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.
