[Avodah] electronics on shabbat

[Marty Bluke via Avodah]

In the sefer Hachashmal L'Or Hahalacha he assumes as a davar pashut that
a light with no heat is not mav'ir and is only an issur drabbanan, see
http://www.hebrewbooks.org/pdfpager.aspx?req=8812&st=&pgnum=149&hilite=
at the bottom of the page where he discusses small fluorescents which
have no heating element. Unfortunately, he brings no source for this
assumption, it seems like it was just obvious to him.

See also http://www.torahmusings.com/2016/08/led-shoes-children-shabbat/
where R' Mann writes that the consensus opinion is that LEDs are not an
issur d'oraysa, again unfortunately no source is quoted.

"The consensus is that activating light-emitting diodes (LEDs) on Shabbat
is not a Torah-level prohibition, but is a Rabbinic level one. One connects
a circuit and light is emitted (by the transfer of electrons through
junctions of semi-conductors). It is not simple to pinpoint what the
Rabbinic violation is (when the diodes do not form writing or pictures).
Some (including Rav S.Z. Auerbach) say it is *molid*(creating something
new), even though there is no explicit Talmudic category of *molid* with
light. Others say it is under the category of *uvdin d’chol*, which is a
sort of catch-all for things that by halachic intuition and precedent, must
be forbidden on Shabbat, which we assume regarding operating electric
systems on Shabbat."