Poul-Henning, On 11/08/2010 04:04 PM, Poul-Henning Kamp 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 ?
Have a look at "microprocessor compensated crystal oscillators". It runs the oscillator in both basic and third overtone at the same time. By measuring the beat frequency between the modes, the temperature can be measured.
See the John Vig presentation http://www.am1.us/Papers/U11625 VIG-TUTORIAL.PDF starting at page 43. I see no reason why it could not be used to stabilize the temperature. Cheers, Magnus _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
