16 Apr
2009
16 Apr
'09
3:22 p.m.
On Wednesday 15 April 2009 12:25:53 pm Tony Duell wrote:
I have some power supplies -- out of an IBM storage setup or similar -- that
use fans that operate on an odd voltage like that. I get the impression that
they chose that voltage as being the maximim input for some 3-terminal
regulator part on the other end.
--
Member of the toughest, meanest, deadliest, most unrelenting -- and
ablest -- form of life in this section of space, a critter that can
be killed but can't be tamed. --Robert A. Heinlein, "The Puppet Masters"
-
Information is more dangerous than cannon to a society ruled by lies. --James
M Dakin
I've found
pictures on the 'net of the fans - looking at the wiring,
they appear to me to be pretty standard 110VAC boxer fans. ISTR
hearing that the fans in the 11/40 or 11/45 are bizarre, but I'm
The fans in an 11/45 are plain 110V ones (even in the UK, they're run off
the primary of the mains transformer acting as an autotransformer). I
suspect the 11/40 is the same.
It's the 11/44 (a much later machine) that has odd fans -- 35V 70Hz or
something. They run off a transistorised full-H driver circuit in the
PSU, so they can be run off the backup battery. expecting that
the fans in the 11/20 are ordinary. This leaves the
PSUs. If I were going to go with MOS memory, I wouldn't worry about
what to use - the Unibus itself only needs to provide +5V, and +/-15V.
Because the 11/20 routinely held core, it's expecting +8V (unreg)
plus -22V on top of the usual voltages.
You may find that +8V is used eleewhere. I remember a +8V supply for the
lamps on the KM11, and it may be used by the front panel lamps.
-tony