DIYbanter - View Single Post

Ralph Mowery

In article ,
says...

The auto transformer is isolated by another transformer all in the
same case.

Do they really need two transformers? Sounds like a lot of redundant
iron and copper.

Could they not use one normal (isolated) transformer and then have
contact wiper move along the secondary winding?

I am sure they could. The problem is just geting one made. They
probably just took 2 transformers that are already on the market and put
them together. Less expensive than making just a few thousand of a new
design.