Inductor coil Inspecting

(1) When selecting and using shielded power inductors or inductors, we must first think of the inspection and measurement of the coil, and then judge the quality and pros and cons of the coil. In order to accurately detect the inductance and quality factor Q of miniature inductor, special instruments are generally needed, and the test method is more complicated. In actual work, this kind of detection is generally not carried out, only the on-off check of the coil and the size of the Q value are judged. [1] You can first use the multimeter resistance to measure the DC resistance of the coil, and then compare it with the original determined resistance value or nominal resistance value, if the measured resistance value is much larger than the original determined resistance value or nominal resistance value, or even the pointer is not moving (resistance value tends to infinity X), you can judge the coil break; If the measured resistance value is very small, it is difficult to determine that it is a serious short circuit or a local short circuit. In these two cases, it can be determined that the coil is bad and cannot be used. If the detected resistance is not much different from the original determined or nominal resistance value, the coil can be judged to be good. In this case, we can judge the quality of the coil, that is, the size of the Q value, according to the following circumstances. When the inductance of the coil is the same, the smaller the DC resistance, the higher the Q value; The larger the diameter of the wire, the larger the Q value. If multi-strand wire winding is used, the more strands of the conductor, the higher the Q value; The smaller the loss of the material used in the coil skeleton (or iron core), the higher its Q value. For example, when the high-silicon silicon steel sheet is used as the iron core, its Q value is higher than that when the ordinary silicon steel sheet is used as the iron core; The smaller the coil distribution capacitance and magnetic leakage, the higher the Q value. For example, the Q value of a honeycomb winding coil is higher than that of a flat winding and higher than that of a disorderly winding. When the coil has no shield and there is no metal component around the installation position, its Q value is higher, and on the contrary, the Q value is lower. The closer the shield or metal component is to the coil, the more serious the Q value decrease; The location of the magnetic core should be properly arranged and reasonable; The antenna coil and the oscillation coil should be perpendicular to each other, which avoids the effect of mutual coupling. 

(2) The coil should be inspected before installation Before use, check whether the structure of the coil is firm, whether the turn is loose and loose, whether the lead contact is loose, whether the magnetic core rotation is flexible, and whether there is a slip button. After these aspects are checked, install. 

(3) If the coil needs to be fine-tuned during use, the fine-tuning method should be considered Some coils need to be fine-tuned during use, and it is inconvenient to depend on changing the number of coils, so the method of fine-tuning should be taken into account when selecting. For example, a single-layer coil can be used to remove the number of trapped coils by the end of the method, that is, in advance around one end of the coil 3 to 4 laps, in the fine tuning, moving its position can change the inductance. Practice has proved that this adjustment method can achieve fine-tuning of ± 2%-3% of the inductance. Coils used in short wave and ultra-short wave circuits are often left half a circle as a fine tuning, and the inductance is changed by removing or turning this half circle to achieve fine tuning. The fine-tuning of the multi-layer segment coil can be achieved by moving the relative distance of one segment, and the number of turns of the movable segment should be 20%-30% of the total number of turns. Practice has proved that the fine-tuning range can reach 10%-15%. The inductance of a coil with a magnetic core can be fine-tuned by adjusting the position of the magnetic core in the coil tube. 

(4) The use of coils should pay attention to maintaining the inductance of the original coil When the coil is in use, do not arbitrarily change the shape of the coil. Size and distance between coils, otherwise it will affect the original inductance of the coil. Especially the higher the frequency, that is, the fewer the number of coils. Therefore, the high-frequency coils and inductors for sale used in television sets are generally sealed and fixed with high-frequency wax or other dielectric materials. In addition, it should be noted that in the maintenance, do not arbitrarily change or adjust the position of the original coil, so as not to cause a mismatch fault. 

(5) The installation of the adjustable coil should be easy to adjust The adjustable coil should be installed in an easily adjustable position of the machine in order to adjust the inductance of the coil to achieve the best working state.