This circuit was found in the August 1993 Electronics Now magazine. It is for telephones used on common old-style analog lines.
Found in an old American publication, this article is suitable for incandescent lamps. SCRs can be of...
A bargraph or mobile bar indicator with 4 LEDs can be implemented by connecting the 4093 NAND...
This is an improved version of the previous circuit also found in the December 1990 Radio...