[ntp:questions] backup PPS source

David Lord snews at lordynet.org
Tue Apr 13 10:19:12 UTC 2010

pc wrote:
> Why bother with varicaps and pots when a DS3231 chip will probably do
> what you want
> straight out of the box? Or are you thinking that you might have to
> trim out a
> constant frequency offset?

Unfortunately these aren't available from my regular supplier.

 From Farnell, Unit Price: £9.49, then add a not insignificant
delivery charge.

I might try to blag a free sample as Maxim are quite good for

 From first look at datasheet:

I'm not familiar with i2c so something else to learn
although won't be wasted.

Claimed accuracy is 120 sec per year and at moment I seem to
have about 10ms per day = 3 sec per year without compensation.

I think applying some correction from a GPS when available
would be trivial for someone more familiar with programing
these things.

At moment I have zener or LED to use as varicap, 10t pot,
smoothing capacitor and regulated supply all handy. My beer
brewing temp controller gives better than +/- 0.5C control
so intend giving that route a shot first.


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