This circuit was found in a 80s American documentation. The zener diodes determine the points of action of each stage and the transistors can be general purpose types.
This circuit appears in several versions in publications of the time and can be modified by...
This configuration with FET and Unijunction can be found elsewhere on this site. The JFET admits...
We found this circuit in a Popular Electronics from the 90s. It operates at a frequency of 15 kHz....