I think you might find a "wall-wart" power supply for a computer printer
to do the job.

You can find these in voltages like 24-28v @ 1 amp for maybe $10 new in
the US. Of course ours are 120v but I imagine you have the 240v types
available over there in I-land.

-Bill

Thank you Bill, but i want to start from 12/13,8 vdc to reach the famous 24
vdc, and do not want to use a 120 or 220 vac supply...

73 de Riccardo IK5WQO