I would usually be able to work this out but due to some pre-occupations I have to depend on your help.

A toroidal transformer has:

- 2 primary coils rated at 115V each

- 2 secondary coils rated 25V each

What I am trying to do is find a toroid transformer with the right combination such that I can achieve 230V to 115V step down. Now for this to happen, very simply put, the primary coil must be half the number of turns as the secondary right. Meaning, if I connect the secondary coils in the above example in series and use only one primary, or both primaries in parallel, but instead of feeding 115V in to it I feed 230V, I should (given the numbers above) get 100V out right?

The ratio = 115/(25+25) = 2.3

Therefore Vout = 230/2.3 = 100V

Or will I burn out the primary coils because the current will be double what it was designed for?

Thanks in advance everyone.