On Wed, 30 Mar 2005 09:09:40 -0600, you wrote:

>I'm trying to modify Roman's 2-transistor SMPS circuit to make a 150 to 5
>VDC converter and I can make it work but I am dissipating a lot of power in
>the transistor base resistors.  I tried to find a high voltage PNP
>Darlington to help with this but I have little luck finding one.  I did the
>classic Google and datasheet searches but seems the highest I can find is
>around 40V.  I really need one that is rated at least at 240 Volts or so.
>
>I'm only looking at supplying a max of 100 mA.  Anybody know of a source
>for a high voltage PNP Darlington that I could use in this application?
>Anyone ever try a FET with Roman's SMPS???

Why not just use 2 transistors in a darlington configuration ? 



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