D. I. Y. Watch Timing Machine.

[LittleWatchShop]

A friend of mine assembled this laser setup.  I told him to point it at a watch.  The only thing he had was a quartz clock on the wall.

I need to get him a mechanical watch.  May be the ultimate sensor.

[CWRNH]

4 hours ago, LittleWatchShop said:

A friend of mine assembled this laser setup.  I told him to point it at a watch.  The only thing he had was a quartz clock on the wall.

I need to get him a mechanical watch.  May be the ultimate sensor.

Wow, that's awesome!

[CWRNH]

On 5/22/2021 at 10:37 AM, LittleWatchShop said:

I believe the mystery is solved.  It is a Unijunction transistor (UJT)

They make simple oscillators

Here is one oscillating on my bench.

Thank you

[wlysenko]

I have a new article titled "Calibrating computer sound-system clock with GPS" at wlysenko.blogspot.com. This gives some detail about the GPS calibrator I mentioned previously. I have tried this on six computers. Watch-O-Scope reports daily rates of 2.2, 0.9, 2.1, -3.9, 0.9, and 0.9 s/d for the GPS signal.

 

 

[guidovelasquez]

19 hours ago, wlysenko said:

clock with GPS

Thanks for the document. It is a relatively inexpensive way to calibrate WOS.
I also saw the other articles posted on your blog. My attention was drawn to the article about the degausser.
I would like to invite you to see a post I made on YouTube on the subject. It is an empirical solution, but it works better than ebay degaussing devices.

https://youtu.be/ochzrXkHHF4

 

 

[wlysenko]

50 minutes ago, guidovelasquez said:

I would like to invite you to see a post I made on YouTube on the subject. It is an empirical solution, but it works better than ebay degaussing devices.

https://youtu.be/ochzrXkHHF4

Thanks. These instant demagnetizers, as I call them, are very effective and easy to use. But as some commenter pointed out, a capacitor charged to high voltage can be very dangerous.

And speaking of inexpensive, I found (see my demagnetizer article) that it is possible to build an inexpensive gaussmeter.  A hall sensor costs only about $2.00.

[LittleWatchShop]

2 hours ago, wlysenko said:

a capacitor charged to high voltage can be very dangerous

Indeed...but it is inside of a box.

I am old enough to have grown up with CRT televisions.  Inside that box was some 15-30 thousand volts.  Not a problem.

[guidovelasquez]

5 hours ago, wlysenko said:

inexpensive gaussmeter

Thanks, I'll see the information on the gaussmeter.

 

[Hattori]

On 5/10/2021 at 1:24 AM, wlysenko said:

"The output goes to a 3.5-mm-plug audio cable and is plugged into the line input of the sound card."

I love the idea of GPS time based calibration! 

Could a GPS receiver PPL/SCL signal be connected directly to a piezo element? (so that it could generate audio ticks/pulses loud enough to be detected by a timegrapher microphone) or must there be a driver stage/impedance matching between the PPL output and a piezo element?

 

[praezis]

... if you'd tell us what PPL/SCL is? 

Edited May 26, 2021 by praezis

[Hattori]

Sorry, PPS! (sometimes it is called SCL) time signal on a GPS 

Edited May 26, 2021 by Hattori
clarify

[jdm]

2 hours ago, Hattori said:

I love the idea of GPS time based calibration! 

Precision timing aside, FYI we have a dedicated section where it's considered polite for new members to introduce themselves. 

[JohnR725]

On 5/23/2021 at 1:44 PM, LittleWatchShop said:

May be the ultimate sensor

maybe we should just hack an optical microphone? or even better yet hack a fiber optic microphone. the fiber optics is nice because you can run the optical source from somewhere else you don't have to have the laser there or whatever the light sources.

[wlysenko]

4 hours ago, Hattori said:

Could a GPS receiver PPL/SCL signal be connected directly to a piezo element? (so that it could generate audio ticks/pulses loud enough to be detected by a timegrapher microphone) or must there be a driver stage/impedance matching between the PPL output and a piezo element?

I think you are asking about using GPS on a stand-alone timing system, not a computer-based system like Watch-O-Scope.  I have done something similar to check the clock in a computer (a Sony) that did not have any audio input jacks but did have a built-in microphone. I connected the GPS PPS signal to the  line input of my usual computer and turned on the speakers. Now I could hear the PPS "ticks."  I placed the Sony computer, running the Watch-O-Scope software connected to the built-in microphone, near a speaker and did the timing. It worked. I don't know if the piezo element of your machine would pick up sounds in the air but it is worth trying. Turn up the volume and bring the mic close to the speaker. You may have to reduce the duty factor of the PPS signal (10% by default) to make this work because both the rising and falling edges produce a tick.

[Hattori]

Wlysenko, I am only looking for an easy way to calibrate the sound-card clock. Just like you do. BUT I cannot use a line input into the sound card. So I am just trying to figure out if the PPS signal can be output into a simple transducer, like a piezo element? That transducer is then placed on the timegrapher microphone and Watch-O-Scope can be calibrated using the PPS pulses, rather than using less precise ticks from a quartz watch.

Edited May 26, 2021 by Hattori

[JohnR725]

2 minutes ago, Hattori said:

easy way to calibrate the sound-card clock

what about an analog quartz watch that stepping once per second? It's small portable and it's making clicking sounds each time it steps.

[Hattori]

I have used an analog quartz watch to calibrate but a GPS time based device is so much cooler  and precise..

 

[JohnR725]

4 minutes ago, Hattori said:

and precise.

what about witschi's concerned that you should be using a GPS specifically used for timing purposes?

15 minutes ago, Hattori said:

piezo element

rather than a piezo what about a small magnetic speaker? Magnetic speakers have coils and more mass than a disk. Because for calibration we probably don't care but for an actual watch pickup were supposed be picking up a vibration not an audio sound. So I don't know how much vibrating a disk does versus a moving coil.

[wlysenko]

2 hours ago, Hattori said:

Wlysenko, I am only looking for an easy way to calibrate the sound-card clock. Just like you do. BUT I cannot use a line input into the sound card

Okay, here is what you want, I think. I fed the PPS output of the GPS receiver/antenna module (that would normally go to the line input in my normal  operation) into a piezo disk. I think it is the same kind of disk I used when I made my WOS microphone. The output is very faint. I can hardly hear it. I placed this output piezo touching the WOS mic piezo as seen in the photo.

Then I ran the WOS mic into my WOS preamp, which was fed into the audio interface line input (exactly as I normally do). Here is what it looks like on the WOS scope view.

The GPS PPS is set to 5 Hz and 10% duty factor. The WOS software gives me my usual daily rate of +2.2 s/d.

 

[Hattori]

Wow! That is exactly what I am looking for! Thank you so much for testing this!

So maybe there needs to be a small amplification stage between the PPS signal and the transducer.  Good to know.

I wonder why the piezo creates two peaks from the square wave? The graph looks almost like one from a mechanical watch. And your timing result seems to be quite similar to the result from the other day. 

I ordered a GPS yesterday so I will soon be testing this.

"The GPS PPS is set to 5 Hz and 10% duty factor" What does Duty Factor mean?

Edited May 27, 2021 by Hattori

[Hattori]

11 hours ago, JohnR725 said:

what about witschi's concerned that you should be using a GPS specifically used for timing purposes?

rather than a piezo what about a small magnetic speaker? 

Are you wondering if I will loose sleep if Witschi gets to sell one less £1.595 GPS receiver/antenna? Hmmm, let me get back on that one..

Thanks to wlysenko's test proving that a piezo transducer connected to the PPS can give an output loud enough to trigger the WOS, a simple earbud may be even better suited as a transducer thanks to lower impedance that may result in a higher output? I will give that a try before adding a simple amplification stage - as soon as I receive my £8.83 GPS receiver/antenna.

Edited May 27, 2021 by Hattori

[JohnR725]

3 minutes ago, Hattori said:

Are you wondering if I will loose sleep if Witschi gets to sell one less £1.595 GPS receiver/antenna? Hmmm, let me get back on that one..

actually I was concerned about whether you'd be upset that? You going to go to all the trouble to calibrate your timing machine yet you're shortchanging yourself on a substandard GPS receiver.

What which she is recommending is a specific GPS for timing. So they claim a normal GPS is only good for 0.01-0.001 seconds.  whereas their GPS receiver claims to be Achieved tolerance of 1 PPS= +/- 15 - 75 ns (nano seconds), related to the atomic clock of the GPS system. = 0.015 – 0.075 milliseconds.  So how much sleep will either one of us have lost being concerned over the inaccuracy of a common GPS?

 

[Hattori]

I did note their claim on the accuracy of their GPS receiver. I guess they use it to motivate the very high price of their GPS. 

Meanwhile I will sleep even better knowing I saved £1.585 by going for only 0.01-0.001 seconds accuracy  

 

 

 

[JohnR725]

8 minutes ago, Hattori said:

I did note their claim on the accuracy of their GPS receiver. I guess they use it to motivate the very high price of their GPS. 

what's interesting about their pricing is that it's an old GPS providing I'm reading the specs correctly. There is a link below to a timing GPS. If you look on eBay the Chinese have a circuit board with either the 8T or the cheaper older 6T version. But it does look like the 8T beats out witschi for specifications and price looks quite reasonable unfortunately doesn't have the antenna so you have to get that. Plus doesn't look like there's any specifications for the board minor challenge.

 

https://www.u-blox.com/en/product/neolea-m8t-series

 

[Hattori]

I ordered this one from their Polish warehouse, yesterday. : https://www.aliexpress.com/item/4001316189127.html 

fully aware there may not be a PPS socket on the board inside it (since it has the USB interface) BUT I like the fact that you get a M8030-KT GPS, an antenna, a housing and a "PSU" and I will try to find the PPS trace from the chip on the circuit board and solder a cable to it. Or just take the output voltage that lights up the "Syncro" 1 s blinking LED. I am just not sure if it has the same high accuracy as the PPS signal?

Should that not work I also ordered this:

GY-NEO6MV2 GPS Module Aircraft Flight Controller APM 2.5 TE518+ Flugregler | eBay

so that I will be sure to get the PPS signal.

 

Edited May 27, 2021 by Hattori