This circuit was found in an American documentation from the 90's. The transistor is a general purpose one. The circuit oscillates well between 12 and 30 MHz with the indicated components.
The circuit in the figure can be used to trigger a triac or even a comparator in a project that...
Suggested by a 90s Electronic Design, this circuit drains only 0.25 mA from its source. Listening...
Found in a 1960 Sylvania manual, this circuit can be implemented with a modern equivalent...