I think I didn't explain my problem fully.
If I want to build "cheap" pulse generator or Flyback PSU, I don't want to use isolated gate drivers and modules. Otherwise I wouldn't have posted my problem here...
I used lots of DCDC converters for gate drives and modules for PSU. But i want to say it again, they are not cheap!
If I want to use DCDC converters in PSU, I said before, there will be startup problem.
I don't want to use gate transformers because, good gate transformers not easy to find and they have some issues too.