[time-nuts] Chronometer contest sponsored by IEEE Spectrum

Jeff Mock 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
> 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




More information about the time-nuts mailing list