The inductor coil is wound on the insulating pipe by the conductor, and the conductor is insulated from each other. The insulating pipe can be hollow, and it can also contain iron core or magnetic powder core, which is called inductance for short. Expressed in L, the units are Henry (H), millihenry (MH), micro Henry (Uh), 1H = 10 ^ 3mh = 10 ^ 6uh.
一、 Classification of inductors
According to the type of inductance: fixed inductance, variable inductance.
According to the nature of the magnet: Air core coil, ferrite coil, iron core coil, copper core coil.
According to the nature of work: antenna coil, oscillation coil, choke coil, notch coil, deflection coil.
According to the winding structure: single layer coil, multilayer coil and honeycomb coil.
二： Main characteristic parameters of inductance coil
1. Inductance L
The inductance L represents the inherent characteristics of the coil, independent of the current. In addition to the special inductance coil (color code inductance), the inductance is generally marked with a specific name instead of the coil.
2. Inductive reactance XL
Inductance coil on the size of the AC current blocking effect called inductive reactance XL, the unit is Ohm. Its relation with inductance L and AC frequency f is XL = 2 π fl
3. Quality factor Q
The quality factor Q is a physical quantity indicating the quality of the coil. Q is the ratio of the inductive reactance XL to its equivalent resistance, i.e., 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 conductor, the dielectric loss of the skeleton, the loss caused by the shield or iron core, and the influence of high frequency skin effect. The Q value of the coil is usually tens to hundreds.
4. Distributed capacitance
The capacitance between turns of coil, between coil and shield, and between coil and substrate is called distributed capacitance. The existence of distributed capacitance makes the Q value of the coil decrease and the stability becomes worse, so the smaller the distributed capacitance, the better.
1. Single layer coil
Single layer coil is a kind of insulation wire which is wound on paper tube or bakelite frame one by one. Such as transistor radio medium wave antenna coil.
2. Honeycomb coil
If the plane of the winding coil is not parallel to the rotating surface, but intersects at a certain angle, this kind of coil is called honeycomb coil. The number of times that the wire bends back and forth in a circle of rotation is often referred to as the number of fold points. The advantages of honeycomb winding method are small volume, small distributed capacitance and large inductance. The honeycomb coil is wound by the honeycomb winding machine. The more the break point, 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 magnetic core. When ferrite core is inserted into the air core coil, the inductance and the quality factor of the coil can be increased.
4. Copper core coil
Copper core coil is widely used in ultrashort wave range. The inductance can be changed by rotating the position of copper core in the coil, which is convenient and durable.
5. Color coded inductor
Color coded inductor is an inductor with fixed inductance. Its inductance is marked by color ring like resistance.
6. Choke (choke)
The coil that restricts alternating current passing through is called choke coil, which is divided into high frequency choke coil and low frequency choke coil.
7. Deflection coil
Deflection coil is the load of output stage of TV scanning circuit. The requirements of deflection coil are: high deflection sensitivity, uniform magnetic field, high Q value, small volume and low price.