A note in defence of the much maligned Altair while on
this subject...
May I point out the the Altair 'B' series machines were one of the first to
provide a main transformer with a multi-tap primary to allow for adjusting
for varying loads and local AC supply.
And by this point in time ferroresonant transformers were also being
dropped in by folks who weren't happy with the original supply, either.
Having used a large variety of S-100 boxes, far and away my favorite
power supplies are ones with ferroresonant transformers.
Tim.