It serves as a reference, since today we can have simpler and more compact solutions. This circuit is from an Electronics Experimenter Handbook from 1992. The integrated circuits are from that time.
Found in 1965 Delco Radio documentation, this circuit uses transistors from that era. Modern...
This circuit was obtained in a 1979 publication but can still be easily assembled today by...
This receiver was found in a documentation by Gernsback from 1960. The circuit uses high impedance...