1. The inductor is referred to as inductance, which is one of the commonly used basic electronic components.
There are a wide variety of inductors, the shapes are different, more common: single-layer flat air core inductive coil, interwindered wire coil, multi-layer emotional coil, hive-type inductance coil, tape magnetic core Inductor coil, magnetic tank inductive coil, high frequency blocking ring, low frequency blocking ring, fixed inductor, etc.
2. The text symbol of the inductor is "L", and the graphic symbol is shown in Figure 2.
3, fixed inductor (Fig. 3) is a versatile series product, coil (often containing magnetic core) is sealed in the housing, has a small size, light weight, strong structure, and convenient installation. Features.
4. The main parameters of the inductor are inductance and rated current.
The basic unit of inductance is Henry, referred to as Heng, expressed by the letter "H". In practical applications, millimensions or micro-micro (μH) units are generally used. The interrelation between them is: 1 h = 1000 mH, 1 MH = 1000μH. There are two ways to indicate the amount of inductance. One is a straight standard, that is, the inductance is directly printed on the inductor, as shown in Figure 4.
5. The other is the color standard, that is, the use color ring represents an inductance, and its unit is μH.
The first, 2nd ring represents two valid numbers, and the third ring represents a multiplication, and the fourth ring represents the allowable deviation (Fig. 5). The meaning of colors of the colors of the colors is the same as the color charators, and you can refer to the article. The rated current means the maximum current allowed by the inductor during normal operation. In use, the actual operating current of the inductor must be less than the rated current, otherwise the inductor coil will severely heat and even burn.
6, inductor is working with self-inductance.
The inductive coil generates self-inductive moment when the current is passed, the size of the self-sensing force is proportional to the change rate of the current of the inductor coil, and is always opposed to the change in the original current (Fig. 6). Therefore, the inductor has a function of direct flow and blocking flow.
7. The inductor is called the resistance of the resistance presented by the alternating current, indicating the symbol "XL", and the unit is Ω.
The induction is equal to the ratio of the AC voltage (effective value) between the inductor and the alternating current (effective value) through the inductor. The induction resistance XL is proportional to the frequency of alternating current F and the inductor of the inductor (Fig. 7), ie XL = 2 лfl (ω).
8. There are many inductors.
Figure 8 shows an inductor for rectifying power supply filter, L and C1, and C1 constitute π-type LC filters. Since L has a function of flowing a flow resistance, the DC component in the pulsating DC UI of the rectifier output can pass L, and most of the alternating component cannot pass by L, by bypass by C1, C2, the output terminal U0 is Pure DC is.
9, inductor can be used to distinguish high, low frequency signals.
Fig. 9 shows an application example of a high-frequency resistance circle in a reciprocating radio, since the high frequency blocking ring L is large, the high frequency current is very small, the high frequency signal output is output by the transistor Vt collector You can only pass C. After the audio signal after the detection is enlarged by VT, it can be reached through the headset.
10, inductor can be used for resonant selection circuit.
Figure 10 shows the radio high grade circuit, the variable inductor L and C1 constitute a tuning circuit, and the adjustment L can change the resonant frequency, and the role of the set table.
11. The quality of the inductor can be detected with a multimeter (Figure 11).
Put the multimeter in "R × 1" gear, two table pen (not positive, negative) contact with the two-pin foot of the inductor, the gauge indication should be close to "0Ω", the inductor larger inductor should have a certain amount Resist value. If the clinic is not movable, the inner disconnection of the inductor; if the table needle indicates unstable, the internal contact is poor.
12. Transformers are also a common components, which have a wide variety, and the size of the size is very different.
More commonly used in radio and electronic production: power transformers, audio input transformers, output transformers, intermediate frequency transformers, high-frequency transformers, pulse transformers, etc. (Fig. 12).
13, the text symbol of the transformer is "T", and the graphic symbol is shown in Figure 13.
14. Transformers are used to use mutual inductance principles, have the effect of biochemical separation DC, voltage conversion, impedance transformation, and phase transformation.
The transformer is composed of a coil that is uncommon with each other, and there is a core or magnetic core as a coupling medium (Fig. 14). Change the number ratio between the initial and secondary levels, the voltage ratio and impedance ratio can be changed. Changing the method of picking the transformer coil can facilitate down the signal.
15. The power transformer is the most common type of transformer. The main parameters of the power transformer are power and secondary voltage, current.
The square of the power and the core section is proportional, as shown in Fig. 15 (a), the larger the iron core cross section, the greater the transformer power. The purpose of the power transformer is the power supply voltage conversion, and can provide a variety of power supply voltages to accommodate the needs of the electronic circuit, as shown in Fig. 15 (b). When making it, the transformer having a secondary voltage that meets the requirements should be selected as needed.
16. Another purpose of the power transformer is the power supply.
Due to the isolation of the transformer, even if the human body contacts the voltage U2, it will not form a loop with the exchange 220V city electricity to ensure personal safety (Figure 16). This is the truth of the power isolation transformer must be used when repairing hot base appliances.
17. The audio transformer operates in the audio range, with signal voltage transmission, allocation, and impedance matching.
Figure 17 shows the push-pull power amplifier circuit, the input transformer transmits signal voltage, allocated to the transistors VT1 and VT2 (the signal given to VT2), allowing VT1 and VT2 alternately, negative half-week signals, and then again Signal synthesis is output by the output transformer. The output transformer also converts the 8Ω low resistance of the speaker to hundreds of Ou Mi's high resistance, matches the output impedance of the amplifier, so that the audio power output by the amplifier is the largest and the distortion is the smallest.
18. The intermediate frequency transformer is abbreviated as a medium-stricken, and is applied to an intermediate frequency amplitude amplitude circuit of a super-unhevarial radio and a TV. The intermediate frequency transformer has the effect of selective frequency and coupling.
Fig. 18 (a) shows a portion circuit in a super-extraction radio, the primary coils of the intermediate frequency transformers T1, T2 are respectively C1, C2, respectively, respectively, as VT1, VT2 load, therefore, only 465 kHz intermediate frequency signal is enlarged, It played the role of SEV. Fig. 18 (b) is an intermediate frequency transformer thread frequency characteristic curve, and F0 is a resonant frequency, and ΔF is a passband.
19. High-frequency transformers typically refer to transformers working in the radio frequency range.
The magnetic antenna of the radio is a high-frequency transformer, and the primary coil is formed into a selective frequency circuit, and the selected radio signal is transmitted to the high amplifier or variable frequency-converted VT1 (Fig. 19).
20, the transformer can be detected by a multimeter (Figure 20).
First, the detecting winding coil is turned off, and the other is to detect the insulation resistance between the windings coil, and the third is the insulation resistance between the winding coil and the core.
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