Jeff Mock wrote: > Jeffrey Pawlan wrote: > >> On Thu, 29 Nov 2007, David Forbes wrote: >> >>> It might be more fun to require that an OCXO be designed and built by >>> the DIY-er out of commercially available crystals and resistors. That >>> way, it's an engineering challenge instead of a procurement >>> challenge, since IEEE is about engineering. >>> -- >>> >> I second David's suggestion! The only REAL challenge would be to design the >> circuitry. Otherwise this is just a "rack & stack" project which is not >> engineering. >> >> > > I think it's a fantastic challenge. I imagine starting with a design > goal something like tvb's original leapsecond goal. It would be kind of > cool to have a $100 clock that met that criteria. > > I don't think an off-the shelf OCXO timebase will be competitive at this > price point. I'm not aware of an inexpensive SC-cut oscillator. > > I think the parameters for the contest need to be tightened up. > Temperature and environment are enemies for this kind of clock, I hope > they specify the operating environment and time period for evaluation. > > I think that I would start by looking at 32kHz watch crystals, I've > often wondered how good a timebase you can make out of one. The tempco > is a parabola around 25C with a max slope of something like 0.05 PPM/C, > so they are naturally a pretty good timebase with good aging > characteristics. The crystals are really tiny, maybe insulating it with > a material that has an interesting heat of fusion along with a micro to > model the physics of the parabolic shape of the crystal performance. > > jeff > > Maybe an ensemble of watch crystal clocks and a PIC microprocessor per David Allan paper of some years ago. After testing you could assign deferent weighting to the different clocks.
Bill K7NOM _______________________________________________ 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.