eli5: On old radios, how does turning the dial tune into a different station? what is happening inside the radio to achieve this?

Question

eli5: On old radios, how does turning the dial tune into a different station? what is happening inside the radio to achieve this?

In: 70

Answer 1

The dial was a variable capacitor, with metal plates that would sweep to mesh across an insulator. A coil wound around a ferrite rod was connected in parallel. Together, these made a “tuned circuit” which resonates at the desired frequency and selects the station. This circuit is “tuned” the same way the space inside a violin emphasizes certain tones.