Ulrich,

Yes, this works well, for both those with seconds hands (one magnetic pulse per second) and those with only minute/hour hands (one or two steps per minute). A large coil of wire is all you need. Have a look at the watch timing tools and sensors at http://www.bmumford.com/microset.html or http://www.bmumford.com/mset/modelwatch1.html

Here's an example using a magnetic sensor: http://leapsecond.com/pages/Junghans/

/tvb

In message 94A06362A4E942EE9EC49A685C099C32@athlon, "Ulrich Bangert" writes:

Yes.

And then I threw my wrist watch away, having documented how shit it was :-)

If your smartphone has a magnetometer, you can measure it that way, but you
have to get pretty close to the chip in the smartphone.

--
Poul-Henning Kamp      | UNIX since Zilog Zeus 3.20
phk@FreeBSD.ORG        | TCP/IP since RFC 956
FreeBSD committer      | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.

In the United States we can buy analog quarts watches from Wal-Mart for
under 15 dollars.  When the battery dies you don't even bother to replace it
you just buy a new watch, unless...the one you have is very good.  There is
a lot of variation and buying one is the luck of the draw.  They can be as
bad as 1 minute a month and they always seem to be gaining.  Right now I
have one that gains about 2 seconds a month.  I fully intend to see if it is
possible to replace the battery when it runs down.  Counting motor pulses
seems to be a little impractical because it would take 12 days to get to 1e6
accuracy.

Regards.

Max.  K 4 O DS.

Email: max@maxsmusicplace.com

Transistor site http://www.funwithtransistors.net
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----- Original Message -----
From: "Tom Van Baak" tvb@LeapSecond.com
To: "Discussion of precise time and frequency measurement"
time-nuts@febo.com
Sent: Tuesday, April 15, 2014 8:52 AM
Subject: Re: [time-nuts] Measuring the accurcy of a wrist watch

This email is free from viruses and malware because avast! Antivirus protection is active.
http://www.avast.com

You don't count the pulses, you measure the separation between the pulses.
Just like with the 1PPS output on your C-Beam.

-Chuck Harris

Max Robinson wrote:

Here is a discussion forum page that shows a commercial quartz watch
timing machine in use:
http://omegaforums.net/threads/quartz-watches-some-information-some-may-find-interesting.5475/

The machine obviously measures the time of each second "tick", either
electrically or acoustically, because it can tell you the instantaneous
rate over one second based on the time between ticks. In the example
shown, the crystal is fast by 4.18 seconds/day (48 PPM) based on the
period between most ticks, but every 60th tick has a longer period due
to inhibition (oscillator pulse dropping), and the net rate measured
over 60 seconds is 0.32 seconds/day (3.7 PPM).

There is a bunch of additional information about the motor drive pulses
too.  The article explains what it means in some detail.

It seems to me that calculating the rate information should require
nothing more than capturing the leading edge of each motor pulse and
time stamping it, at a rate of 1 data point per second.  The motor
information requires capturing several pulses (at a rate of a few kHz
max.) every second.

• Dave

On 15/04/2014 09:52, Tom Van Baak wrote:

Tom,

can you explain what exactly you understand by "a large coil of wire"?

Did you make the easurements on the Junghans with a DIY sensor or with one
of the commercially available?

I have made some basic tests with a coil coming from a loudspeaker's cross
over network. It has a few hundred windings, R=1.3 Ohms, 2.3 mH, but the
only thing i receive with this coil is a strong 10 Mhz signal...perhaps no
real surprise in a time nuts laboratory.

Best regards

Ulrich

Sorry, by large I meant a large number of turns; the coil itself is quite small. Rather the winding one myself I just used the pickup coil from an old cheap plastic self-impulsed pendulum clock. The wire is extremely fine and there must be thousands of turns since the spool diameter is only 15-20mm and the net resistance is 3.5k. Here are some iPhone photos I just took:

http://leapsecond.com/pages/Junghans/coil.htm

Both. The commercial ones sold by Bryan Mumford are excellent; his instrument includes signal conditioning, adjustable high gain, and other useful features. It's meant for watchmaker types with no electronics background. It works perfectly out of the box.

The Junghans wristwatch is extremely well engineered for long-life and the leaked magnetic signal is the weakest of any watch I've measured. Still, it can be measured. The placement of the pickup coil on the watch face needs to be optimized for best "reception", or any reception at all for that matter.

By contrast, a typical AAA-battery desk/wall quartz clock movement generates a huge magnetic signal. It is so clean that you can clearly see both the start (+) of the impulse and the end (-) of the impulse about 30 ms later. In fact I suspect it's actually 31.25 ms, or 1/32 s, since that's 1024 cycles of a 32.768 kHz oscillator. See:

sensor placement:
http://leapsecond.com/pages/Junghans/quartz-clock.jpg
output to scope:
http://leapsecond.com/pages/Junghans/coil-aa.gif

I suspect your 1.3 ohms means the number of turns is far too low.
I don't see any RF here, nor even very much 50/60 Hz.

/tvb

The first sensor I'd think of if I wanted to measure a wrist watch would be
a microphone.  Listen for the tick.  You'd need a good quality
preamplifier.  Place the watch directly on top of the microphone then the
mic in a closet with a blanket  on it.

Good quality studio microphones are very, very sensitive.  At home with two
doors shut my condenser mic picks of the motor in the fridge, wall clock
ticks and the nearly silent fan motor in computer 20 feet away.    Then in
post processing software I can find and identify the frequency components
of each of those the remove most of the signal.  I'm not by any means an
audio pro and I'm using entry level recording gear.  I'm making digital
recording but for precision timing you'd need to use the analog signal
after a pre-amplifier and apply a sharp bandpass analog filter.

About using a coil, I'd assume they use one with many thousands of turns,
maybe 100x more then a crossover coil.  and place the watch, coil and
signal conditioning amplifier all in a faraday shield and apply a powerful
analog filter.  But even if this works it needs a battery powered watch,
it couldn't pick up a purely mechanical movement.

I was all set to

On Wed, Apr 16, 2014 at 6:21 AM, Ulrich Bangert df6jb@ulrich-bangert.dewrote:

--

Chris Albertson
Redondo Beach, California

It does not take a large pickup coil to pick up the magnetic field of a
quartz watch movement tick.

Radio Shack used to sell suction cup "telephone pick up coils" but I doubt
they have them anymore. These piggybacked on a phone receiver. They are
still out there,
http://www.elliottelectronicsupply.com/camera-security-equipment/listening/telephone-pickup-coil-suction-cup.html

Just as effective is any unshielded mH-range inductor. e.g.
http://www.mouser.com/ProductDetail/Murata-Power-Solutions/13R336C/?qs=gLyyx31KZaCXYrPIar3DqA==

I work with e.g. Rick Campbell's R2 series receivers, which do AF filtering
using inductors and these pick up the tick, tick, tick from my watch clear
as day from over a foot away. Back when I had a CRT computer monitor on my
desk, they picked up the flyback and deflection frequencies real well.

Tim.

On Wed, Apr 16, 2014 at 1:51 PM, Chris Albertson
albertson.chris@gmail.comwrote:

I just did an experiment.  Place a simple quartz movement wrist watch on
top of a Fender Stratocaster guitar.  I get a very strong and easy to
detect signal.  A loud and sharpt "ping" once per second.  More then 1 volt
peak to peak.  I can cancel almost all the background hum and hiss in the
normal way by using the selector switch on the guitar.

The guitar has a pickup coil with many thousands of turns of #40 wire.
With the selector with at #2 position there is a second coil some inches
away that is wound in the opposite direction and the two are added
canceling any field that is filing the room.

I tried the same with a wall clock and all I had to do was hold the clock
an inch away.  The wrist watch was placed on top of the strings a few mm
above the bridge PU.

These is likely about 3 oz of #40 magnet wire on a guitar PU.  If I were
building a sensor I'd do it just like the guitar.  one coil to pick up the
signal and another identical coil some inches away to to pick up ambient
"noise" and then wire the two in parallel but in anti-phase.

If yu happen to have a guitar around, you have a watch sensor.

On Wed, Apr 16, 2014 at 10:43 AM, Tom Van Baak tvb@leapsecond.com wrote:

--

Chris Albertson
Redondo Beach, California

Chris,

I do not own a guitar with single coil pickups but I will surely give it a
try to find out whether the humbuckers of my Gibson Firebird & SG Standard
will also do the trick!

Best regards

Ulrich

Tom,

many thanks for your help. Will give it a new try over Eastern!

Best regards

Something to consider is that most pickups are biased with a fairly strong
magnetic field.

Don't know if this would cause any damage or changes in operation of a
mechanical watch but something to consider...

http://www.guitarnuts.com/wiring/pickups.php

Dave

Hello,

I've seen that on a forum (in french sorry) :
http://www.forum-mdp.com/t16731-un-chronocomparateur-pour-petit-budget

It's an application for iPhone called "Kello", look at the picture and you will understand. The most difficult part seems to find the right position of the microphone.

Claude

On Thursday, 17 April 2014, 19:55, DaveH info@blackmountainforge.com wrote:

Something to consider is that most pickups are biased with a fairly strong
magnetic field.

Don't know if this would cause any damage or changes in operation of a
mechanical watch but something to consider...

http://www.guitarnuts.com/wiring/pickups.php

Dave

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Are watches damaged by magnets?  I hope not because magnets are common.
Yes a guitar does have some powerful Alnico magnets in the coil.

If this were a problem I think we would have heard about it.  My guess is
that watch parts are non-magnets brass and stainless and glass and so on.
Not plain steel or iron.  But maybe there are cheap watches made with
stamped steel part?  I don't know.

In any case my experiment of placing the watch nest to the pickup caused no
damage.  Next time I get a chance I'll haul the guitar over to the HP
counter and see if I can't measure the watch tick period.

Something to consider is that most pickups are biased with a fairly strong

--

Chris Albertson
Redondo Beach, California

I remember growing up (50 years ago) that the good watches were marked as
being non-magnetic.  I would guess that this is standard now.

My concern is that the moving balance wheel could have an eddy current
induced into it and the resulting magnetic field might cause it to slow
down.

http://en.wikipedia.org/wiki/Balance_wheel

http://en.wikipedia.org/wiki/Eddy_current

The act of measurement should not cause a change in what you are measuring.

Dave

Yes, magnetic fields mess up mechanical watches.  My dad was a watchmaker and found the need to demagnetize all the watches he worked on.  The hairspring was the  most sensitive part, and the coils would stick together if magnetized, and the watch would run very fast.

Bob

On Thursday, April 17, 2014 9:06 PM, DaveH info@blackmountainforge.com wrote:

I remember growing up (50 years ago) that the good watches were marked as
being non-magnetic.  I would guess that this is standard now.

My concern is that the moving balance wheel could have an eddy current
induced into it and the resulting magnetic field might cause it to slow
down.

http://en.wikipedia.org/wiki/Balance_wheel

http://en.wikipedia.org/wiki/Eddy_current

The act of measurement should not cause a change in what you are measuring.

Dave

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and follow the instructions there.

Early watches were more susceptible to magnetic influence than
were later... this is primarily because the early watches used
high carbon steel hairsprings for the balance wheel, and when
they got magnetized, the spring coils would stick together...

Later watches used elinvar for the hairspring coils because its
spring constants were less affected by temperature variations...
a nice side benefit is it is not easily magnetized.

However, when an elinvar hairspring gets magnetized, it is very
difficult to demagnetize it using conventional means.

Demagnetizers work by rapidly alternating the polarity of the
magnetic field, and slowly decreasing the strength of the field.
This causes the magnetic poles of the ferrous atoms to get randomly
aligned, which is the demagnetized state... But if the item that
is magnetized is so light weight and flexible that it can move
with the field, it won't get demagnetized... which is what happens
with the hairspring.  The only way I know to demagnetize a hairspring
of this sort is to immobilize the spring with wax, and then run it
through the demagnetizer... then melt the wax, and clean the spring
with naptha.

Fun times!

-Chuck Harris

DaveH wrote: