This circuit was found in old American documentation. It is a Wien bridge with the component values calculated by the formulas next to the diagram.
This circuit generates various types of sounds and can be used as a toy. The circuit is from Radio...
The Buck-type DC-DC converter (voltage lowerer) shown in figure 11 is suggested by Analog Devices...
This circuit is from an American technical documentation from the 70s, but it can be easily...