As Inretech said, but the inductor plays quite a large part if it is not matched properly. And anyway, for hobbyists, I think we can simplify it a little.
When I started making my own inductor coils, I had a little Neosid ferrite core. What I didn't realise was that Neosid had specified this core for low frequency applications. The flyback inductor I built was high frequency. Needless to say, there were huge losess due to hysterisis (NOT hysterics /ubbthreads/images/graemlins/smile.gif ). I was disappointed with the results. Only when I switched to one designed for high frequency...
Hysteresis losess are due to the fact that ferrite (or iron) can be magnetised if you apply a direct current to a coil wound around it. But in a transformer or inductor or similar device, the current is AC. So for one moment, the core is magnetised in one direction. The next moment, the core is magnetised in the other direction. It takes energy to counter the original magnetic direction before the core can be magnetised in the new direction.
Also, an inductor delivers its power as the magnetic field it was induced with collapses. What would happen if the magnetic field in your core didn't collapse completely? You wouldn't get as much power as you could, since it is that magnetic energy that is "fueling" the electrical pulse.
These are simple explainations for hysteresis. Also, with regard to design, there are also considerations for eddy currents, core losess, imperfect coupling, etc.
Generally, for power supply designs, you want a ferrite core designed for high frequencies to reduce hysteresis losess, closed loop (toroidal) and without chips or cracks to reduce coupling losess.
Beyond that, you need those complicated maths to work out the size of wire, size of core, type of core material, number of turns or wire in which direction, and even where to place those turns. And that, IMHO, is beyond the realm of hobbyists like me. /ubbthreads/images/graemlins/tongue.gif
I hope that explaination came out correctly and clearly. /ubbthreads/images/graemlins/smile.gif
