Found in an Elektor from the 90s, this circuit converts signals from the 280 kHz band to 516 kHz, making it possible to tune them in common AM radios. The components used are from that time.
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...