need physically Small power supply from high DC voltage

Railroader:
Well done! 80 volt is good. What does absolute maximum ratings say? Possible to modify to 85 V?

Buying existing equipment is very actractive and often cost effective. Once I built a step up converter, from 5 or 12 v to 25...…..

Found the datasheet for the reg, based on the pictures ... an XL7035 by XLSEMI

Vmax is 85V. (80V is recommended as max. for normal operating)