1. Do quartz watches commonly have an adjustment for regulating them?
2. How can I pick up the signal from the quartz oscillator and count it?

So far I've been unable to pick up a signal with a simple loop. I assume
such a signal is at 32,768 Hz, and that it must be amplified to drive a
counter. The trouble I see, is that one Hz error at this frequency
corresponds to a significant error over time.

Fred

"Fred McKenzie" wrote in message
...
1. Do quartz watches commonly have an adjustment for regulating them?
2. How can I pick up the signal from the quartz oscillator and count it?

So far I've been unable to pick up a signal with a simple loop. I assume
such a signal is at 32,768 Hz, and that it must be amplified to drive a
counter. The trouble I see, is that one Hz error at this frequency
corresponds to a significant error over time.

Fred
they used to have a an adjustment but that's seems to be missing on all the
recent ones I have put batteries in

I'm on my 3rd Casio TeleMemo 150 in 10 years; newest one about a year
old. All have differed in tiny construction details inside, but all
have had a trimmer capacitor for regulating. As have all the Casio
watches belonging to others in which I've changed batteries. The
trimmer is marked with a screwdriver blade symbol on the CRS shield.
Although there is surely a test point to access the oscillator, I've
adjusted mine by trial and error to about 1 second/month. In the
TeleMemo 150, counterclockwise on the trimmer seems to be frequency
increase.

Fred McKenzie ) writes:
1. Do quartz watches commonly have an adjustment for regulating them?
2. How can I pick up the signal from the quartz oscillator and count it?

So far I've been unable to pick up a signal with a simple loop. I assume
such a signal is at 32,768 Hz, and that it must be amplified to drive a
counter. The trouble I see, is that one Hz error at this frequency
corresponds to a significant error over time.

Fred

If you aren't coupling the signal properly, you won't get a good reading.
I've seen suggestions of getting the signal off the LCD backplane, which
is accessible and probably would work so long as it derives from the crystal
oscillator.

But what were you using for a frequency counter? Unless there is syncing
to the input signal, there will always be a plus or minus 1 on the least
significant digit, because there's no way of ensuring that the timing
gate in the counter will always fall on the same point of the waveform.

Measuring 10MHz, 1Hz is a small percentage of the total frequency, but
as you go lower in frequency the error becomes more significant. You
can increase the gate time, so you can get the .1Hz reading or even .01Hz
reading, which then makes the least significant digit 1/10th or 1/100th
of what it is previously, and thus making the plus or minus 1 error
less significant at 32KHz. But, increasing the gate time means it
takes more time to do the count, so you have to keep things steady for
longer (and with a noisy signal, the affect of the noise may increase
the count error).

Often when measuring low frequencies, they shift things around and
the counter becomes a period counter. Here the input signal becomes
the gate signal, and it is counting a much higher frequency. That
gives the period of the unknown signal, and all you have to do is
mathematically invert the number on the readout. But I'm not sure
how common the period function is on most frequency counters today,
and it would require modification to turn a counter into a period
meter.

Michael

In article ,
(Fred McKenzie) wrote:

1. Do quartz watches commonly have an adjustment for regulating them?

Some of them have a small "trimmer"; some do not.

2. How can I pick up the signal from the quartz oscillator and count it?

So far I've been unable to pick up a signal with a simple loop. I assume
such a signal is at 32,768 Hz, and that it must be amplified to drive a
counter. The trouble I see, is that one Hz error at this frequency
corresponds to a significant error over time.

You're very unlikely to be able to use any kind of frequency counter to
measure the oscillator with sufficient accuracy. There are close to a
hundred thousand seconds in a day. Measuring to one part in 10^5 will
leave you with an error of half a minute a month; not very good at all
for a timepiece these days.

Just compare the long-term rate of the watch with a good network time
server or WWV, and make slight adjustments every week or so until you
get things dialled in. By going to longer and longer "integration
periods" you can approach any desired accuracy. That method has the
advantage of not intruding on the normal operation of the oscillator in
even a slight way. And yes, it matters, especially for those
low-frequency "tuning fork" cut crystals.

Then you'll find out that those watch oscillators are just not that
stable to begin with. Temperature and even orientation effects will
become obvious, as will drift due to voltage change. Not only is the
crystal warmer when it's on your wrist, but so is the rest of the
circuitry. That will change the gain of the oscillator, and so affect
the frequency. Most of those oscillators depend upon the (relatively)
stable temperature of your wrist for decent performance, so be sure to
wear the timepiece for your "normal" number of hours each day while
you're "calibrating" it, or you won't get it right, long term.

Isaac

In article , Isaac
Wingfield wrote:

You're very unlikely to be able to use any kind of frequency counter to
measure the oscillator with sufficient accuracy. There are close to a
hundred thousand seconds in a day. Measuring to one part in 10^5 will
leave you with an error of half a minute a month; not very good at all
for a timepiece these days.

I appreciate the comments. Now all I need to do is to look inside and see
if there is a trimmer. I can see where the slightest error would
accumulate over time.

I have an old Fluke counter (7220) with a low-frequency option. It
phase-locks a higher-frequency oscillator with the input signal, counts
the oscillator and displays it as the lower frequency. It would be worth
a try if I could pick up a strong enough signal from the watch without
warping it.

Fred

You run the risk of loading down the circuitry.

You might try using a sensitive AM shortwave receiver to detect a
harmonic of the oscillator. Use an unductive coil around the timepiece.
Then using a signal generator with a very precise reference oscillator
as a BFO, warp the crystal oscillator for a zero beat. If you are at the
9th harmonic (for example) you will improve your accuracy 9 times. Use
WWV to verify your signal generator is accurate as a first step.

Also don't discount the temperature variations of wearing it for 12
hours and then leaving at room temperature for 12 hours. You might find
you have made things worse by adjusting it at room temperature.

Joe

Fred McKenzie wrote:

In article , Isaac
Wingfield wrote:



You're very unlikely to be able to use any kind of frequency counter to
measure the oscillator with sufficient accuracy. There are close to a
hundred thousand seconds in a day. Measuring to one part in 10^5 will
leave you with an error of half a minute a month; not very good at all
for a timepiece these days.



I appreciate the comments. Now all I need to do is to look inside and see
if there is a trimmer. I can see where the slightest error would
accumulate over time.

I have an old Fluke counter (7220) with a low-frequency option. It
phase-locks a higher-frequency oscillator with the input signal, counts
the oscillator and displays it as the lower frequency. It would be worth
a try if I could pick up a strong enough signal from the watch without
warping it.

Fred



--
Joe Leikhim K4SAT
"The RFI-EMI-GUY"

"Follow The Money"

You run the risk of loading down the circuitry.

You might try using a sensitive AM shortwave receiver to detect a
harmonic of the oscillator. Use an inductive coil around the timepiece.
Then using a signal generator with a very precise reference oscillator
as a BFO, warp the crystal oscillator for a zero beat. If you are at the
9th harmonic (for example) you will improve your accuracy 9 times. Use
WWV to verify your signal generator is accurate as a first step.

Also don't discount the temperature variations of wearing it for 12
hours and then leaving at room temperature for 12 hours. You might find
you have made things worse by adjusting it at room temperature.

Joe

Fred McKenzie wrote:

In article , Isaac
Wingfield wrote:



You're very unlikely to be able to use any kind of frequency counter to
measure the oscillator with sufficient accuracy. There are close to a
hundred thousand seconds in a day. Measuring to one part in 10^5 will
leave you with an error of half a minute a month; not very good at all
for a timepiece these days.



I appreciate the comments. Now all I need to do is to look inside and see
if there is a trimmer. I can see where the slightest error would
accumulate over time.

I have an old Fluke counter (7220) with a low-frequency option. It
phase-locks a higher-frequency oscillator with the input signal, counts
the oscillator and displays it as the lower frequency. It would be worth
a try if I could pick up a strong enough signal from the watch without
warping it.

Fred



--
Joe Leikhim K4SAT
"The RFI-EMI-GUY"

"Follow The Money"