Here we have several strong willed people (N against 1 - not usually 
very fair) with good ideas talking past each other, failing to 
understand what the other person has said, missing the good points the 
other has offered, being gratuitously rude to each other, incorrectly 
criticising technical input from the other person and generally having 
a good time.

Why not start again and try a little harder. All can learn from this 
technically ( if not socially :-) )

Bob may yet learn that SMPS is not a total swear word and that what he 
is proposing has SOME similarities.
And 'we all' may realise that Bob is proposing a not new but less 
familiar technique which may be very useful on occasion and which is 
being used extremely successfully in some large real world 
applications.

A confusion is that bob has used the term "phase control" consistently 
when it's not phase control as our mothers understood the term. The 
method simply consists of PWMing an input (usually mains) 50/60 Hz AC 
waveform so that its amplitude is effectively reduced. The reduction 
is NOT achieved by converting to DC and then using high frequency Ac 
to reconstitute the waveform. There is no intentional flyback or 
energy storage at high frequency in the following transformer. The 
chopped AC is either filtered before it gets to the mains transformer 
OR the chopping rate is such that the transformer does not "see" the 
high frequency as the transformer acts as part of an low pass filter. 
There will be some issues with transformer response to high frequency 
components and back of envelope thinking suggests that there MAY be a 
need for some active flyback switching but the idea has merit and does 
overcome a number of issues not well addressed by other means. There 
is NO switching at the output side of the mains transformer and the 
output can see smooth sinusoidal 50/60 Hz AC if desired. Power factor 
is excellent.

The alternative to everyone starting again is that sooner or later 
(probably sooner) James gets mad and bangs some heads together. There 
have been "faults" all round. Why not try again with the extra 
information and understanding niow available?



        Russell McMahon 

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