[time-nuts] Low power timekeeping

[Alan Melia]

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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