Adjustable Inductor

A detailed introduction to the classification and application scope of adjustable inductors:
adjustable inductors include oscillation coils for semiconductor radios, horizontal oscillation coils for televisions, horizontal linear coils, intermediate frequency trap coils, frequency compensation coils for audio, wave blocking coils, etc.
1. Oscillating coils for semiconductor radios This oscillation coil forms a local oscillation circuit with variable capacitors in semiconductor radios, and is used to generate a local oscillation signal that is 465kHz higher than the radio signal received by the input tuning circuit. Its exterior is a metal shielding cover, and its interior is composed of a nylon liner, an I-shaped magnetic core, a magnetic cap, and a pin seat. There is a winding made of high-strength enameled wire on the I-shaped magnetic core. The magnetic cap is installed on the nylon frame in the shielding cover and can be rotated up and down. The inductance of the coil can be changed by changing its distance from the coil. The internal structure of the intermediate frequency trap coil of a television is similar to that of the oscillation coil, except that the magnetic cap has an adjustable magnetic core.
2. Line oscillation coil for television The line oscillation coil is used in early black-and-white televisions. It forms a self-excited oscillation circuit (three-point oscillator or intermittent oscillator, multivibrator) with peripheral resistors and capacitors and line oscillation transistors, etc., to generate a rectangular pulse voltage signal with a frequency of 15625HZ. There is a square hole in the center of the magnetic core of the coil. The line synchronization adjustment knob is directly inserted into the square hole. By rotating the line synchronization adjustment knob, the relative distance between the magnetic core and the coil can be changed, thereby changing the inductance of the coil, so that the line oscillation frequency remains at 15625HZ, and synchronizes with the line synchronization pulse sent by the automatic frequency control circuit (AFC).
3. Line linear coil The line linear coil is a nonlinear magnetic saturation inductor coil (its inductance decreases with the increase of sheep current). It is generally connected in series in the line deflection coil loop, and its magnetic saturation characteristics are used to compensate for the linear distortion of the image.
The line linear coil is made of enameled wire wound on an "I"-shaped ferrite high-frequency magnetic core or ferrite magnetic rod, and an adjustable permanent magnet is installed next to the coil. The purpose of linear compensation is achieved by changing the relative position of the permanent magnet and the coil to change the inductance of the coil.