[time-nuts] Low power timekeeping

Chris Albertson albertson.chris at gmail.com
Thu Sep 27 15:46:34 UTC 2012


On Wed, Sep 26, 2012 at 11:05 PM, Hal Murray <hmurray at megapathdsl.net> wrote:
>
>> As you go deeper you get a delayed history of the surface temperature.
>
> Right.  Skin depth.
>
>
>> A good oven runs rings around deep earth stability.
>
> But a hole in the ground doesn't take any power.
>

That was my point.   At some depth you get less then a degree of
day/night and summer/winter variation.  That is very good for zero
power input.

Yes a precision controller could do better.  I onced used a Peltier
device with water heat sink all running in a vacuum insulated jar.  It
kept the temperature pretty much dead-on but at high cost in bulk (55
gal.drum of coolant)  and plumbing and in power.  But you get 0.3C
error for free and it runs for years on "nothing"   It's a trade off.


Chris Albertson
Redondo Beach, California



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