Employing the XR2206 IC, this circuit was found in the May 1977 issue of Radio Electronics magazine. The formula next to the diagram gives the component values as a function of frequency.
Any general purpose PNP transistor such as the BC558 can be used on this circuit from an old...
This circuit is from a 1965 General Electric hobby manual. The circuit can be assembled with...
This circuit was found in a Maxim documentation from the 90s. It is valid for the lower income types...