Hi,
am am thinking about building a small supply of regulated DC 250V 5 mA
from a 12V DC input. Does not have to be isolated, but the supply should be filtered and regulated (does not have to be very well regulated though). Probably flyback converter, I think it is a too big voltage difference (ratio) for a simple boost converter with one inductor. I have found specialized ICs and design wizards but they do not manage with such a high output voltage, usually common flyback designs are downconverters for off-line switched power supplies.
So any idea for a simple design ? especially the flyback transformer design ?
Thanks,
Petr