In radio communications, broadcast television, and automatic control, it is used as a component of voltage amplification, power output and other circuits.
The audio transformer has a uniform frequency response in the working frequency band, and its core is made of high-permeability materials. The primary and secondary windings are tightly coupled, so that almost all the magnetic flux passing through the primary winding is linked with the secondary winding, and the coupling coefficient is close to 1.
The low frequency of the passband is determined by the inductance of the primary winding, and the high frequency is determined by the leakage inductance of the transformer. To ensure that the transformer has enough pass band, the original winding inductance should be large, and the leakage inductance should be small. The hysteresis loss of the iron core and the saturation of the magnetic circuit will cause signal distortion. Properly configure the load and increase the load current to reduce the effect of hysteresis loss; increase the core section and leave an air gap to prevent the magnetic circuit from being saturated, which can reduce signal distortion.