We found this circuit with duty cycle adjustment in the May 1988 Radio Electronics magazine. The source must be symmetrical, and the frequency given by R3 and C1.
This circuit is from a 1976 documentation. The diodes can be 1N34 or equivalent, and the power...
This circuit is from a high voltage tube source. It does not include the filament voltage that must...
This circuit is from the Motorola Linear Databook of 1990 and can be implemented with other...