This circuit was found in an American documentation from the 90's. It switches a continuous voltage obtaining an AC voltage at the output of approximately 1 kHz.
Flybacks are no longer misused. However, if the reader wants to recover an old analog television...
Circuits similar to this can be found in this section. This is from 1967 General Electric...
This circuit is from Motorola's 1990 Linear Databook. We can implement it with other operational...