This power source was found in a 1969’ Electronics World. The version is too sophisticated by the current it supplies and can be implemented with modern transistors.
Found in a magazine 73 for radio amateurs, this circuit has two settings, one for the interval and the...
This good quality amplifier found in a 1982 documentation has a traditional complementary output...
A low frequency divider can be made using common unijunction transistors as shown by the figure...