[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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