Wow, this is a lot of power 330V*5A = 1.65kW
And the input current (drawn from 12 voltage source) will be larger then 1.65kW/12V = 138A.
So, unfortunately, I cannot help with this. Building such a high power converter is not an easy task.
why not? a 100watts or 1000Watts have the same functions! only the diameter and the core change!
but i only need a formula precisly for the numbers of windins of my etd34!
The EDT34 core is not capable of providing 1650 Watts , @Jony130 mentioned.
This is what I found online about the EDT34 core: ETD34 Switching Power Transformer Electronic Transformer
Ⅰ . ETD34 high frequency transformer size(unit:mm)
Ⅱ . ETD34 high frequency transformer performance
1.working frequency:40kHz-500KHz
2.output power:15 to 60 W
3.operating temperature:-40℃ to +125℃
4.storage temperature:-25℃ to +85℃
5.Store humidity:30 to 95%
The design process is a little "large and bulky" to be described in a forum. I know you just want to know the formula and get on with the design but you need the right formula for your design. For that, you might find the design guides at the URL below to be of help. If nothing else it will help you prepare an explanation of exactly what you need to know to get the job done.
DickCappels thank you for this site! i hope it will help me finding what i want (formula) and if result is suitable! i will take you inform!
have a nice day!