This circuit with unijunction transistors was found in a documentation from the 80's. The trigger times of the SCRs depend on the capacitors and are adjusted in the 5M (4M7) potentiometers.
This low power circuit can be powered with voltages from 1.8 V. We find it in a 80s Hands On...
This simple unijunction and bipolar generator appeared in Radio Electronics magazine in September 1865....
This circuit was obtained from an old American documentation having a limited adjustment range....