My AC digital clocks run fast. Cheap fix?

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.

There are requirements for long-term (30-day) accuracy.

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Here, in Crete, south Greece, the local control centre of the utility

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?

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.)

Get a cheap electric clock that runs on a synchronous motor. See if when it uses the power line frequency, which all these cheap clocks do, if they have long term inaccuracy. Even quartz crystal clocks can be off. Most new VCR synchronize off of PBS YV statops.

Bill

Do your neighbours experience the same problem? Does anyone a few blocks away have it too? You might be on a bad spur that has a lot of spikes or a source of interference connected to it.

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.

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

If that is the case, you need line filtering. A surge protector might do it. Use the equivalent of what is used to keep rf out of screen rooms. A screen room filter costs too much but you could assemble something good enough much cheaper.

Bill

Surge protectors (eg. MOVs) do not clamp spikes that are at or below the mains voltage, yet these spikes can still play havoc with the mains frequency detector in clocks. EMI filters (L's and C's in a box) will do a better job. You may need a strong one!

G.

Idiot. They would HAVE to have the same problem. Duh!

AC synchronous clocks do not have any such "detector".

The frequency IS what determines their operating speed.

Wrong again, WrongAgain.

And spikes at the crossings *can* fool them, DimBulb.

The only moving part is the rotor. The other "work" part is the coil. There are NO electronics.

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.

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

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

It's amazing how some people are so quick to hurl insults that they never bother to carefully read the post they are replying to. How would buying all atomic clocks solve the problem with my VCRs and DVR?