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.
The configuration presented below was obtained in the Linear Application Handbook of the National...
This circuit was found in December 1983 Radio Electronics magazine. The maximum output current is 1 A...
This untuned circuit uses one of the world's first commercial transistors, the CK722, having been...