Selection and Testing of Inductors

The selection of inductors should consider factors such as their specific usage, function, circuit requirements, environment, and cost. In high-frequency circuits, silver coated wires should be used to make hollow coils to solve the "skin effect" of high-frequency currents; In order to increase the inductance, materials can be selected as magnetic cores based on the working range of the inductor, such as using nickel zinc ferrite material at high frequencies.

Measuring the DC resistance of an inductor using the "ohm" range of a multimeter can preliminarily detect its quality. If the measured resistance value is less than the standard resistance value of the same inductance, it indicates a short circuit phenomenon inside the coil. The smaller the measured resistance, the more serious the short circuit phenomenon. If the measured resistance is large and shows infinite resistance, it indicates that the internal wire of the coil has been broken.

For coils with multiple windings, a multimeter should be used to check for short circuits and open circuits between each winding. For coils with magnetic cores or metal shields, check for short circuits between their coils and the iron core or metal shield.

In addition, when using inductors, the following issues should be noted.

For adjustable inductance coils with magnetic cores, it is required that the thread of the magnetic core fits well. It should rotate easily without slipping.

The damage of inductors is generally caused by excessive external force or poor use environment, dampness, mold, and corrosion. Once it is found that the coil is broken or has multiple short strands, the welding points or frequently twisted areas at the coil outlet should be checked first. When using an inductive coil, it is important not to arbitrarily change its shape and the distance between the coils, as this will affect the inductance and quality factors of the coil, making it particularly important for high-frequency inductive coils.

During the installation process of multiple coils, the placement of each coil should meet the requirements to minimize interference between them. For example, in a radio receiver, the antenna coil should be kept at a certain distance from the position of the intermediate frequency transformer, and the two types of magnetic cores should be installed perpendicular to each other.