Written in an article in Radio Electronics magazine in April 1987, this circuit triggers an alarm via a relay. Details of the sensor are given in the article.
This circuit, from an 80's publication, detects the SCA (Announcer Eliminator) signal from FM...
Found in the July 1980 Radio Electronics magazine, this circuit uses an integrated circuit from...
This low frequency signal converter was found in the July 1983 issue of Radio Electronics...