This is an experimental circuit, using a small transformer to drive P-channel MOSFET, using
a LM2576 adjustable regulator.
Powered by 12V electronic transformer, having a cooler fan for the P-channel MOSFET,
and input voltage can be as high as 60 volts (and more). 50V here for the test.
Output is adjustable. Power test was done with 12V/50W halogen bulb, 4.16 Amps current.
Actually it can not startup at full voltage, since the LM2576 has overcurrent protection which still works
even through the control transformer. To start the 12V bulb, at first voltage must be reduced, then increased again to 12V.
For smaller bulb, 35W, this works automatically. Like a built-in softstart!
The coil is not well matched neither the control transformer, and the gate drive is crude, just the transformer secondary.
Efficiency is about 70%. The TO220 MOSFET is mounted like DPAK, to give best contact for the cooler.
the TO220 power diode also needs a small cooling grid at 4.16 Amps, and gets hot!