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.
This simple version of a function generator with the XR2206 was found in the May 1977 issue of...
In a modern version this circuit can use an LED in series with a resistor in place of the lamp. The...
This VFO was found in a 1980s documentation. The central frequency is given by the crystal and the...