Hi Glutnix, and Ron
Yes, a tapped inductor is really just two inductors in series, effectively having a 'tap' somewhere in the middle of the inductor with a ratio of turns. It's also refered to as a 'coupled inductor'. Essentially an autotransformer. Perhaps I'm off but I see it as a flyback with the hot side of the secondary connected to the cold side of the primary. Such as in this link:
**broken link removed**
EDN PDF
**broken link removed**
A standard boost converter is really not up to the task of >150V from a 12v input, as glutmix pointed out, the MOSFET not only needs a high voltage rating for flybacks but for boost converters with a 200v output, one would need a good 600V MOSFET, which increases on resistance, hence, lowers efficiency.
Ron, I don't want to power this with 1.5V, m ypoint was many schematic on the internet use designs from dispoaible camera which use single AA's. I'm after much more power, and greater efficiency. Input should be 12V, with perhaps a maximum of 1A continous. I know strobes use autotransformers for the trigger, but rarely for the actual step up converter.
Really, I'm completely confused and somewhat indecisive as to the best topology for this sort of system: Charging 300V caps. Since the output is a current source, not regulated. So continuous frequency PWM would probably be a bit inefficient.
Flybacks have their place, and I can wind my own, controlling the airgap, inductance and turns ratio (perhaps using peak current limiting) but tapped inductors, although pretty much modified boost converters, appear to ease some of the high voltage burden on the mosfet switch.
Perhaps I shall just need to wind some transformers and do some measurements
As I often over think things in my quest for perfection and easily get swapped in idea's and possibilities.