Dispelling the mysteries of radio. A new series featuring a variety of practical circuits for the set builder and experimenter. This month: Simple Receivers and a Headphone Amplifier.

Towards the end of the 19th century, sending a radio signal a few hundred yards was considered a major achievement. At the close of the 20th, man was communicating with space probes at the outermost edge of the solar system.

No other area of science and technology has affected the lives of people more completely. And because it is so commonplace and affordable, it is accepted without a second thought. The millions of people who enjoy it, use it, even those whose lives depend upon it, often have little more than a vague notion of how it works.

This series of articles will view the technology in a historical perspective and try to dispel its mysteries. The main purpose, however, is to present a variety of practical circuits for set builders and experimenters. And, with economy in mind, basic components and assemblies are repeated in different receivers.