Power supply transformer

A lot of good comments have come out on power supplies so I'm trying to put
one together.

It occurred to me to question whether you really need a 110 or 220 input
and 24 volt out. Seems to me that what I should be looking for is the
ratio of input voltage to output voltage. As long as the high side of the
transformer is rated higher than your AC voltage you should be able to feed
it. What you get back should be a voltage equal to the ratio of the coils.

So I went out to the shop and dug up some old machine tool control
transformers that I liberated years ago from stuff headed for scrap. I
found one with dual winding on the primary 220/440 with + or - 15% taps and
with 110 on the secondary. It's rated for 650va. Correct my numbers here
when I screw up.

1. Volts

My power line is 122 most of the time. (yes my filament life is short)
Feed line to the 440 side of this transformer and get 30.5 back. Peak
voltage should yield 43 volts DC. (rms/.707) Add the 15% up and I should
have a 49 volt supply.

The surplus steppers and centent drivers that I liberated from some x ray
equipment ran on a 48 volt supply.

2. Amps

I get real iffy here! 650 va divided by 122 tells me that I should limit
the AC side to 5.33 amps so I'll sugggest a 5 amp common fuse. (Someone
mentioned that a transformer is rated for continuous duty so it should do
more.) On the secondary side I should be able to draw four times that or
20 amps. (Isn't this limited by the wire size in the coil?)

3. Load

Centent tells me that their driver uses 1/3 of motor rated amps for series
connected motors and 2/3 for a parallel connected motor. Since each motor
is rated for 4.5 amps I should be able to run at least six of these 150
in/oz motors (18.09 amps) from this transformer. Wow six axis! I could
run the table top nist hexapod.

I plan to pile all this stuff on the basement table (I don't have a
hexapod) and try it with my EMC software in the next couple of days so
correct me where I'm wrong or the significant other will rush down the
basement stair yelling, "I SMELL SMOKE!"

Ray