You will have to give us more information on where you are at on your design and what exactly the problem is. There are many ways that this type of power supply can be designed. There are also a lot of ready to go switching supplies that are available. Did you see the listing the other day from Recom. They have a book that covers a lot of the basic about AC-DC and DC-DC converters. Here is the link in case you want to check it out.
thanks for the valuable reply, i am building a automatic water pump switch which contain controller circuitry with lot of passive components. Actually i was using a pre-designed SMPS with my application earlier but unfortunately that got burnt 3 times, so after that i decided to build one by myself
It sounds like a really interesting project. Please keep me posted on your progress. Sorry the predesigned supplies burned up. I often find I have to modify things to get them to work the way I want them to.
