Perhaps that was a deterrent in popularity more than just their hard to wind
costs. I usually dealt with them as current transformers and inverter power
supplies mainly with their small ferrite cores, some with laminations, some
split core laminations (So they could be opened for insertion of conductor)
but they were harder to make to real accurate ratios (think clamp-on)

--------------
wrote in message ...
High inrush current is a problem, particularly on larger torroidal
transformers