Power Grid Change May Disrupt Clocks 439
hawguy writes with an AP story about upcoming tests of greater allowed variation in the frequency of the current carried on the U.S. electric grid: "A yearlong experiment with the nation's electric grid could mess up traffic lights, security systems and some computers — and make plug-in clocks and appliances like programmable coffeemakers run up to 20 minutes fast."
Greater Variation = Lower Quality (Score:2, Insightful)
This is marketing speak for lower quality electricity.
Re:here's the scale (Score:4, Insightful)
3 seconds a day. But twice a year people manually change the time due to summer time.
Wait... You check the accuracy of the minutes when daylight savings comes rather then just hitting the +1 hour button?
Re:Wow... (Score:4, Insightful)
Any clock with the word "quartz" associated with it is using a crystal timebase to determine how long a second, minute, hour, day, etc. are.
http://en.wikipedia.org/wiki/Quartz_clock#Accuracy [wikipedia.org]
Half a second per day, even if the power goes out and you're running off a battery, no matter if the mains frequency wobbles (which it's designed to do anyway).
http://en.wikipedia.org/wiki/Utility_frequency#Stability [wikipedia.org]
The real question (Score:4, Insightful)
The real question is why do devices add the additional circuitry to count pulses off the mains grid rather than add additional circuitry to actually keep time?
A highly accurate crystal costs in the order for $1 for single quantities. A RTC $1-10 depending on feature set. If you already have a microcontroller you don't need the RTC either. Why are clocks etc reliant on an external signal to keep time? How do they keep time when they run on the battery which is a common backup for every $5 alarm you get?
As for streetlights ... Really? How is this not a system which gets timing from some other central authority. I don't know much about street lights, but is this something that will only affect old small town streetlights, or do the shiny new modern LED powered ones in the city act independently enough that they aren't capable of contacting an NTP server?
Re:"Clocks" (Score:3, Insightful)
"Who" would be correct.
It will be a sad day when no one cares enough about language and communication to politely correct someone's grammar mistakes, and when those who try are shouted down by an angry, ignorant mob who are so insecure that they can't handle simple mistakes being pointed out.
Oh, wait...
Re:"Clocks" (Score:1, Insightful)
No, insisting on using "whom" is being an ass. Pointing out that even though it's unnecessary in all cases, in this case it is entirely incorrect, is the opposite of that.
It's a sad state of affairs when educated men get called down as "pedantic" when they deflate someone's ignorant pretentiousness.
Re:"Clocks" (Score:1, Insightful)
You're SO wrong. (Score:4, Insightful)
So untrue. Maybe it was done that way in 1930. But not anymore.
You're wrong.
Line powered clocks with crystal oscillators generally use the line for the reference and the crystal for a backup during power failures.
The line has been far more accurate than a cheap crystal - at least until these goons implement their harebrained scheme.
Re:"Clocks" (Score:4, Insightful)
They understand very well. This isn't about allowing generators to drift out of sync with each other in the short term. It's about not correcting the long-term variations in the grid as a whole.
Household clocks and coffeemakers seem unlikely to be a problem. Most of them nowadays aren't synced to house current, but use quartz oscillators. More likely problems would be old systems which have never been replaced because they've never needed to be; traffic light controllers are a reasonable example.
Re:"Clocks" (Score:0, Insightful)
Jess Christ, shut the fuck up about grammar and talk about the goddamn article!
Holy shit, you want to talk about pedantic? Fuck.
Here's a little bit to get you started: The frequency of your power is going to be all screwy. Discuss.
Gods, some of you people are like fucking teenagers with entitlement complexes.