What would make a digital watch run fast?

[snowblizz]

So apparently since yesterday (that's when I noticed) my digital clock-radio runs fast. Yesterday I woke at "13:08" and though, "that can't be possible", it wasn't, every other (mechanical) clock and the computers/phone said it was something like 10:40. Befuddled I change the time. This morning again, it thinks it's 11:25 while the rest of the world insists 10:18. What is not normal? Besides my late habits.

It's a 15-20 or so years old Phillips clock radio, connected to the wall socket (and hence always has power, and I know this because if it didn't it'd lose it's time completely) in my apartment and with back-up battery.

At this point my best guess is a localized black hole in my bedroom. Any other ideas? Should I be writing a paradigm shifting physics paper or something?

[factotum]

Does the clock radio have the ability to time sync to a radio time source? If so, it could be interference with that which causes it--my alarm clock occasionally does this.

[snowblizz]

Does the clock radio have the ability to time sync to a radio time source? If so, it could be interference with that which causes it--my alarm clock occasionally does this.

No I honestly doubt that. It never has before. So can't see why it should now. Also, I think it is waaay too old for that to happen.

For the record, it has now advanced 22 minutes in roughly 2,5hrs since I started checking for it around 12:05. A friend suggested some time keeping piece or circuit (??? I don't even know what keeps it on time) has broken. It is positively bizarre!

[Psionic Dog]

Temperature changes can make digital watches run faster or slower, but from personal observations this is rarely more than a few minutes difference over a couple months.

For the clock radio I'll offer the obvious tech answerer of "Unplug it, change the backup battery, then plug it back in." While unlikely one might suppose a low battery was causing unexpected behavior. My next idea is that something inside related to the quartz clock resonator has short circuited, been knocked out of alignment, or otherwise degraded. Has the clock taken a tumble lately? Other than that, no ideas.

[snowblizz]

Temperature changes can make digital watches run faster or slower, but from personal observations this is rarely more than a few minutes difference over a couple months.

For the clock radio I'll offer the obvious tech answerer of "Unplug it, change the backup battery, then plug it back in." While unlikely one might suppose a low battery was causing unexpected behavior. My next idea is that something inside related to the quartz clock resonator has short circuited, been knocked out of alignment, or otherwise degraded. Has the clock taken a tumble lately? Other than that, no ideas.
I actually removed the back-up battery yesterday, so since then it's been running fast without anything "external". And no it hasn't had any external shocks either. It hasn't really been moved around since I moved to my new apartment, oooh 9 months ago soon. So that's unlikely too.

Fun fact, it is an Phillips AJ3150 CLOCK RADIO and you can still download the manual from the Phillip's site. However, aside from being quite fun trivia it doesn't exactly answer the question. Gonna unplug it, resetting the whole thing and see what happens. Just out of curiosity, don't really expect it to help.

The most likely cause at this point I guess is that the tiny machinist running the temporal thingamajig has passed.:smalltongue:
I guess the thing I have most difficulty grasping is that whatever makes it keep time has broken making it go faster rather than slowing or stopping as I'd expect in mechanical clock. It's not like I know a lot of how quartz chips work or if indeed that's how it keeps... kept time.

[Flickerdart]

After 20 years, maybe it's time to accept that it's finally kicked the bucket and get a new one.

[factotum]

I guess the thing I have most difficulty grasping is that whatever makes it keep time has broken making it go faster rather than slowing or stopping as I'd expect in mechanical clock. It's not like I know a lot of how quartz chips work or if indeed that's how it keeps... kept time.

Well, the weird thing is that the actual quartz oscillator that the thing relies upon has a fixed, highly reliable frequency of vibration--that's why they use the things for this! If there's an issue it's somewhere in the attached circuitry, because I don't think you can get the actual quartz crystal to vibrate at a different frequency without changing the local laws of physics. :smallsmile:

[the_david]

I remember a village in the Netherlands having the same problem with clocks when they placed new windmills to generate electricity. That should affect all of your clocks that are plugged in though...

[Maelstrom]

Transformer going bad and affecting the electrical frequency?

[LibraryOgre]

Being chased by a bigger watch.

[snowblizz]

Living in the middle of a city new windmills are somewhat sparse around here. Also, the government is still arguing about financial support for renewable energy so I think most projects are in a holding pattern right now. Admittedly all other clocks I have are either entirely on battery (wall clock) or will adjsut time as needed (phone and computer) so it's hard to say. I rarely get power outages I remember maybe 5 in 15 years living in the city or so.

Frequency issues in the grid was actually suggested by a friend who works within the power transmission industry, (not locally though or he'd be personally suspect...:smallbiggrin:). I'm wondering if it would have any other potential symptoms. The apartment building is new, so one would hope wiring was up to code. Then again they are constantly building in the neighbourhood so I guess stuff could be going on.

Was really odd though, which is why I had to ask. I've never heard of anything like that happening. I mean usually watches are too slow or stop. Although I guess I might have gained a few too many kilos and upset the local gravitational field. Ooooh... great What If for XKCD?:smallwink:


Being chased by a bigger watch.

*Applause* That one almost made my day.

[The Random NPC]

From what I remember form high school physics and reading on Wikipedia, watches use piezoelectric crystals to keep track of time. Those crystals are shaped like a tuning fork, and when electricity is applied to them they vibrate. Another piece of the watch keeps track of the vibrations and decides 1 second has passed when X number of vibrations have happened. I don't know if it vibrates faster if the tuning fork is shorter, but it seems likely to me. Either that or the count got smaller some how. Could also be a temperature thing, but wiki says that makes it go slower.

P.S. Fun fact, you can also vibrate piezoelectric crystals to generate electricity.

[noparlpf]

Well, the weird thing is that the actual quartz oscillator that the thing relies upon has a fixed, highly reliable frequency of vibration--that's why they use the things for this! If there's an issue it's somewhere in the attached circuitry, because I don't think you can get the actual quartz crystal to vibrate at a different frequency without changing the local laws of physics. :smallsmile:

It's possible the crystal got cracked or something, too. That would affect its vibrational properties.


Being chased by a bigger watch.

You win. Best pun I've seen all day.

[BannedInSchool]

P.S. Fun fact, you can also vibrate piezoelectric crystals to generate electricity.
That's also how some otherwise acoustic guitars provide an electric signal. There are crystals in the bridge which are compressed by the vibrating strings, producing a signal similar to the usual magnetic pickups.

So what about the clock? Did running it on battery power slow it down, indicating the power frequency of the grid was off?

[factotum]

It's possible the crystal got cracked or something, too. That would affect its vibrational properties.

Pretty sure the vibration frequency of these things is a function of their crystal structure (e.g. right down at the molecular level) rather than a resonant frequency determined by the crystal itself, so it shouldn't change if they get cracked or otherwise damaged.

[The Random NPC]

Pretty sure the vibration frequency of these things is a function of their crystal structure (e.g. right down at the molecular level) rather than a resonant frequency determined by the crystal itself, so it shouldn't change if they get cracked or otherwise damaged.

Not so, it's based on size, shape, density, and a few other things I'm forgetting.

Found the formula. If there was a crack it would likely change the thickness, which would lead to a different frequency.

f=(1.8752/2pi) * (a/l2) * sqrt(E/12p)

f= fundamental frequency
a= thickness along the direction of motion
l= length of the cantilever
E= Young's Modulus
p= density

[snowblizz]

So what about the clock? Did running it on battery power slow it down, indicating the power frequency of the grid was off?
Oh, I hadn't thought of trying that. Anyway, I'm away from the clock for a few weeks, I'm hoping some "alone time" makes it realise how much it misses me and convinces it to start behaving again.
Shoulda brought it back home-home come to think of it, that would have been another way to test the grid-theory.

[noparlpf]

Pretty sure the vibration frequency of these things is a function of their crystal structure (e.g. right down at the molecular level) rather than a resonant frequency determined by the crystal itself, so it shouldn't change if they get cracked or otherwise damaged.

I'm not sure. But even so, if it's cracked the vibrations might not be transmitted through to the rest of the circuit.