This primitive solar radio was found in a Gernsback publication from 1960. The transistor is made of germanium of the time and the earphone is magnetic with high impedance.
This biestable circuit was found in a Popular Electronics from the 90s. The circuit has an unusual...
This 3-step circuit for generating digital signals was found in the November 1976 issue of Radio...
This circuit for low frequency signals from the Loran guidance system was discovered in the July...