[time-nuts] Low power timekeeping

David McGaw n1hac at Alum.Dartmouth.ORG
Thu Sep 27 18:45:35 UTC 2012


It is not a matter of skin depth.  Skin depth relates to a dissipative 
process like EM waves traveling into/through a resistive medium.  Soil 
and rock are not dissipative to heat in this way. There is a poor 
impedance match between the air and the soil but once into the ground, 
through soil and rock you can have propagating thermal waves.

David


On 9/27/12 1:07 PM, Alan Melia wrote:
> Hi Chris when the British Post Office (later BT) ran radio stations, 
> the station standard was usually in a hole 30 feet deep. Crystals were 
> made in our own "Factory", a section of the Research department, so 
> the crystals would have been cut to suit UK conditions. Maintaining 
> systems were usually Meecham Bridge and the crystals most probably 
> Essen rings which are fairly massive bits of Quartz.
>
> Alan
> G3NYK
>
>
>
> ----- Original Message ----- From: "Chris Albertson" 
> <albertson.chris at gmail.com>
> To: "Discussion of precise time and frequency measurement" 
> <time-nuts at febo.com>
> Sent: Thursday, September 27, 2012 4:46 PM
> Subject: Re: [time-nuts] Low power timekeeping
>
>
>> 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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