Jack and ....,
I tried adding a fan very similar to the one pictured and it introduced a "whirring" noise into the audio that I could not get rid of. It was wired up to the main supply voltage via the main on/off switch. I did not try putting a regulator in front but did try various caps/filters/etc to no avail.
YMMV
P. J. Hicks, N7PXY
