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Author Topic: AP EXCLUSIVE: Power grid change may disrupt clocks  (Read 2249 times)
KK7UV
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« on: June 26, 2011, 05:31:45 AM »

For discussion:  What will an altered frequency do for radio equipment?

http://www.cbsnews.com/stories/2011/06/24/ap/tech/main20074275.shtml


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KE3WD
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« Reply #1 on: June 26, 2011, 07:16:08 AM »

The old synchron motor analog clocks are the ones that need the line frequency to remain constant in order to keep good time. 

That AP story references modern timekeeping devices such as coffeemakers, digital clocks, and the like, every one I've examined uses its own quartz-based timekeeping oscillator that is independent of AC line frequency. 

As for Amateur radio gear and even gear made for other services, highly unlikely that the amount of variation described would affect any of them at all. 

The analog synchron clock is today an antique and there are likely not very many left in daily use. 

There will probably be a few really old systems, such as the synchron clock systems in use in some public schools and other larger facilities that may need to be revisited from such a change - and that is what I think the power company engineers are talking about when they say in the article that they would like to implement the change and see who reports what, when and how.  There would still be a way to workaround with the old systems, if total replacement proved to be cost prohibitive, a good engineer could design a retrofit power system for those large system synchron clocks that, locked to its own quartz, could keep 'em running with even better precision and accuracy than they've ever enjoyed from powerline frequency control. 

This is NOT another "end-of-the-world-as-we-know-it" situation IMO. although Hammond tonewheel organists may suddenly find that they may not enjoy being the church's or band's Tuning Reference any longer...


73
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K8AXW
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« Reply #2 on: June 26, 2011, 09:01:41 PM »

True, it might not be the "end of the world" problem.... but I believe it will create a whole host of new problems that has to be delt with.  Anything controlled by line frequency.  Like your VCR, DVR most clocks, digital as well as analog....(Not all digital clocks use crystal frequency generators) computers, industrial controls......time using your imagination will flesh out this scenerio.

I spent many years operating 7 turbo-generators and manually maintaining 60Hz with a commercial power company controlled analog clock which was compared to an identical analog clock on our system. 

If the power companies let the frequency sag just 0.5 second, (59.5Hz) at the end of 8 hours your clocks will have slowed down 4 minutes!  Now if you want to record a TV program, you will lose 4 minutes of that program. That's just for 1/2 Hz!  If the frequency is allowed to sag much below that serious things happen in industry. 

This is just another way the "bean counters" want to save a few bucks!

IT NEVER STOPS!


 


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KE3WD
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« Reply #3 on: June 27, 2011, 06:25:17 AM »

My imagination is quite well, thank you very much. 

Over the years I have also been inside *many* consumer electronics items, and again say that the majority of clocks in them do indeed use the quartz timebase and not the line frequency.  It is simply cheaper to implement and uses less parts.  Also, that allows them to run from DC power supply, whether or not the unit is battery powered is irrelevant, it is simply more cost effective from the manufacturing standpoint to go with the quartz timebase.  And no need to tap into the AC line and have to deal with yet another consumer safety issue there (isolation, etc.). 

Do you know the story behind the synchron clock and the power companies?

Laurens Hammond, inventor of the Hammond Tonewheel Organ that bears his name, started out making syunchronous motors to drive clocks,  Matter of fact, his firm was originally named the "Hammond Clock Co." - a name which he kept for some time after his company made more electric tonewheel organs than clocks. 

Laurens was based in Chicago, Ill. and while he knew he was perhaps onto something with the synchron clock, there was a problem that prevented them from catching on in sales and that was the powerline frequency.  Back then, there was no incentive for power generation company engineers to be all that concerned with nailing the frequency.  And they didn't. 

Laurens Hammond hit on a way to make that happen. 

He presented his clocks as gifts to the executives at the power plant. 

Sure enough, they all wanted their clocks to keep time and soon directed the plant engineers and technicians to keep that line frequency stable. 

I don't know of *any* appliances that have digital clocks in them that do not use the quartz timebase.  There may be some out there, my bet would be that they are few and far between, but I am not a betting man. 


73
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K8AXW
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« Reply #4 on: June 27, 2011, 08:17:36 AM »

3WD:  First of all, I never attacked your "imagination."  OK?  I just said that all one had to do is use their imagination to come up with other items that uses the 60Hz line frequency for timing. (Paraphrased)

On item I found interesting.  Using a quartz timebase uses less parts? 

The history lesson was interesting.  Thanks for that.  Rather than pursue this thread any further, I think the best thing to do is wait and see if the power grid (companies) get their permission to try this experiment.  If they do the experiment, it is going to be interesting to see the fallout.  At least that is what I'm going to do OM.

However, being a pessimistic old man, I can see the consumer getting another one in the neck.
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KE3WD
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« Reply #5 on: June 27, 2011, 05:26:30 PM »

The widespread use of digital clocks means that there are plenty of one-chip solutions for the electronics designer.  One chip, one quartz, couple of caps and maybe a resistor or two, plus a clock led or other readout. 

Syncing to Line Frequency, on the other hand, with low voltage solid state stuff, would require more parts.  It also requires tying in to the AC line *after* the required isolation of transformer/power supply in such fashion as to be able to pass UL, etc.  Optoisolator may be used here, but that adds yet another level of parts count to the thing. 

There is no need to sync from line frequency in the digital clock.  That's what the quartz is for, and it is at a much higher frequency, which translates to much better precision and even accuracy up to a point. 


73
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K8AXW
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« Reply #6 on: June 27, 2011, 09:04:51 PM »

Until just recently, I had 3 digital clocks that uses the AC line for frequency control.  All that was used was a couple resistors and a couple caps.  Period.  I still use two clocks that use 60Hz AC for frequency control.

I'm not saying that this is the present norm for the whole country but I am saying that there are enough clocks out there that will be affected by this "experiment" and the results will cost the consumers money because the bean counters with the power grid has found a way to save money.

At one time we had the best telephone system in the world, bar none.  Now we have a hodgepodge group of telephone providers and the consumer has paid dearly for this.  Now the power grid people wants to play with our power.

We've spent a lot of words about clocks.  Industry will take a big hit in the pocketbook if the get into this "experiment."  I know what I'm talking about here because I spent 40 years working for a very large paper mill in their power department.  I've seen first hand what happens when the line frequency is allowed to sag.

I'd venture to say permission to conduct this experiment will be contested.
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KE3WD
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« Reply #7 on: June 28, 2011, 07:37:15 AM »

Gee, I wonder what all those inexpensive digital watches out there use for a timebase? 

Commercial systems that need the tight frequency due to use of synchronous timing motors, etc. are a situation where a smart engineer can design a suitable situation that controls that frequency, extending the life of the equipments.  Which may have to happen if the power companies do indeed go down that path. 

Sounds like a paid job situation to this engineer... 

73
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KB1GMX
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« Reply #8 on: July 09, 2011, 06:27:53 PM »

Digital watches all use 32768hz crystal it's a common standard.

As to motor controls.  Any systems out there that need precise speed are all
controlled off DC or AC drive systems.  The only guys hanging off the line are
those needing raw HP and speed variations are not an issue (within bounds).

This change doesn't affect them at all.

As to the line frequency timed gear, the error is not bad at all.  The reason
they don't wander further is their gear is all designed for 60Hz and major
excursions do make a difference!  The primary reason as I understand for
excursions at all is to sync one generation facility to another and also to
move load as the facility that leads the grid in phase is carrying the load.

Allison
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KE3WD
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« Reply #9 on: July 10, 2011, 07:24:34 AM »

They likely won't believe you Allison. 

Far more exciting to get angry over nothing these days.

There still may be some process control gear around that uses synchron motors for timing switching off of rotating cams, etc.  Even these may or may not need the precise AC line frequency control, and if some do, I don't mind being called to design a pcb to go between the AC and the separate motor that could lock the timing to quartz.  I have a feeling that the whole idea behind trying it and seeing who complains is based on the well-informed data already at hand.  Which is that, while there *may* prove to be some exceptions, those exceptions have become few and far between these days. 


73
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W5DQ
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« Reply #10 on: July 14, 2011, 11:07:51 AM »

Digital watches all use 32768hz crystal it's a common standard.


It's the standard color burst generator frequency in color TV's. Lots of things use this frequency as a base oscillator freq. Cheap and easy available parts (on upon a time).
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Gene W5DQ
Ridgecrest, CA - DM15dp
www.radioroom.org
KE3WD
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Posts: 5694




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« Reply #11 on: July 15, 2011, 08:11:08 AM »

The 3.58 MEGAhertz color burst crystal isn't anywhere near the much lower frequency of the 32768hz (32.768 KILOhertz) clock crystal.  

(A note to those waiting with baited breath to correct me, "three-five-eight" is what TV pros call the 3.579545 MHz Color Burst frequency...) 


73
« Last Edit: July 15, 2011, 08:14:01 AM by KE3WD » Logged
W5DQ
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« Reply #12 on: July 15, 2011, 11:00:18 AM »

The 3.58 MEGAhertz color burst crystal isn't anywhere near the much lower frequency of the 32768hz (32.768 KILOhertz) clock crystal.  

(A note to those waiting with baited breath to correct me, "three-five-eight" is what TV pros call the 3.579545 MHz Color Burst frequency...) 


73
You are correct. My bad. I just read the number wrong and posted without being careful. Thanks for pointing out the error.

Gene W5DQ
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Gene W5DQ
Ridgecrest, CA - DM15dp
www.radioroom.org
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