[time-nuts] Frequency referenced temperature regulator

[John Ackermann N8UR]

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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