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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

Feb 13

Steve using the black and yellow shield V4 would you still need to short the two pins on the DS3231.

Steve

Feb 13

Replying to

Yes. That edit is needed for the real time clock to work.

normhuntley

Feb 12

Steve: I have the black and yellow CNC shield V4 would the driver code have to be changed to run the clock.

Steve

Feb 13

Replying to

The same edits should still work. The edit to connect the jumpers to Vcc could be optional, but it is probably easier to just do all of them.

normhuntley

Feb 13

Replying to

I am going to print a new clock and use it. The clock with the original board is running very well in three weeks we have got it down to about 3 seconds slow it is very quiet since we printed the hub gear in TPU you could sleep with it in the room no problems.

normhuntley

Jan 31

The silent clock with the original controller and a TPU hub gear you cannot hear anything.

normhuntley

Jan 31

If you want the silent clock to be silent, make the hub gear out of TPU what a difference it is suuuuuper quiet.

Steve

Jan 31

Replying to

Great idea.

normhuntley

Jan 29

Steve: I downloaded what I thought by the description was the Silent Clock with the new base for the CNC shield V4 but it was not. thanks Norm

normhuntley

Jan 29

Replying to

Steve: All the object parts are for the original motor controller clock. I don't see anything for the V4 shield clock.

Steve

Jan 29

Replying to

They need to be downloaded individually under Object Parts. There are 6 or 7 new files.

normhuntley

Jan 29

Replying to

We found them

normhuntley

Jan 28

Steve: I printed gear 1 and 2 at 100.5% they mesh better and the clock is quieter. Working good.

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.

Steve

Jan 28

Replying to

Hi Norm,

There are 8 clock designs released and some of them have multiple configurations. The stepper motor clock was just updated with a second controller based on the CNC Shield V4. I was trying to guess some reasons that the new controller might keep accurate time but be jerky and noisy. Then I realized that you recently ordered the custom resistor based controller. It often helps to specify which configuration you are building. It may also help others that search for similar issues in the future.

The most likely causes of jerkiness in the resistor based controller are resistors inserted in the wrong order, cold solder joints, or the stepper motor wires in the wrong order.

The easiest first test is to swap the middle two stepper motor wires at the terminal block. The order needs to be A+, A-, B+, and B-. The motor still rotates, but in a very jerky motion if the wires are A+, B+, A-, B-.

If that doesn't work, then try checking the 16 resistors. The algorithm approximates a sine wave current using binary weighted resistor values. Any missing or wrong value resistors will produce a distorted (and possibly non-monotonic) sine wave. The results are also a jerky motion.

If these hints don't help fix the issue, then a video can sometimes help.

Steve

normhuntley

Jan 28

Replying to

Checked all resistors they are correct changed the two center wires that smoothed it out has some noise but that is between gear 1 and gear 2.

normhuntley

Jan 28

Replying to

The clearance between gear 1 and gear 2 is a little excessive I need to figure out how to close it up I believe that will cut down on the noise. The stepper motor is pretty quiet by itself.

normhuntley

Jan 21