We found this circuit in a 1967 Electronic design. However, it can be easily implemented even today as it uses only common diodes.
This is the traditional configuration of na Astable Multivibrator using two NPN ttransistor....
This circuit was adapted from an Italian publication that no longer exists. This is “Onda Quadra”...
This FET stage circuit was obtained from old American documentation but can be applied to any FET....