Show HN: Apple II clock using interrupts from physical pendulum clock

Re:Show HN: Apple II clock using interrupts from physical pe... by tvb on Sunday January 28, 2024 @01:29PM (#39168362)

Many pendulum clocks are capable of well under 1 ppm accuracy, which is better than many quartz oscillators. Here is a tour of clock precision by orders of magnitude:

http://leapsecond.com/ten/

Here is a world record setting pendulum clock from a few years ago:

http://leapsecond.com/pend/clockb/

Precision pendulum clocks are a very deep rabbit hole.

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Re:Show HN: Apple II clock using interrupts from physical pe... by zokier on Sunday January 28, 2024 @03:50PM (#39169672)

> The Shortt was the first clock to be a more accurate timekeeper than the Earth itself; it was used in 1926 to detect tiny seasonal changes in the Earth's rotation rate. Shortt clocks achieved accuracy of around a second per year

If my math is right, thats about 30ppb

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