Just some info regarding the thickness of the coil, you should have no more than 3A per mm (diameter of the wire) flowing through the wire. So if you were to connect your transformer to a standard 240V AC power point
* which gives 10A, you'd need a primary coil with a diameter of at least 3.4 mm.
If you have a lower power AC supply, like a 9V 2A source for example, your coil diameter is recommended to be at least 0.67 mm. For your secondary coil, calculate the current that you intend to pass throught it and from the ratio of diameter to max current, calculate the minumum diameter you should use.
* Don't do it, it's very dangerous and against the power authority regulations for you to stick your own unapproved & unshielded stuff into the power point . Use a low power AC source.