Hal, For science-fair level accuracy try a $2 PTC-60 thermistor heater one component oven for minimal complexity. I tried this with a small box and insulating foam and it gives surprisingly good results. Leave it to the ham radio guys to come up with a low cost solution.
http://www.setileague.org/askdr/xtaloven.htm Richard > >>> Junk crystals are good thermometers. Ballpark is 1 ppm/degree-C > > albertson.ch...@gmail.com said: >> So does this mean I can epoxy a sandstone power resister to a junk crystal >> and keep the frequency exactly perfect by varying the power in the resister? > > Sure, for some values of "perfect" and such. > > I've occasionally thought about building something like this, just for the > hell of it to see what happens and/or what I learn, and or how good I/we can > get on a low budget. > > I think there are two problem areas. One is sensors and control algorithms. > The other is board layout. > > Where is the sweet spot on complexity vs accuracy? I'm looking for > science-fair level of goodness rather than super-expensive to get another 0 > or two. > > What's the best low-cost way to measure temperature? Many of the obvious > choices are only good to 0.1 C. That's great if you are trying to measure > room temperature or or want to keep your CPU from melting, but it's probably > leaving a lot on the table if you are interested in the frequency from a > crystal. > > My straw man would be a thermistor and OP-Amp feeding into the ADC on your > favorite uProc. Maybe the other side of a bridge would be adjustable. > > How much power do you need to keep things warm? I'm assuming something like > a watt or 2 with something like a PWM from the uProc. > > > -- > These are my opinions. I hate spam. > > > > _______________________________________________ > 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.
