Isolating transformer

This is my 600 VA transformer for secure works with 230V AC.

The aluminum case has 38 cm x 27 cm (15 x 11 inch).

The toroidal transformer is clearly visible.


  • Very less magnetic leakage flux
  • No air gap  ->  No magnetic resistance  ->  Small “no load current”
  • Looks good


  • More difficult coil wrapping

Known issues:

  • The coil has no shielding.
  • Primary and secondary coil are maybe not in separated winding chambers.
  • The capacity is not known.


The black cable on the left is the 230V input.

The circuit breaker is for turning on/off and it has a built-in fuse for max. 10 A.

I use two junction boxes. As a result, a contact is impossible.
The right box has a 3 A fuse inside.

Two output sockets.