inductance, which can inhibit the higher frequency interference signal.

LC filter circuit
The inductance part of the power supply part of the line board is generally surrounded by a circular magnetic core with a very thick line diameter. And there are generally several tall filter aluminum electrolytic capacitors nearby. The two are composed of the above LC filter circuit. In addition, the line board also uses a large number of “snake lines patch 钽 capacitors” to form an LC circuit, because the snake line is folded back and forth on the circuit board, which can also be regarded as a small inductance.

. The main characteristic parameters of the inductance
2.1 The amount of inductance L
Melectomatical volume l represents the inherent characteristics of the coil itself, which has nothing to do with the current. Except for the special inductance coil (color code inductance), the amount of inductance is generally not specifically marked on the coil, and it is marked in a specific name.

2.2 Sensing resistance XL
This coils The size of the inductance coil on the AC current hindered XL, the unit is Ohm. The relationship between it and the inductance volume L and AC electro -frequency F is xl = 2πfl

2.3 Quality factors Q
Quality factors Q are a physical quantity of coil quality. The ratio of the resistance, that is,: q = xl/r. The higher the Q value of the coil, the smaller the loss of the circuit. The Q value of the coil is related to the DC resistance of the wire, the medium loss of the skeleton, the loss caused by the shielding cover or the iron core, and the effect of high -frequency skin effect. The Q value of the coil is usually tens to hundreds. Using magnetic core coils, multiple coils can increase the Q value of the coil.

2.4 distributed capacitors
The turns and turns, coils and shielding hoods, coils and bottom versions of the coils are called distributed capacitors. The existence of distributed capacitors reduces the Q value of the coil and becomes poor in stability. Therefore, the smaller the distributed capacitance of the coil, the better. The use of segmented winding method can reduce distributed capacitors.

2.5 Allow error: The actual value of the inductance and the difference between the difference in the nominal value is obtained by the nominal value.

2.6 Name current: refers to the current allowed by the coil to pass, usually represents the letters A, B, C, D, and E, respectively. 1600mA.

. The commonly used inductance coil
3.1 Single -layer coil
The single layer coil is around the paper tube or the gum cuber skeleton with a circle of insulation wires. Such as the crystal radio -waves in the middle wave antenna coil.

3.2 Bee room coil
If the wound coil, the plane does not parallel with the rotation surface, but intersects into a certain angle. This coil is called a bee -type coil. And its rotation for a week, the number of times the wires are bent back and forth, often called the number of folding points. The advantage of the bee -type winding method is that the volume is small, the distributed capacitance is small, and the amount of inductance is large. The bee -type coils use the bee house winding machine to wind. The more folding the point, the smaller the distributed capacitance
3.3 iron oxygen core coils
The size is related to the magnetic core. Inserting the iron oxygen magnetic core in the empty core coil can increase the amount of inductance and increase the quality of the coil.

3.4 Copper core coil
The copper core coils are applied more in the ultra -short wave range. Use the position of the rotating copper core in the coil to change the amount of inductance. This adjustment is more convenient and durable.

3.5 color code inductor coil
is a high -frequency electrostatic coil. It is made of epoxy resin or plastic with epoxy or plastic on the magnetic core. Its operating frequency is 10kHz to 200MHz, and the amount of inductance is generally between 0.1UH and 3300UH. The color code electromotor is an inductor with a fixed inductance. Its unit is UH.

3.6 Streaming circles (choiring circles)
The coils that are limited to AC power are called streaming rings, high -frequency resistance rings and low -frequency stream circles.
3.7 deflection coil
The deflection coil is a load of the output stage of the TV scanning circuit. The deflection coil requires: high deflection sensitivity, uniform magnetic field, high Q value, small volume, and low price.

5. The model, specifications and naming of inductance.
The inductive manufacturers at home and abroad, of which famous brand manufacturers include SAMUNG, PHI, TDK, AVX, Vishay, NEC, Kemet, Rohm, etc.
5.1 chip inductance
induction: 10NH ～ 1mh
Material: iron oxygen wound ceramic layer
accuracy: j = ± 5% k = ± 10% M = ± 20%
Size: 0402 0603 0805 1008 1206 1210 1812 1008 = 2.5mm*2.0mm 1210 = 3.2mm*2.5mm
R n
5.2 Power inductance
Miomay: 1NH ～ 20MH
/RH74/RH104R/RH105R/RH124; CD43/54/73/75/104/105;
Individual schematic diagram: Patch power inductance shielding power inductance
n5.3 piece -like magnetic beads
Type: CBG (ordinary type) impedance: 5Ω ～ 3kΩ
CBH (large current) impedance: 30Ω ～ 120Ω
cby (spikes) impedance: 5Ω ～ 2kΩ
individual schematic diagram: Post Label Magnetic Bead Patch Large -current Magneto

Specifications: 0402/0603/0805/1206/1210/1806 (Patch Magnetic Bead)
Large -current magnetic beads)
5.4 Plug -in magnetic beads

Specifications: RH3.5

5.5 color ring inductance
inductors: 0.1UH ~ 22mh
Size: 0204, 0307, ​​0410, 0512
Bean -shaped inductance: 0.1uh ～ 22mh
Size: 0405, 0606, 0607, 0910
Smooth: J = ± ± 5% k = ± 10% m = ± 20%
Certain accuracy: j = ± 5% k = ± 10% m = ± 20%
The color ring inductor reading of the plugin: the sign of the same color ring resistor

5.6 vertical inductance
induction volume: 0.1UH ～ 3mh
Electronic
Specifications: LGC0410/LGC0513/LGC0616/LGC1019
Direct sense: 0.1UH-10mh.
The rated current: 65mA ~ 10A.
Q value is high, the price is generally low, and the self -resonance frequency is high.

5.8 Magnetic ring inductance
specifications: TC3026/TC3726/TC4426/TC5026
Size (unit MM): 3.25 ~ 15.88
5.9 air Core inductance
The air core inductance In order to obtain a large inductance value, it is often made of more paint bags. In order to reduce the effects of the line resistance of the inductance itself on DC current, it is necessary to use a thick lacquer cable. However, in some small products, the inductance of the heavy air core is not realistic, which not only increases costs, but also limits the volume of the product. To increase the light weight to increase the inductance value, we can insert magnetic heart and iron heart in the air core inductance, improve the self -sense of inductance, thereby increasing the inductance value. At present, most of the computer is magnetic inductance.

6. The common magnetic core magnetic ring
The iron powder core series
The material is: -2 material (red/transparent), -8 material (yellow/red),- 18 materials (green/red), -26 materials (yellow/white),-28 material (gray/green), -33 material (gray/yellow), -38 material (gray/black), -40 material (green//green/ Yellow), -45 Materials (Black), -52 Materials (Green/Blue); Size: outer diameter from 30 to 400d (annotation: outer diameter from 7.8mm to 102mm).
The iron and silicon aluminum series
The main U values ​​are: 60, 75, 90, 125; size: outer diameter from 3.5mm to 77.8mm.

The specifications of the two products, in addition to the main ring shape, are also E -shaped, stick -shaped, etc., and can also be customized according to the various parameters provided by the customer. They are widely used in computer motherboards, computer power supply, power supply, mobile phone charger, lighting transformer light meter, uninterrupted power supply (UPS), various household appliances control boards, etc.

8. Matters that should be paid attention to during use
8.1 The use of inductors
It humidity and dryness, high frequency or low -frequency environment, to allow allowed to allow to allow The inductance is emotional, or the impedance characteristics, etc., you must pay attention.

8.2 The frequency characteristics of the inductance
In at low frequency, the inductance generally presents the inductive characteristics, which only sets up capacity and filter the high frequency characteristics.
but at high frequency, its impedance characteristics are obvious. There is a phenomenon such as energy consumption fever and reduced perceptual effects. The high -frequency characteristics of different inductors are different.
The inductance of the iron oxygen material is explained:
The iron oxygen material is iron magnesium alloy or iron nickel alloy. This material has a high magnetic rate. He can be an inductive coil winding. The capacitance generated in the case of high frequency and high resistance is the smallest. The iron oxygen material is usually used in high frequencies, because at low frequencies, they are mainly inductive characteristics, making the losses on the line very small. Under high frequency, they are mainly electrical resistance ratio and change frequency. In practical applications, the iron oxygen material is used as a high -frequency compliance device for radio frequency circuits. In fact, the iron oxygen is better equivalent to the parallel of resistance and inductance. The low -frequency resistance is short -circuited by the inductance, and the inductance impedance at high frequency becomes quite high, so that the current is all through the resistance. Oxygen is a consumption device, which is transformed into a thermal energy on it, which is determined by his resistance characteristics.

8.3 The maximum current to the inductor design and the corresponding heating situation.

8.4 When using the magnetic ring, find the corresponding L value of the corresponding L, and the corresponding range of the material is found.

8.5 Pay attention to the wires (lacquer cables, gauze or naked wires), commonly used lacquer cables. Find the most suitable line scripture