[time-nuts] Frequency referenced temperature regulator
brooke at pacific.net
Mon Nov 8 15:21:34 UTC 2010
Is there a source of crystals cut for temperature measurements?
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.
> 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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