: Can you send me a shemas please because Im not very good in english and I not very good in electronics.
: Send me a shemas please: firstname.lastname@example.org
This isn't one of my own schematics, I just made a quick search for you, so I can't guarantee the performance of this converter. Actually I can tell you that the output voltage will depend on the load, as there is no output voltage regulation what so ever in this design. You should add a (5A?) fuse on the input line as there isn't any short circuit protection besides the limitation of Hfe in the power transistors. The output frequency of this converter isn't very stable either, but it is a simple square-wave design that I think might suite you.
If you like a lower/higher output voltage, (you use 230V in france don't you?) then you can simply use another transformer. If you exceed the current rating of the transformer you use, it might saturate and damage the output transistors.
PLEASE BE CAREFUL AS THIS DESIGN WILL OUTPUT HIGH VOLTAGES!!