[time-nuts] Thunderbolt mounting

Chris Albertson albertson.chris at gmail.com
Sat Jul 14 00:32:50 UTC 2012


I've got a foundation trench open right now.  I've been thinking it is a
great opportunity to keep some electronics at a very stable temperature.
 What's better then tossing it in a big hole in the ground then dumping a
truckload of concrete on top?   Likely the only thing I'll burry is a $2
temperature sensor.  In So. California you don't need to go very deep to
reach stable temp.




On Fri, Jul 13, 2012 at 5:25 PM, Neville Michie <namichie at gmail.com> wrote:

>
> You have to go deep into the ground to get stability.
> At 15 metres deep there is a lovely pure sine wave of about 0.3C P-P.
> I measured it on the roof of a cave, its period one year.
> My design for the bolt is to put it in a 1/4 inch thick aluminium box which
> is held at a constant temperature by a fan. Switching control is good
> enough as the
> thermal diffusivity of 1/4 inch aluminium will attenuate any spectral
> components shorter than
> a minute. The aluminium box is so conductive that the box is isothermal,
> so once the bolt
> has established its internal temperature gradients, nothing changes.
> cheers,
> Neville Michie
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-- 

Chris Albertson
Redondo Beach, California


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