ard at p850ug1.demon.co.uk
Wed Apr 15 11:25:53 CDT 2009
> 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.
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