This circuit was designed to power the previous circuits of the wireless sound system, but it can be used for other purposes. The circuit is from a Radio Electronics from August 1988.
This circuit is a from publication 1980, but still can be mounted with BC548 transistors for Q1...
This circuit for testing zener diodes by lifting their curve on an oscilloscope was presented in...
This high quality circuit with complementary symmetry was found in an Electronics World of 1966....