Super simple high voltage (try it!)

[TurboSuper]

You're both right; a simple DC-DC converter works with a single inductor, but when you want to get into serious voltages, you need a transformer.

http://www.maxim-ic.com/appnotes.cfm/ap ... mber/2031/

[Ragnarok]

Well, sort of. Actually DC-DC convertors or even AC-DC switching power supplies operate by first rectifying the input signal to DC (if it is AC of course).

As Turbosuper puts it, not in the case of the boost converter, which makes the boost converter very space efficent - and it's electrical efficiency isn't too appalling either, I've seen them get 80% efficiency on a boost of 12V up to 300V.

Now, this isn't a boost converter, but it does work on the same principle as what the OP has built - just on a tiny scale, for scraping all the charge out of a "dead" battery, and I thought it might be interesting to show you, that is if you've not seen it before:
http://www.bigclive.com/joule.htm