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.
This two-transistor constant current source is from a 1968 documentation. Modern equivalent...
This converter or inverter uses components that are still common. The transformer is the type...
Using a V/F converter this circuit was found in the June 1991 issue of Radio Electronics magazine. The...