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SP6: Silent Desk Clock (accuracy test)

Here's some data that may be interesting concerning the accuracy of this clock thus far.

Clock with NIST, with the following results:

Clock Watch NIST Watch 8:00:00 8:00:00.00 8:10:00 8:09:59.38 8:01:00 8:00:59.89 8:11:00 8:10:59.42 8:02:00 8:01:59.99 8:12:00 8:11:59.39 8:03:00 8:03:00:00 8:13:00 8:12:59.24 8:04:00 8:03:59.90 8:14:00 8:13:59.39

Average of five measurements: 8:00:00 7:59:59.956 8:00:00 7:59:59.364

So the clock is now ahead of NIST by 0.956 - 0.364 = 0.592 seconds.

We started the clock speed test on 02/17/22 so now the results so far are:

03/04/22 02/17/22 Clock Time 07:59.59.956 12:00:00.176 NIST Time 07:59:59.364 11:59:59.774 Difference 0.592 second 0.402 second

So the clock is now ahead of NIST by 0.592 seconds and it was originally ahead of NIST by 0.402 seconds, so it has actually gained only 0.592 - 0.402 = 0.190 seconds in 03/04/22 - 02/17/22 = 14.83333 days. So the clock is running fast by 0.190/14.8333 = 0.0128 sec/day = 12.8 ms/day = 0.39 sec/month = 4.68 sec/year.

Your accuracy may vary due to climate conditions in your location, and time of year. We expect to do another calibration in a few months.

36 comments

36 Comments

normhuntley

Jan 27

I have finished the Silent Clock built the motor controller uploaded the ino to the Ardunio clock runs but second hand is gerty and the stepper motor is noisy.

normhuntley

Jan 28

Replying to

What else do you need the clock keeps good time I built the motor controller took the txt file and made it an ino loaded it to the Ardunio attached it to the stepper motor the second hand is jerky and the stepper motor is noisy. Steve for 20 years I owned a company that built and programed engine controllers for the $1000,000.00race cars we sold, I have 3 master's degrees all to do with the Automotive industry. I have built all four of your clocks three of them work awesome. I am 84 retired.

normhuntley

Jan 21

Steve which stepper motor did you use in the silent clock

normhuntley

Jan 17

Got the txt converted and uploaded to the Nano board

normhuntley

Jan 17

Steve having problem changing txt to a sketch surly you have a sketch that you can send instead have the clock finished and ready to run. thanks Norm

normhuntley

Dec 10, 2022

Steve I was wondering if you could send a sketch for the Arduino instead of the Algorithm, having problem getting it to cut and paste.

rcwhisnant

Mar 04, 2022

Our thermostat keeps our temperature very close to 74 degrees. So that probably helps the stability quite a bit. We did make the measurements visually, but for every measurement we took five and averaged to get a little better fractions of a second. We used a stopwatch for both the clock measurements and the measurements of the NIST time standard signals at https://time.gov

Steve

Mar 04, 2022

Wow, that is really awesome data. I am interested to know how you collected the data. Did you use instrumentation to get accurate measurements? I usually just look at the time when the second hand crosses a certain position, then quickly look at a digital clock. It is only accurate to about a second or two.

Your numbers are quite impressive. I expect it would drift a bit as the seasons change and the average ambient temperature shifts slightly.

I am starting to run low on the first batch of 100 circuit boards selling on Etsy. My goal is to re-design it slightly for the next batch so a small real time clock can be added. Calibration would no longer be needed. Accuracy would be about a minute per year with a precision RTC.

Steve