Hi there, I want a lower of 110/120vac power from 240vac main, I was thinking of removing the secondary coil of microwave transformer and rewind it with a 0.5mm stranded wire. keep checking with multi-meter till I got around 110/120vac. The problem I don't know about the current as I don't have a clamp meter to check. Is this way will work?

 

A simple way to determine turns/volt is when you have removed the secondary, wind 10 turns on, measure the voltage and extrapolate the T/V from this.
Use double the wire gauge of the primary for the final secondary winding.
Remove/drive out any magnetic shunt bar that is originally fitted.
Max.

 

Be aware that the microwave transformer may be rated for short term use only and could self-heat under prolonged use.

 

Here is a link fr re-purposing M.wave Tfmr.
Transformer
Max.

 

OK thanks