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.
Found in a 90s 73 magazine, this circuit uses an unusual component today which is the XR2206. |...
An audio amplifier of good power, and great sensitivity; a simple tuning step and a detecting...
This automotive circuit was found in the June 1997 issue of Electronis now magazine. The circuit uses...