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My AC digital clocks run fast. Cheap fix?

Discussion in 'Electrical Engineering' started by Peter, Nov 15, 2009.

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  1. Peter

    Peter Guest

    I can't seem to get my local power company interested, but I suspect they are
    the cause of the problem. I've got numerous AC powered digital clocks in VCRs,
    DVRs, microwave ovens and clock-radios. The appliances are all made by
    different manufacturers. Some were purchased this year and some are more than
    10 years old. All run fast, several seconds/day. I have no problems with
    brownouts, flickering lights, etc. I use only typical home appliances and most
    of them were used in my previous homes (in other cities) where the older digital
    clocks that are now running fast kept almost perfect time.

    Doing a little research on the web, I found an article "Solving the Fast Clock
    Problem" which can be viewed at this link:
    http://www.writenowcommunication.com/PDF_Files/Solutns/Sol03.pdf

    This article leads me to believe that my problem is external to my home. I do
    not own an oscilloscope or any other sophisticated electrical analysis equipment
    and I don't want to spend the money to hire an electrical engineer to assess the
    quality of the power being supplied to my home. All the "power conditioners"
    I've explored seem quite expensive.

    Some of the clocks that are running fast are plugged into surge strips that have
    EMI/RFI suppression built-in, so I doubt that an additonal EMI/RFI filter would
    solve my problem.

    Is there a simple, inexpensive solution to my problem or am I condemned to
    resetting about 7 digital clocks each week if I want my wake up when I want to
    and record TV programs when they are broadcast rather than before they start and
    miss the endings?
     
  2. Bill

    Bill Guest

    The electric company is supposed to closely regulate the "60 cycles" so all
    those clocks will keep perfect time.

    Complain to your state agency which regulates your electric company. Might
    also call a TV station or two and a newspaper. Before doing that, find other
    people in your area who have the same problem...



    "Peter" wrote in message
     
  3. Rich.

    Rich. Guest

    Although it is easy to blame the power company, I would have to say it is
    not their fault or problem. The business of the power company is just that,
    to supply you with power. Nothing within providing that service indicates
    they're responsible to provide a clock timing pulse. This business of clocks
    being accurate falls back to the manufactures. It's up to them to make a
    product that works correctly. Instead of building an accurate clock, they've
    taken the cheaper shortcut of trying to use the 60 Hz power line as the
    timing circuit.
     
  4. Rich.

    Rich. Guest

    The problem has nothing to do with the 60 Hz sine wave. This problem is
    caused by additional spikes on the power lines.
     
  5. krw

    krw Guest

    There are requirements for long-term (30-day) accuracy.
     
  6. Here, in Crete, south Greece, the local control centre of the utility
    (www.dei.gr) has a special display on the control room, that tells how
    accurate a 50 Hz clock would be, had it followed the mains frequency. So.
    yes, utilities care for those clocks, at least in Greece.
     
  7. James Sweet

    James Sweet Guest


    The line frequency should have excellent long term accuracy. It may
    drift a bit during the day but should catch up at night. If you're in
    the US, I don't see how the frequency could be off since it's one big
    interconnected grid. You might have noise on the line causing this. Can
    you tell if the clocks drift steadily and in sync with one another or do
    they sporadically skip?
     
  8. Peter

    Peter Guest

    They drift steadily. I haven't actually taken the time to precisely measure the
    amount of drift that each clock has, but after a week, each is about 9-12
    seconds fast. (My calibration standard is the time on both my "atomic" desk
    clock and wrist watch, which are never more than an infinitesimal amount
    different from each other.) It's a real pain for my VCRs and DVRs when we are
    out of town for several weeks. Inevitably we end up missing the end of programs
    we recorded near the end of our absence. Lately I've been adding 1-2 minutes to
    the turn-off time to avoid that.

    From the responses so far, sounds as though I'm going to have to live with this
    issue until I move. I'll check with some of my neighbors to see if they have
    noticed the same problem. However, I suspect from the random pattern with which
    they collect their newspapers off their lawns that they may be less compulsive
    than I am and not even be aware of the problem if they have it. If they have
    cable or FIOS TV service (I don't bother) their VCRs and DVRs probably remain
    accurate from the time signal I believe is transmitted with those services. (My
    VCR was accurate until the analog to digital transition.)
     

  9. Turn them off for a few seconds each day, troll.
     
  10. Peter

    Peter Guest

    My stove's clock is an old fashioned synchronous motor clock. It keeps good
    time. I suspect the problem is noise spikes, and probably not frequency
    inaccuracy.
     
  11. Peter

    Peter Guest

    And if they too have the same problem, I still don't have a solution. My
    electric utility is ignoring me.
     

  12. Idiot. They would HAVE to have the same problem. Duh!
     
  13. AC synchronous clocks do not have any such "detector".

    The frequency IS what determines their operating speed.
     
  14. krw

    krw Guest

    Wrong again, WrongAgain.
    And spikes at the crossings *can* fool them, DimBulb.
     
  15. You're a goddamned retard.

    They are defined by their physical construction.

    No fucking detector.
    There is no detector, and waveform differences can tweak the assembly
    faster for a given baseline frequency or slower.
     
  16. krw

    krw Guest

    A "synchronous clock" does not necessarily contain a synchronous
    motor, AlwaysWrong. They can also be electronic, Dimmie.
    There often is a "zero crossing detector", AlwaysWrong. You can go
    hide now, DimBulb.
     

  17. The only moving part is the rotor. The other "work" part is the coil.
    There are NO electronics.
     
  18. You're an idiot.

    Nope. At the zero crossing, and NOISE that you want to call a spike is
    an order of magnitude smaller than the sine wave that is driving the
    motor.

    In other words... it is negligible. The coil and the rotor of the
    motor are locked to the line frequency, and all but the most extreme
    noise signature is not going to change the speed ANY significant amount
    at all.
     
  19. James Sweet

    James Sweet Guest


    It could be something within your own home causing the noise. Switchmode
    power supply with a bad input filter?
     
  20. Pieyed Piper

    Pieyed Piper Guest


    Buy radio clocks. They update to the atomic clocks in Boulder.
     
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