[time-nuts] Thunderbolt mounting

Magnus Danielson magnus at rubidium.dyndns.org
Thu Jul 12 13:28:26 UTC 2012


On 07/12/2012 03:22 PM, Jim Lux wrote:
> On 7/11/12 7:00 PM, Mike S wrote:
>> On 7/11/2012 8:15 PM, Chris Wilson wrote:
>>> Does anyone know if there's a means to log max and min temps for these
>>> things? I was going to make a crude box for mine out of 2 inch cavity
>>> wall
>>> insulation hard foam,
>>
>> The TB reports it's own temperature. Lady Heather will track it.
>>
>> I'm surprised no one has mounted one to a Peltier cooler, and stabilized
>> the temp with PID control, based on the self-reported temp. Why not run
>> it cooler than ambient? I'd assume a simple microcontroller could handle
>> the task, but don't have any deep PID control knowledge myself.
>>
>
> PID controller code for Arduinos and the like is readily available..
>
> However, as to why not run it cooler?
>
> The internal oven tries to keep the crystal at the temperature where the
> frequency vs temp curve has the lowest slope. If you cool the outside,
> then you just burn more power in the internal oven.

You can run it at higher temperature if you maintain that actively. 
There is a balance between elevated temperature and shorting of life 
that way and elevated oven current and shorting of life that way.

Whatever cooling mechanism used (and a PID controller is a good start) a 
linear control is recommended.

Cheers,
Magnus




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