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 <bro...@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"<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. >>> >>> _______________________________________________ >>> time-nuts mailing list -- time-nuts@febo.com >>> To unsubscribe, go to >>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >>> and follow the instructions there. >>> >> _______________________________________________ >> time-nuts mailing list -- time-nuts@febo.com >> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> and follow the instructions there. >> >> >> > > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.