Can I use an air core toroidal transformer instead of ferrite?

Question

There are no cheap ferrite toroidal cores available to me, what is the down side to just using an air core or some sort of non magnetic core? Is it just efficiency?
I want a 230V input and ~70-0-70 output about 500VA

J. Frost · Accepted Answer

you can but you wil need an impractical number of turns! The core does two important things: it ensures that all the flux from one coil links the other, and it makes the reluctance of the magnetic circuit small, so the magnetising inductance is very high. The higher the magnetising inductance, the lower the magnetising current. An air cored transformer for mains frequency power is completely impractical.

Water Pitcher · Answer

hysterisis is the issue and don't see it mattering here.

(update) i was wondering why he would use air core, at 500W didn't seem to make much sense. ferrite core is going to be smaller, but there is some loss and heat in the core, from the hysteresis, maybe what he meant by efficiency. that's the issue: size (number of turns) versus loss in the core.

Can I use an air core toroidal transformer instead of ferrite?

2 Answers