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 circuit was published in a 1979 magazine, but it can still be easily assembled, as the...
This configuration found in GE documentation from the 90s, can also be seen elsewhere in this...
This simple circuit has good gain and can be implemented with any general-purpose transistor. The...