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.
The circuit presented uses Linear Technology Operationals, having been found in a 1993 manual. The...
The amplitude of the output signal of this amplifier is proportional to the hub of the input...
Using the 709 integrated circuit, one of the first operational, this circuit was found in the...