Re: [ATM] Coolling fans for mirror

["John Sherman" <atmer@johnspics.com>]

Hi Dale,


> Usually we want to cool the mirror to ambient as fast
> as possible so that we can get the best view soon.

Absolutely!

> Overall a single small fan
> supported on rubber bands aimed at the back of the
> mirror is a very good way to cool the mirror quickly
> and has been used successfully by many.

It's my favorite way of ventilating. Also it takes advantage of the tendency 
of heat to rise. But I hate the rubber bands, they quickly dry out and fall 
apart. I now use a sheet of felt. They are in craft stores, about 12" x 12" 
x 1/8". I cut a hole in the center and mounted the fan to it with little 
bolts, then screwed the corners of the felt to the mirror box. I also attach 
the switch and pot to the felt, with all the wiring hidden inside. It 
deadens vibrations better than rubber bands, and it lives much longer. Also 
it helps prevent a backwash of air (so that air is forced around the mirror 
and up the tube better), and helps block light from entering the back of the 
tube.

Happy observing,

John









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