[time-nuts] Chronometer contest sponsored by IEEE Spectrum
jeff at mock.com
Thu Nov 29 14:50:45 EST 2007
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
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.
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