There are many small buck converters available on ebay (ex China) at
astoundingly low cost. Typically ~=3D 30v or sometimes more in and adjustab=
le
across a wide range of Vout. These too would need to be "smoke tested" for
reliability but generally should be OKish.

Increasing Vfeed by N times decreases current by 1/(N x efficiency) so eg a
25V in 5V out feed may reduce current to  say 5/25 x 1/75% or about 25% of
original. Heating capability decreases with N^2 so this may also help with
fire risk.

Also, some but not all switching modules will fold back on short circuit or
gross overload.
Which do and which don't is left as an exercise for the student :-)



            Russell
--=20
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