[Alex] ramped up the precision of his timepiece by adding a ChronoDot to the Ice Tube Clock. These two items are among our favorites; the Ice Tube Clock for its old-style multi-digit display, and the ChronoDot for combining a DS3231, battery, and components into a nice small package.
There is a schematic link at the very bottom left of [Alex's] writeup. He mentions that he depopulated the clock crystal and its capacitor pair from the board and patched into the clock input on the AVR. A 100K pull-up resistor is included in the wiring as called for in the DS3231 datasheet. Although not specifically referenced, we assume that [Alex] reprogrammed the ATmega168 clock select fuses to use an external clock signal.
Now he can sit back knowing that the clock will be within 10 seconds per year accuracy.
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I went for harder solution by building xtalOven
Why not measure the decay of a cesium atom?
Man you hackers are getting lazy.
Last time I checked, the DS3231/DS3234 has +/-2 minutes per year accuracy. Where did you get the 10 seconds figure?
The IceCube clock already uses an external clock. there was no reprogramming required. Yes, sorry, less than a minute a year
A timely hack!
(ducks)