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.
We found this circuit in a 1998 documentation. It generates a musical melody tone obtained from a...
This circuit is from a 1997 publication. In it, the circuit uses a light emitter that points to a...
The circuit presented was obtained in a technical documentation from National Semiconductor. The...