Other versions exist on this site from various publications. This one is from the Radio Electronics Experimenter from 1990. The bargraph circuit uses the UAA170.
Found in a Popular Electronics from the 90s, it applies to the old answering machines that used...
The operation of this circuit is not common today, but equivalents can be experienced. The circuit is...
This circuit was found in an English publication from 1989. The integrated circuits are of the...