Found in Popular Electronics from the 90s, this 1.5 A power supply can supply voltages selected by a switch. The splitter resistors determine the output steps.
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...