Hi Eric
hi Hal,
I agree with RCinFLA, even though the xtal is at a fairly constant oven temperature it will still be subject to long term drift as will the supporting components.
>>Yes and I may have to manually reset the clock to Internet time if the error gets too much.
All the oven does is is to keep the xtal at a steady temperature which is higher than the highest expected ambient temperature and so avoids the change in xtal frequency due to changes in ambient temperature.
>>But if I understand correctly, it will probably run fairly true to its frequency with a constant error. The constant error should be able to be averaged and adjusted with a adding or subtracting ticks with a resettable input to a cmos 4029 (this may require a bit of hokey pokey with anding or norring but should be doable) once a time error is established and quantified.
With regard to any software program claiming to make a xtal PIC clock super accurate, that is only effective if the xtal remains on a precise frequency.
>>Not applicable, I have never used a pic.
Also presetting the xtal frequency at a precise frequency for long term time keeping is not easy.
>>I do not think that bending/tuning the frequency of a TF xtal is an easy option so I think it is easier to work with the natural frequency of the xtal (whatever it is with its inherent errors in the oven) and use the 4029 presets to adjust the actual “read out” time leds
I would go for a simple GPS unit for accurate time keeping.
>>The clock will be indoors and I thought that GPS requires a satelite view. Perhaps there are other ways to introduce a GPS signal that I am not aware off. I do not want a computer connection.
I was building and using xtal ovens for equipment back in the 1970's.
>>I was working on Weapons Radar sets in the RAN in 1970 (mainly valves)
Which makes us around the same ripe age of 60 + some or a lot
Eric, thank you and others very much for your advice. I really do appreciate it..
My next step is to order some parts and work on the oven part.
There will be plenty of questions later .
This project may take quite a bit of time, but thats Ok I'm retired.
Cheers RH