We found this circuit in the 1992 special edition of the Electronics Experimenter Handbook. The components used are still current, many admitting equivalents.
This circuit provides both frequency and voltage division. The circuit was found in a 1966...
This circuit visually indicates that a high voltage is present in an outlet or other point. The...
Used with infrared remotes at the time, this circuit was found in a 1991 RE Experimenter Handbook....