This circuit with a bargraph scale was found in a 90s Popular Electronics. The circuit measures the intensity of a sound in three scales. R14 works as a sensitivity adjustment.
This circuit is from a 1968 documentation using one of the first integrated circuits available at the...
This circuit was found in a 1965 General Electric documentation. SCRs and unijunction may be...
This precision circuit can be implemented with other operational ones. We found it in a...