We found this circuit in an old American publication from the 1980s. Transistors can be general-purpose types like the BC548, and the tuning frequency is given by the L and C components.
This circuit was obtained in a 1975 documentation. The maximum frequency depends on the diodes and the...
Found in a 1990 Hobbyst Handbook this circuit has an output power of a few tens of watts and...
The circuit shown is a constant current source which allows the reading of resistors on a very low...