Clocks running fast, what could cause this?

Thread Starter

peterdeco

Joined Oct 8, 2019
251
I have a digital clock on a table next to my bed. Over about a 10 year period I have had to replace it 3 times (because they died). All 3 clocks have run slightly fast when plugged into the same outlet. Each one ran 2 minutes fast every 4 weeks. Also, I have a DVD player in my living room with a clock that does the same thing - 2 minutes fast every 4 weeks. We have other clocks that are fine, oven, microwave and another DVD in my wife's office. Any suggestions are appreciated.
 

Yaakov

Joined Jan 27, 2019
1,612
If these clocks are using the line frequency as a time standard, they will deviate over time as the line frequency drifts due to adjustments made on the grid. Overall, the line frequency is very stable because it must be kept in a small range to prevent damage to generating equipment, but it does drift up and down, and will never stay at exactly the nominal frequency (50 or 60 Hz, depending on location).

A quartz-based clock can but won’t necessarily do better than that. One that uses a time stabeard broadcast like those from WWVB will be the most accurate as they will syou most every night and the drift will be limited.
 

Thread Starter

peterdeco

Joined Oct 8, 2019
251
Then why don't the other clocks drift? Incidently, the DVD player that runs fast is plugged into an outlet on the same wall as the fast clock, except it is downstairs.
 

MrChips

Joined Oct 2, 2009
22,106
Clocks using line frequency should not drift from day to day. The frequency is adjusted so that the total number of cycles per day is 24 x 60 x 60 x 60 =5184000 for 60Hz line frequency.

2 minutes in 4 weeks translates to 0.01% deviation which is not bad but could be better for wall clocks.
You can try experimenting using a power line conditioner, something like this:

1580301465314.png
 

ronsimpson

Joined Oct 7, 2019
1,024
I had a automation computer that gained 1/60 of a second every time the elevator started. I had to filter out the high frequency spikes on the power line.
 

Lo_volt

Joined Apr 3, 2014
123
Clocks using line frequency should not drift from day to day. The frequency is adjusted so that the total number of cycles per day is 24 x 60 x 60 x 60 =5184000 for 60Hz line frequency.

2 minutes in 4 weeks translates to 0.01% deviation which is not bad but could be better for wall clocks.
You can try experimenting using a power line conditioner, something like this:
That will depend on how clean the power lines are and how the clock is sensing the line frequency. Brown-outs may also affect timekeeping. We're a bit spoiled here in the US with the frequency and voltage regulation on the power lines. Other countries are not as fortunate.

Time seems to go faster the older I get. :)
My former boss called it "Age related time compression."
 

dl324

Joined Mar 30, 2015
11,907
All 3 clocks have run slightly fast when plugged into the same outlet.
It's common for clocks generating their own timing frequency to drift. Clocks that use line frequency shouldn't drift much (long term accuracy is better than short term).
 
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