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, which is present in other points of this website, was found in a 90s Hands On...
Suggested by Siliconix in documentation from the 90's, this circuit supports current equivalent...
This circuit is suitable for applications in medical, research and industrial equipment. The...