BA23 fan noise

[Jon Elson]

On 01/31/2016 08:42 PM, Mark G. Thomas wrote:
> Does anyone have any suggestions for figuring out how much airflow I
> actually need, and achieving it with either stock fans at further reduced
> voltage, or some kind of replacements? I don't need an accurate solution,
> or something with complicated compensation for varying temperature,
> just something quieter, moving less air, but still enough air.
>
>
I may have cooked some peripheral boards in my homebrew uVAX 
cabinet.  The KA630 seems pretty robust, it ran for 21 years 
continuously under these conditions.  I got an EBM motorized 
impeller and made up my own plenum.  The AC motor ran it WAY 
too fast, so I cobbled an 8" floppy brushless motor onto the 
original impeller, and I could adjust the speed.  My main 
test was to let it run an hour and see if the air coming out 
seemed too warm.  This was pretty unscientific.  The only 
boards that croaked were Dilog and such 3rd party boards.  I 
did have a thermal safety system that would cut power if the 
cooling failed (which it never did).  I later got a 
tangential blower for the expansion backplane, and it was a 
good deal quieter, but maybe didn't move enough air.

Jon