Here is the circuit I found on net **broken link removed**
I want to ask, based on which things that we know the number of winds of the pulse transformer, the frequency that the output works on and the power of load ?
Hope you hint me some, thanks so much !!!
I recommend you to check the data sheet and application notes available for the control IC 3842. The reason that I did not spell UC3842 is there are many manufacturers who make these. Search for example MC3842.
This is very popular current mode controller, and there should be many application examples.
WARNING: This circuit involves high voltage. You should be very careful.
S. H.
smiles a few things about SMPS,
1- make sure always you have galvanic isolation from mains.
2- always use proper fuse
3- read as much as you can before starting you can find many good books in download section about SMPS
4- again be careful even SMPSes from big and reknown companies sometimes known that can be dangerous. I think it was DELL company some years ago that its computers spontaneously caught fire. so be careful.
Number of winds of your transformer both depends on frequency and material used as core of your transformer. You can find estimates in many books about SMPS in download section but I thinks at the end you have to build a prototype and fine tune number of windings for your application.
Also you can take a look at TOP switches, like TOP225Y they are very easy to work with with least number of external components.