The general public thinks there is one thing called a radio. Sure, they know there are radios that pick up different channels, but other than that, one radio is pretty much like the other.

Early radio receivers worked on a principle called Tuned Radio frequency (TRF), patented in 1916. They weren’t very easy to use, requiring each stage to be tuned to the same frequency (until ...

The carrier frequencies for AM operate from 530 kHz to 1610 kHz. Many superheterodyne AM radios use a demodulation circuit designed for 455 kHz. When the listener tunes in a station, an oscillator ...