Broadcast band frequency modulation (FM) radio was invented to solve existing problems with noise and fidelity on the amplitude modulation (AM) broadcast band.  Thus, the first FM receivers were quite complex in design, employing a superheterodyne converter, a wideband IF, a limiter stage, and a discriminator.  Unlike the first AM radio sets, the earliest FM radio sets did not use the simplest possible methods for receiving signals.  Perhaps Armstrong, the inventor of most modern radio methods, was fully aware of all the ways to receive FM.  (Someone reading these comments might want to offer the technical history so I can add it here.)  But, it was not until much after the introduction of commercial broadcast FM that simple FM receiver designs were published or sold.

Although the title alludes to simplicity, these radio designs are not uniformly simple. These designs generally have low component counts, however the design or construction my have been far from simple. Read more