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"<p...@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
p...@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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