It is used in almost all electronic products, and its principle is simple, but the winding process of the transformer will have different requirements according to different use occasions (different uses). The main functions of the transformer are: voltage conversion; Impedance transformation; Isolate; Voltage regulation (magnetic saturation transformer), etc., the commonly used core shape of the transformer is generally E and C core.

the most basic type of a power transformer consists of two sets of coils wrapped with wires and connected to each other in an inductive manner. when an ac current (with a given frequency) flows through one group of coils, an ac voltage of the same frequency will be induced in the other group of coils, and the magnitude of the induced voltage depends on the degree of coupling and magnetic linkage between the two coils.

generally, the coil connected to the ac power supply is called the primary coil; the voltage across this coil is called the primary voltage. the induced voltage in the secondary coil may be greater or less than the primary voltage, depending on the ratio of turns between the primary coil and the secondary coil. therefore, the power transformer is divided into two kinds of boost transformer and buck transformer. most power transformers have a fixed core, which is wound with primary and secondary coils. due to the high permeability of iron, most of the magnetic flux is confined to the core, so the two sets of coils can thus achieve a fairly high degree of magnetic coupling. in some transformers, the coil and the core are so tightly combined that the ratio of the primary to secondary voltage is almost the same as the ratio of the turns of the coil. therefore, the turn ratio of the transformer can generally be used as a reference index for transformer boost or buck. because of this boost and buck function, the transformer has become one of the important appendages of the modern power system, increasing the transmission voltage makes the long-distance transmission of power more economical, as for the buck transformer, it makes the use of power more diversified, we can say that without transformers, the industry could not achieve the current development.

in addition to the small size of the power transformer, there is no clear dividing line between the power transformer and the electronic transformer. the power supply that normally provides a 60hz power network is very large, it may cover half the continental area as large as the capacity. the power limitations of electronic devices are usually limited by the ability of rectification, amplification, and other components of the system, some of which are amplifiers, but which are still in the range of small power when compared to the generating capacity of the power system.

transformers are commonly used in various electronic equipment, the reason is: to provide a variety of voltage levels to ensure the normal operation of the system; provide electrical isolation of the parts of the system operating at different potentials; provides high impedance to ac current, but low impedance to dc; maintain or modify the waveform and frequency response at different potentials.