This 4-tube counter was found in Radio Electronics magazine from December 1959. The circuit uses a coil as a sensor to detect the passage of metallic parts or magnets.
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...