Type of inductor

The original elements that can produce inductance are collectively referred to as inductance originals, fixed inductors, choke coils, television permanent linear coils, line, frame oscillation coils, deflection coils, heads on tape recorders, delay lines, etc., which are commonly used inductive components.

1 fixed inductors: generally use leaded soft magnetic I-core, inductance can be done between 10-22000uh, Q value controlled at 40 or so.

2 choke: He is a coil with a certain inductance, its purpose is to prevent high-frequency current through some frequencies, such as the filter choke ring rectifier circuit, TV choke and so on.

3 rows of linear coils: Used in series with the deflection coil to adjust the linearity of the line. It is composed of I-shaped magnetic core coil and constant magnetic block. The general color TV uses a direct current 1.5A inductance 116-194uh frequency: 2.52MHZ

4-line oscillation coil: It is composed of skeleton, coil, adjusting rod and thread core. The general inductance is 5mh adjustment is greater than +-10mh.

Inductor quality factor and inherent capacitance (1) Inductance and accuracy The size of the coil inductance is mainly determined by the diameter of the coil, the number of turns, and whether the core. The inductance of the inductor is different, and the required inductance is also different. For example, in a high-frequency circuit, the inductance of a coil is generally 0.1uH-100Ho.

The accuracy of the inductance, that is, the error between the actual inductance and the required inductance, depends on the application. Higher requirements for the oscillation coil, o. 2-o. 5%. The requirements for coupled coils and high frequency chokes are low, allowing 10-15%. For some applications where high accuracy of inductance is required, it is generally only possible to test with the instrument after winding, by adjusting the distance between the turns near the edge or the position of the core in the coil.

(2) Quality factor of coil The quality factor Q is used to represent the loss of the coil. The high frequency coil is usually 50-300. The Q value of the tuned loop coil is required to be higher. The resonant circuit composed of the high Q value coil and the capacitor has better resonance characteristics; the resonance circuit composed of the low Q value coil and the capacitor has no obvious resonance characteristics. For coupling coils, the requirements can be lower, and there is no requirement for high-frequency chokes and low-frequency chokes. The size of Q affects the selectivity, efficiency, filtering characteristics, and frequency stability of the loop. Generally, it is desirable to have a large Q value, but it is not easy to increase the Q value of the coil. Therefore, appropriate requirements should be made on the Q value of the coil according to the actual use situation.

The quality factor of the coil is:

Q=ωL/R Where:

ω - working angular frequency;

L - the inductance of the coil;

R - the total loss of the coil. The total loss resistance of the coil, which is composed of the DC resistance, high frequency resistance (caused by the skin effect and proximity effects), and dielectric loss. ""

In order to improve the quality factor Q of the coil, silver-plated copper wire can be used to reduce the high-frequency resistance; multiple strands of insulated wire are used instead of the single-stranded wire with the same president to reduce the skin effect; the use of low dielectric loss Frequency porcelain as the skeleton to reduce dielectric loss. Although using the magnetic core to increase the core loss, but can greatly reduce the number of turns of the coil, thereby reducing the direct current resistance of the wire, to improve the coil Q value.

(3) Intrinsic Capacitance There is a distributed capacitance between the turns of the coil winding, and there are distributed capacitances between layers of the multilayer winding. These distributed capacitors can be equivalent to a capacitor Co in parallel with the coil.