Re: Real time? and OT power supply

[Jon Elson <jmelson-at-artsci.wustl.edu>]

bfp wrote:

> the silent workstation idea is just a way to recycle an old 486SuX-33
> as a network terminal  ,its fast enough for text editing and web browsing
> with the QNX demo disk or a Linux equivalent but it will be in a room that I
> want quiet so I've pulled the hard drive and the only fan is in the PS
> its a Compaq with proprietary power connectors on the motherboard
> so it would take some minor testing and surgery to swap supplies
> the PS fan runs off the 12v rail and if disconnected the unit will not work
> at all (normally this would be ok) the power requirements are minimal
> with no hard drives to keep spinning and only a network card on an
> 'all in one' motherboard it would just have to run the floppy drive for
> a few minutes at bootup and run from ram the rest of the time

I think you really need some air circulation in the box.  But, there ARE
some VERY quiet fans.  One trick is to use a bank of DC brushless
fans at less than rated voltage.  You can put a couple of diodes in series
with the power leads to the fan.  If you run a 12 V fan at 8-9 volts,
it gets pretty quiet.  A couple fans running at this voltage might work fine.
I have seen some ETRI fans that were practically silent - somewhere
around 17 Dba!

Jon