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.
Many designs that use transistors and integrated circuits are powered by a 6V voltage, normally...
This circuit was found in the August 1993 Electronics Now magazine. It is for telephones used on...
The difference of this 1982 circuit is the fact that it uses the input signal itself to obtain the...