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 is a driver for R-2R network of AD converters. We found it in manufacturer...
This circuit was found in an American publication from the 60's. The transistor is made of...
This circuit produces an audio tone on the speaker or magnetic capsule. Rx must be such that added...