James Sweet wrote:

Indeed this is true for modern versions, but DC Muffin fans from the 1960s
had brushes (electronic comutation would have been large and of
prohibitive
expense).




They had DC muffin fans in the 60s? I don't recall ever seeing one, what
were they used in? I've seen AC muffin fans powered by shaded pole motors,
and a few DC fans that were just a fan blade stuck on the end of a little DC
motor, but I've never come across one I'd call a muffin fan.



I knew you'd ask My recollections are from govt. contract gear that used
24 or 28 VDC fans. These may not have been "Muffin" brand fans but I am unable
to inspect one any more as the gear is long gone. Anyone else with these
recollections?

One remarkable fan that I wish I still had was the 400 Hz "Minicube" blower;
about one inch on a side, it could easily levitate or blow itself off of
the bench under power. These were used on F111A avionics boards (and no
doubt other platforms as well)

Michael