Types of Low-Frequency Transformers and Their Functions

Low-frequency transformers are typically divided into interstage coupling transformers, input transformers, and output transformers, all of which resemble power transformers in shape.

Interstage Coupling Transformer: Used to couple two audio amplifier stages, this transformer allows the output from one stage to pass to the next, ensuring proper impedance matching.

Input Transformer: In early semiconductor radios, the input transformer was used between the audio push and power amplifier stages to couple signals. It can be either single-ended or push-pull, depending on the circuit configuration.

Output Transformer: The output transformer connects the amplifier’s output to the speaker, playing a critical role in signal transmission and impedance matching. They can be either single-ended or push-pull depending on the design.