[time-nuts] Frequency referenced temperature regulator

John Ackermann N8UR jra at febo.com
Mon Nov 8 16:26:02 UTC 2010


I've never looked.  The original HP Journal article talked about the characteristics of the crystal.  I think it's called an L cut.  The frequency used was around 26 MHz because that yielded an easy Hz/degree ratio.

On Nov 8, 2010, at 10:21 AM, Brooke Clarke <brooke at pacific.net> wrote:

> Hi John:
> 
> Is there a source of crystals cut for temperature measurements?
> 
> Have Fun,
> 
> Brooke Clarke
> http://www.PRC68.com
> 
> 
> John Ackermann N8UR wrote:
>> Sounds like the way the HP 2804 quartz thermometer works.  HP came up with a special crystal cut that was very linear with temp, and I suspect the hardest part of your idea might be the linearity of the tempco of your crystal.  But you could characterize that and store in a correction table.
>> 
>> John
>> 
>> On Nov 8, 2010, at 10:04 AM, "Poul-Henning Kamp"<phk at phk.freebsd.dk>  wrote:
>> 
>>   
>>> I'm contemplating building a small temperature control enclosure for
>>> testing various electronics.
>>> 
>>> I have a handful of peltiers suitable for the purpose, and was
>>> pondering the right control mechanism.
>>> 
>>> Most people would reach for a NTC, put it in a wien-brige etc etc.
>>> 
>>> But since I happen to have access to much more stable frequencies
>>> than voltages, I thought of a different way:
>>> 
>>> 1. Mount a X-tal-osc with really lousy tempco inside the enclosure.
>>> 
>>> 2. Compare its output to a stable reference frequency.
>>> 
>>> 3. Use the output of the phase comparator to drive the Peltier.
>>> 
>>> It is basically a PLL where temperature is used as EFC...
>>> 
>>> Has anybody tried that ?
>>> 
>>> -- 
>>> Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
>>> phk at FreeBSD.ORG         | TCP/IP since RFC 956
>>> FreeBSD committer       | BSD since 4.3-tahoe
>>> Never attribute to malice what can adequately be explained by incompetence.
>>> 
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>>   
> 
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