I second that! I too would really like to see
how a simple 2-tran circuit handles the 4A load.
-Roman


Russell McMahon wrote:
>
> > > > Actually the normal draw on the 5V line is about 4A. I measured it
> during
> > > > testing of Russell's 2 transistor SMPS. BTW the MB would consistently
> boot
> > > > from that power supply.
> > >
> > > I'd like to see the circuit you built, i'm curious
> > > about the regulation and also the type and performance
> > > of the inductor.
> >
> > Let me know what you want me to measure.
> >
> > The inductor is a J.W. Miller high current toroid pushed from
> RadioShack.com
> > IIRC it's a 50 mH 10A inductor.
>
> What would be interesting would be
>
> 1    Output voltage at a number of combinations of input voltage and output
> current.
> 2    It would also be interesting to know input current as well in each
> case.
> 3    For the really keen,  the performance under sudden steps in load and
> input voltage would be of interest.
>
> 1. is best presented as a table with Vin and Iout as table axes and Vout for
> each combination.
>
> I found my original design to have amazingly good Vout regulation with Vin
> and Iout CONSIDERING HOW SIMPLE THE CIRCUIT IS. I "shout" this as I don't
> want people to think I am saying it is a high performance design in absolute
> terms compared with sophisticated IC based designs - just amazingly good for
> what it is. For example, *from memory*, with Vin ranging from about 12 volts
> to 200 volts I was getting Vout of better than +/- 0.1 volt. Can't remember
> regulation with load but can always measure with a working design or dig up
> notebooks if of great interest. Byron's figures would be more apposite in
> the present case.
>
> 2. above allows efficiency to be determined.
>
> 3. - transient performance (scope or similar needed) allows you to determine
> if there are any nasty surprises lurking. An apparently well performed
> design may provide a voltage spike on step removal of load (or on
> application!)  or Vout may drop substantially during load changes.
>
> regards,
>
>         Russell McMahon

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