Patrick Turner" wrote

...But a toroidal winding machine has a circular shuttle in two halves which
is clipped
together through toroid hole
and rotated on rollers to load it up before winding the wire back onto the
core.
It is labour intensive and slow, but 20 times faster than the broom handle
shuttle.

Quite, as I have just explained, except for your use of the word "shuttle".

The essential thing about a shuttle is that it goes backwards and forwards. What
you describe here is not a shuttle. If the bobbin were repeatedly passed through
the hole in order to wind the wire onto the core, it would be a shuttle of
sorts, more or less, but it doesn't, it simply turns on its axis. "Spool" would
be a less misleading term.

It is not necessarily labour intensive. It can be machine-intensive instead. How
quick depends on how many machines or people are on the job, and how fast they
work. It would generally need to be more than 20 times faster than the broom
handle shuttle.


...The E&I are wound with 2 concentric bobbins, primary on one and any
assortment of
secondaries on the other,
and large numbers of bobbins can be wound at the same time.
The cores are high grade GOSS with max µ = 17,000 if they were fully
interleaved,
but they are
not interlaved at all and a block of E and block of I are placed around the
assembled bobbins by machine and
welded with machine welding machines. The resulting µ of the material is
sufficiently high to
give low iron losses. This production method is very cheap compared to
anything
else...

Perhaps this kind of construction partly explains Robert's observations using a
cheap power transformer for SE power output.

cheers, Ian