This is handy:
http://schmidt-walter-schaltnetzteile.de/smps_e/smps_e.htmlNote that it defaults to CCS (small k), just enter a different inductance and turns ratio manually to operate differently.
You may also find a forward converter is handy, just because of the low output voltage and high peak current. This can also operate in, or near, DCM, where peak current mode control is still easy, and where peak output current is lessened thanks to the filter choke.
The concern with peak current comes from the quality of the capacitors. Low-ESR capacitors are readily available today (you can choose aluminum polymer types if you want -- these have comparable quality to film capacitors, but operate at much lower voltages!), so it's not such a big deal. Just be careful if you're doing it with salvaged parts, or cheap parts of unknown rating -- you may find far more output voltage ripple, and much more capacitor temperature rise, than you were expecting!
FYI, be careful with mains inputs. Use an isolation transformer, of course, but also start small -- especially if you don't have any experience in this yet! Make it for 12 or 24V input first, and make it work well. You will learn every lesson you need, there. Then you can increase the input voltage.
Set goals for yourself. Create stages in your project, with clear expectations and outcomes. Don't make it too rigid -- you don't know what circuit changes may be needed, or if you can satisfy certain criteria -- specifications may need to change as you realize what their consequences are.
And, don't neglect EMI checks. Read up on how and why testing is performed, and obtain a LISN (you can build one from junk without too much trouble) to do basic testing. It's not going to be regulatory grade, but that's okay, you don't have a test chamber and calibrated antennas anyway. Just a precompliance test.
Tim
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