Digital Clock Speeding Up (ie Gaining Time)

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Hi guys.

I had a typical digital alarm clock for a few years.  I noticed it
started to report the time a few minutes fast.  If I reset it the time
would still go forward.

I'm estimating it gains around a minute a week.  This doesn't sound
like much, but in 6 months the clock is half an hour ahead of the
correct time.

I thought the clock might be playing up because it is plugged in with a
dozen other electrical devices (computer, home theatre etc).  To
confirm I plugged it into another socket on it's own in another room.
The problem persisted so I threw it out.

I got a new clock, and after a few months it is 20 mins ahead!

Does anybody know the cause of this problem?

Thanx 4 looking.


Re: Digital Clock Speeding Up (ie Gaining Time)


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Most mains powered clocks derive their time form the 50Hz mains which
is very accurate over a long time period. So your clocks are most
likely picking up noise on the mains that is causing missing pulses or
some such problem. Try adding a good mains filter to the clock, or just
get a clock that does not rely on the 50Hz mains (usually the battery
powered type).

Dave :)


Re: Digital Clock Speeding Up (ie Gaining Time)



"David L. Jones"  wrote


Most mains powered clocks derive their time form the 50Hz mains which
is very accurate over a long time period. So your clocks are most
likely picking up noise on the mains that is causing missing pulses or
some such problem.


****What???
The clock is supposedly gaining time,not losing it!
If it is missing "pulses" it will lose time!

Brian Goldsmith

Re: Digital Clock Speeding Up (ie Gaining Time)


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Oops, I meant "extra" pulses.

Dave :)


Re: Digital Clock Speeding Up (ie Gaining Time)






**  Groper Alert  !

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**  Likely the clock is not being powered by the AC mains supply on a 24 / 7
basis.

During the unpowered periods, the internal ( battery powered) time base
oscillator takes over -  and it runs a tad fast.

Maybe the missus uses it power outlet for her vacuum cleaner or her steam
iron or her  ............




.......    Phil





Re: Digital Clock Speeding Up (ie Gaining Time)


On 17 Oct 2006 01:12:55 -0700, snipped-for-privacy@mail.tpg.com.au put finger
to keyboard and composed:

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There was a clock that featured in a thread at sci.electronics.repair
some years ago that was affected by off-peak pulses or "remote-reading
electrical power meters" or similar signals.

http://groups.google.com/group/sci.electronics.repair/msg/159076a073f7a83e?hl=en &

- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.

Re: Digital Clock Speeding Up (ie Gaining Time)


Thanx 2 everyone who replied.

When you say battery powered clocks, do you mean regular alkaline
batteries?  If so, wouldn't battery powered clocks lose time when the
battery goes flat?  And, wouldn't they go flat often?

I don't think my clock has a battery at all.  Whenever power is lost
the clock is reset to 12:00.

I noticed the clock on my microwave keeps the right time.  Does that
sound right if there is a problem with the power here?

Is this the type of filter I should be looking at getting?
http://www.dse.com.au/cgi-bin/dse.filereader?45362276029a446c2741c0a87f9c06f4+EN/catalogs/CTG0001024


Re: Digital Clock Speeding Up (ie Gaining Time)




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**  No one mentioned  *any* such thing.

  You asinine Google Groups  WANKER   !!





...... .  Phil




Re: Digital Clock Speeding Up (ie Gaining Time)


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I mentioned it Phil, in my first post.
 
Dave :)


Re: Digital Clock Speeding Up (ie Gaining Time)


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No, an LCD display clock should last for years, just like a digtial
watch.
Something like this:
http://www.dse.com.au/cgi-bin/dse.storefront/45369dd009708ca0273fc0a87f9c074e/Product/View/Y0621

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That means it most likely has better designed circuitry (filtering)
that gets pulses from the 50Hz mains. With your other clocks you have
just been unlucky with a poorly designed product - twice.

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http://www.dse.com.au/cgi-bin/dse.filereader?45362276029a446c2741c0a87f9c06f4+EN/catalogs/CTG0001024

None of them seem to have the word "filter" in them, just "surge
protection", that is different. Not that a filter is guaranteed to work
anyway, cheaper to simply buy an LCD digital clock.

Dave :)


Re: Digital Clock Speeding Up (ie Gaining Time)


Thanx 4 your help Dave.

I'll get myself an LCD clock.

David L. Jones wrote:
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http://www.dse.com.au/cgi-bin/dse.storefront/45369dd009708ca0273fc0a87f9c074e/Product/View/Y0621
Quoted text here. Click to load it
http://www.dse.com.au/cgi-bin/dse.filereader?45362276029a446c2741c0a87f9c06f4+EN/catalogs/CTG0001024
Quoted text here. Click to load it


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