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#16
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OT.... but I need help
On Thu, 01 Nov 2012 19:59:41 -0400, charlie wrote:
These days, the power companies don't necessarily do what they used to do to keep synchronous motor driven clocks on or close to the correct time. I have in the last couple of years tried to buy a synchronous motor clock, without success. IIRC, I wanted to run such a clock on the output of a 12 VDC to 120 VAC inverter to see how accurate the frequency was. I forget what I used - maybe a plug-in timer switch - to verify the output. Oh - I just remembered - it was an astronomical telescope. The frequency was reasonable, but not up to power-line precision. Good enough to run small appliances, not clocks :-) -- Gene E. Bloch (Stumbling Bloch) |
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#17
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OT.... but I need help
In message , charlie
writes: On 11/1/2012 6:54 PM, Ed Cryer wrote: Ed Cryer wrote: Bob I wrote: Take a close look at the face, and see who manufactured it, then Google. On 11/1/2012 2:04 PM, Ed Cryer wrote: In our local sports centre swimming pool there's a clock on the wall. It keeps good time. I've relied on it for years to time myself. However, every day at 4-00pm exactly it goes into overdrive, and sweeps round covering many hours in a few seconds. Then it resets at just after 4-00pm, and continues normally. [] My best guess is that it's a radio clock, and it self-adjust every day at 4-00pm. But I've googled for "clock speeds up at 4-00pm" and the like and haven't found the answer. [] I have a little radio-controlled clock here at home. It's an Acctim mk 16 9QJ. I've had it about 5 years, and it works fine. But it's a digital display, and I've never seen it do that going into overdrive thing. [] The clock must be running a bit fast, as well as only running in one direction. At the 4:00 setting time, it must go around to stop at the "correct" time, however it determines it. That seems the most likely: it's (a) "radio controlled", but also free-running for when the signal isn't available or for other reasons, (b) only actually corrects itself once a day [or of course twice, but you wouldn't see it at 4 a. m.!], (c) runs a little fast, (d) has a mechanism that can only move forwards [so has to go all the way round when it detects that it needs to go backwards. Come to think about it, it could just stop instead, but maybe they didn't think of that, or maybe they just get the signal once]. [] These days, the power companies don't necessarily do what they used to do to keep synchronous motor driven clocks on or close to the correct time. They do in the UK at least, because (I read somewhere) there are still enough things controlled by such clocks that it matters (say, streetlighting perhaps? Some public clocks, like those on some churches?); they don't keep the frequency spot-on, because that is difficult to do under varying load (you can always drop the voltage, but I think our tolerances are tighter than in US), but they do endeavour to keep the total number of cycles in 24 hours constant enough (by speeding up marginally at night, I guess!) that such clocks remain more or less correct. I think the variation can be up to two or three minutes within a day (I could be wrong about that), but very little in total across many days. -- J. P. Gilliver. UMRA: 1960/1985 MB++G()AL-IS-Ch++(p)Ar@T+H+Sh0!:`)DNAf A clean, neat and orderly desk is a sign of a sick mind. (G6JPG's mind is clearly extremely healthy ...) |
#18
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OT.... but I need help
In message , Gene E. Bloch
writes: On Thu, 01 Nov 2012 19:59:41 -0400, charlie wrote: These days, the power companies don't necessarily do what they used to do to keep synchronous motor driven clocks on or close to the correct time. I have in the last couple of years tried to buy a synchronous motor clock, without success. IIRC, I wanted to run such a clock on the output of a 12 VDC to 120 VAC inverter to see how accurate the frequency was. [] If that's all you want it for, the cheapest type of digital alarm clocks - the sort with four LED digits, and a beep alarm and sometimes a radio - still tend to count mains (line) cycles. Probably impossible to tell before purchase, though. I'd have thought they'd have switched to quartz like everyone else by now, but presumably the circuit design (it's basically one chip, for the clock parts anyway) stabilised some decades ago, and there's been no reason to alter it. -- J. P. Gilliver. UMRA: 1960/1985 MB++G()AL-IS-Ch++(p)Ar@T+H+Sh0!:`)DNAf A clean, neat and orderly desk is a sign of a sick mind. (G6JPG's mind is clearly extremely healthy ...) |
#19
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OT.... but I need help
On 11/1/2012 3:04 PM, Ed Cryer wrote:
In our local sports centre swimming pool there's a clock on the wall. It keeps good time. I've relied on it for years to time myself. However, every day at 4-00pm exactly it goes into overdrive, and sweeps round covering many hours in a few seconds. Then it resets at just after 4-00pm, and continues normally. I've pointed it out to many fellow swimmers; and they stare in amazement, raised eyebrows and a dim expression over the facial features and say they don't know. The other day I finally gave in and asked at Reception what it was all about. She told me that that was the only clock in the Centre that did that, that they weren't interconnected and that she didn't know why. My best guess is that it's a radio clock, and it self-adjust every day at 4-00pm. But I've googled for "clock speeds up at 4-00pm" and the like and haven't found the answer. Some one here must have met one of these things. If so then let me know more. Ed Your kids are swimming so fast, they're slowing time and sending out "time quakes" that interfere with the clock. |
#20
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OT.... but I need help
On Fri, 2 Nov 2012 07:25:05 +0000, "J. P. Gilliver (John)"
wrote: In message , charlie writes: The clock must be running a bit fast, as well as only running in one direction. At the 4:00 setting time, it must go around to stop at the "correct" time, however it determines it. That seems the most likely: it's (a) "radio controlled", but also free-running for when the signal isn't available or for other reasons, (b) only actually corrects itself once a day [or of course twice, but you wouldn't see it at 4 a. m.!], (c) runs a little fast, (d) has a mechanism that can only move forwards [so has to go all the way round when it detects that it needs to go backwards. Come to think about it, it could just stop instead, but maybe they didn't think of that, or maybe they just get the signal once]. I think it would be nearly equally disconcerting, or even more so, if someone were to notice that the clock appears to stop for a period of time every day, versus rapidly advancing. Either way, there's a certain Edgar Allan Poe or Alfred Hitchcock (or Rod Serling's Twilight Zone) quality to the whole thing. Clocks aren't supposed to have spinning hands unless an exorcism is called for. -- Char Jackson |
#21
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OT.... but I need help
On Thu, 01 Nov 2012 22:51:02 +0000, Ed Cryer
wrote: Bob I wrote: Take a close look at the face, and see who manufactured it, then Google. I thought of that. But I'd need a ladder at least ten feet high. It's almost at the top of the wall. Bring a pair of binoculars. |
#22
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OT.... but I need help
On 11/1/2012 8:56 PM, Gene E. Bloch wrote:
On Thu, 01 Nov 2012 19:59:41 -0400, charlie wrote: These days, the power companies don't necessarily do what they used to do to keep synchronous motor driven clocks on or close to the correct time. I have in the last couple of years tried to buy a synchronous motor clock, without success. IIRC, I wanted to run such a clock on the output of a 12 VDC to 120 VAC inverter to see how accurate the frequency was. I forget what I used - maybe a plug-in timer switch - to verify the output. Oh - I just remembered - it was an astronomical telescope. The frequency was reasonable, but not up to power-line precision. Good enough to run small appliances, not clocks :-) Years ago, I remember seeing frequency meters that were made with vibrating reeds. The good ones were quite accurate, but not as accurate as the crystal controlled stuff around today. General Electric used to make relays and other devices designed to work from power frequencies as low as 20Hz. I really don't know who would be using such things today. A/C Generators are interesting creatures when it comes to getting them to put out the exact frequency and voltage desired. Rotating mass has a great deal to do with maintaining frequency. Coils inside the generator (Not the main windings actually producing power) are involved in maintaining the correct voltage. I still remember a local power plant that lost steam, shut down as a result, and had re-start problems. Several car batteries from employees cars in the parking lot were used to get the initial DC exciter voltage. The national power grid wasn't so national at the time. Bad weather had taken down parts of the area grid between local plants, and more or less isolated a primary area supplied by the plant. Syncing generators used to be done with a light connected between them. (Dark Light) I'm sure that there are more highfalutin methods these days. Heck, you can buy camping generators with parallel sync capability built in. My "emergency" 15kw portable generator uses a rudimentary solid state regulator, and a stepping motor for throttle control. The generator has built in windings that control the output voltage with current from the regulator. It's not anywhere perfect, in that there is always some engine surge. Good enough though, that normal household items and electronics are happy, other than synchronous clocks. (Gain a few, loose a few) |
#23
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OT.... but I need help
charlie wrote:
On 11/1/2012 8:56 PM, Gene E. Bloch wrote: On Thu, 01 Nov 2012 19:59:41 -0400, charlie wrote: These days, the power companies don't necessarily do what they used to do to keep synchronous motor driven clocks on or close to the correct time. I have in the last couple of years tried to buy a synchronous motor clock, without success. IIRC, I wanted to run such a clock on the output of a 12 VDC to 120 VAC inverter to see how accurate the frequency was. I forget what I used - maybe a plug-in timer switch - to verify the output. Oh - I just remembered - it was an astronomical telescope. The frequency was reasonable, but not up to power-line precision. Good enough to run small appliances, not clocks :-) Years ago, I remember seeing frequency meters that were made with vibrating reeds. The good ones were quite accurate, but not as accurate as the crystal controlled stuff around today. General Electric used to make relays and other devices designed to work from power frequencies as low as 20Hz. I really don't know who would be using such things today. A/C Generators are interesting creatures when it comes to getting them to put out the exact frequency and voltage desired. Rotating mass has a great deal to do with maintaining frequency. Coils inside the generator (Not the main windings actually producing power) are involved in maintaining the correct voltage. I still remember a local power plant that lost steam, shut down as a result, and had re-start problems. Several car batteries from employees cars in the parking lot were used to get the initial DC exciter voltage. The national power grid wasn't so national at the time. Bad weather had taken down parts of the area grid between local plants, and more or less isolated a primary area supplied by the plant. Syncing generators used to be done with a light connected between them. (Dark Light) I'm sure that there are more highfalutin methods these days. Heck, you can buy camping generators with parallel sync capability built in. My "emergency" 15kw portable generator uses a rudimentary solid state regulator, and a stepping motor for throttle control. The generator has built in windings that control the output voltage with current from the regulator. It's not anywhere perfect, in that there is always some engine surge. Good enough though, that normal household items and electronics are happy, other than synchronous clocks. (Gain a few, loose a few) Niagara Falls had low frequency power generation. Apparently this facility was shut down in 2008. http://www.ieee.org/organizations/pe...eshistory.html And my physics professor relates a story, of studying under incandescent lights that "pulsed" because of the lower frequency used where ever he was living at the time. So somewhere else in North America, they had a lower frequency supply for a time as well. I doubt the individual in question, lived in Niagara Falls or even remotely close to it. Paul |
#24
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OT.... but I need help
Drew wrote:
On 11/1/2012 12:04 PM, Ed Cryer wrote: In our local sports centre swimming pool there's a clock on the wall. It keeps good time. I've relied on it for years to time myself. However, every day at 4-00pm exactly it goes into overdrive, and sweeps round covering many hours in a few seconds. Then it resets at just after 4-00pm, and continues normally. I've pointed it out to many fellow swimmers; and they stare in amazement, raised eyebrows and a dim expression over the facial features and say they don't know. The other day I finally gave in and asked at Reception what it was all about. She told me that that was the only clock in the Centre that did that, that they weren't interconnected and that she didn't know why. My best guess is that it's a radio clock, and it self-adjust every day at 4-00pm. But I've googled for "clock speeds up at 4-00pm" and the like and haven't found the answer. Some one here must have met one of these things. If so then let me know more. Ed Possible atomic clock of some kind? I have a strong suspicion you're right here. Everybody else seems to have gone for radio-control (I did myself as first guess), but look what googling has produced. It looks just like this; http://www.walmart.com/ip/14-Analog-...Pearl/13443480 And then take a look at these hits for images on "Analog Atomic Wall Clock"; there are zillions. http://tinyurl.com/bt95lv3 There must be quite a lot of these things in use around the world. The write-up says; Radio-Controlled Atomic Time Automatically sets to exact time Accurate to the second Automatically updates for daylight saving time (on/off option) 4 time zone settings 14'' Plastic Frame Simple Operation: Insert One AA Alkaline Battery (not included) After signal is received, press Time Zone button to set Four Time Zone Settings Daylight Saving Time Option On/Off Manual Reset Button Ed |
#25
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OT.... but I need help
Ed Cryer wrote:
Drew wrote: On 11/1/2012 12:04 PM, Ed Cryer wrote: In our local sports centre swimming pool there's a clock on the wall. It keeps good time. I've relied on it for years to time myself. However, every day at 4-00pm exactly it goes into overdrive, and sweeps round covering many hours in a few seconds. Then it resets at just after 4-00pm, and continues normally. I've pointed it out to many fellow swimmers; and they stare in amazement, raised eyebrows and a dim expression over the facial features and say they don't know. The other day I finally gave in and asked at Reception what it was all about. She told me that that was the only clock in the Centre that did that, that they weren't interconnected and that she didn't know why. My best guess is that it's a radio clock, and it self-adjust every day at 4-00pm. But I've googled for "clock speeds up at 4-00pm" and the like and haven't found the answer. Some one here must have met one of these things. If so then let me know more. Ed Possible atomic clock of some kind? I have a strong suspicion you're right here. Everybody else seems to have gone for radio-control (I did myself as first guess), but look what googling has produced. It looks just like this; http://www.walmart.com/ip/14-Analog-...Pearl/13443480 And then take a look at these hits for images on "Analog Atomic Wall Clock"; there are zillions. http://tinyurl.com/bt95lv3 There must be quite a lot of these things in use around the world. The write-up says; Radio-Controlled Atomic Time Automatically sets to exact time Accurate to the second Automatically updates for daylight saving time (on/off option) 4 time zone settings 14'' Plastic Frame Simple Operation: Insert One AA Alkaline Battery (not included) After signal is received, press Time Zone button to set Four Time Zone Settings Daylight Saving Time Option On/Off Manual Reset Button Ed According to this, that product uses WWVB. http://www.lacrosse-clock.com/lacrosse_technology.htm The signal strength varies through the day. So if it was having a reception problem, you'd wait until the signal reached peak strength, to see if the clock could pick it up. http://www.nist.gov/pml/div688/grp40/radioclocks.cfm ( http://en.wikipedia.org/wiki/WWVB ) Amazing it runs off one AA alkaline cell. So while you don't have to set the time, the battery is still going to need changing. Paul |
#26
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OT.... but I need help
On Fri, 2 Nov 2012 07:29:38 +0000, J. P. Gilliver (John) wrote:
In message , Gene E. Bloch writes: On Thu, 01 Nov 2012 19:59:41 -0400, charlie wrote: These days, the power companies don't necessarily do what they used to do to keep synchronous motor driven clocks on or close to the correct time. I have in the last couple of years tried to buy a synchronous motor clock, without success. IIRC, I wanted to run such a clock on the output of a 12 VDC to 120 VAC inverter to see how accurate the frequency was. [] If that's all you want it for, the cheapest type of digital alarm clocks - the sort with four LED digits, and a beep alarm and sometimes a radio - still tend to count mains (line) cycles. Probably impossible to tell before purchase, though. I'd have thought they'd have switched to quartz like everyone else by now, but presumably the circuit design (it's basically one chip, for the clock parts anyway) stabilised some decades ago, and there's been no reason to alter it. Interesting. I had thought they all used xtals these days (or even RC networks - what else could explain the lousy timekeeping of a couple I've seen?). Thanks. -- Gene E. Bloch (Stumbling Bloch) |
#27
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OT.... but I need help
Paul wrote:
Ed Cryer wrote: Drew wrote: On 11/1/2012 12:04 PM, Ed Cryer wrote: In our local sports centre swimming pool there's a clock on the wall. It keeps good time. I've relied on it for years to time myself. However, every day at 4-00pm exactly it goes into overdrive, and sweeps round covering many hours in a few seconds. Then it resets at just after 4-00pm, and continues normally. I've pointed it out to many fellow swimmers; and they stare in amazement, raised eyebrows and a dim expression over the facial features and say they don't know. The other day I finally gave in and asked at Reception what it was all about. She told me that that was the only clock in the Centre that did that, that they weren't interconnected and that she didn't know why. My best guess is that it's a radio clock, and it self-adjust every day at 4-00pm. But I've googled for "clock speeds up at 4-00pm" and the like and haven't found the answer. Some one here must have met one of these things. If so then let me know more. Ed Possible atomic clock of some kind? I have a strong suspicion you're right here. Everybody else seems to have gone for radio-control (I did myself as first guess), but look what googling has produced. It looks just like this; http://www.walmart.com/ip/14-Analog-...Pearl/13443480 And then take a look at these hits for images on "Analog Atomic Wall Clock"; there are zillions. http://tinyurl.com/bt95lv3 There must be quite a lot of these things in use around the world. The write-up says; Radio-Controlled Atomic Time Automatically sets to exact time Accurate to the second Automatically updates for daylight saving time (on/off option) 4 time zone settings 14'' Plastic Frame Simple Operation: Insert One AA Alkaline Battery (not included) After signal is received, press Time Zone button to set Four Time Zone Settings Daylight Saving Time Option On/Off Manual Reset Button Ed According to this, that product uses WWVB. http://www.lacrosse-clock.com/lacrosse_technology.htm The signal strength varies through the day. So if it was having a reception problem, you'd wait until the signal reached peak strength, to see if the clock could pick it up. http://www.nist.gov/pml/div688/grp40/radioclocks.cfm ( http://en.wikipedia.org/wiki/WWVB ) Amazing it runs off one AA alkaline cell. So while you don't have to set the time, the battery is still going to need changing. Paul I find that hard to believe, too. My little Acctim digital radio clock needs two AAs. But it also displays date, temp and phase of moon. Mind you, I can't recall having ever changed the batts since I got the thing. Ed |
#28
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OT.... but I need help
On Fri, 02 Nov 2012 11:27:53 -0400, charlie wrote:
On 11/1/2012 8:56 PM, Gene E. Bloch wrote: On Thu, 01 Nov 2012 19:59:41 -0400, charlie wrote: These days, the power companies don't necessarily do what they used to do to keep synchronous motor driven clocks on or close to the correct time. I have in the last couple of years tried to buy a synchronous motor clock, without success. IIRC, I wanted to run such a clock on the output of a 12 VDC to 120 VAC inverter to see how accurate the frequency was. I forget what I used - maybe a plug-in timer switch - to verify the output. Oh - I just remembered - it was an astronomical telescope. The frequency was reasonable, but not up to power-line precision. Good enough to run small appliances, not clocks :-) Years ago, I remember seeing frequency meters that were made with vibrating reeds. The good ones were quite accurate, but not as accurate as the crystal controlled stuff around today. General Electric used to make relays and other devices designed to work from power frequencies as low as 20Hz. I really don't know who would be using such things today. A/C Generators are interesting creatures when it comes to getting them to put out the exact frequency and voltage desired. Rotating mass has a great deal to do with maintaining frequency. Coils inside the generator (Not the main windings actually producing power) are involved in maintaining the correct voltage. I still remember a local power plant that lost steam, shut down as a result, and had re-start problems. Several car batteries from employees cars in the parking lot were used to get the initial DC exciter voltage. The national power grid wasn't so national at the time. Bad weather had taken down parts of the area grid between local plants, and more or less isolated a primary area supplied by the plant. Syncing generators used to be done with a light connected between them. (Dark Light) I'm sure that there are more highfalutin methods these days. Heck, you can buy camping generators with parallel sync capability built in. My "emergency" 15kw portable generator uses a rudimentary solid state regulator, and a stepping motor for throttle control. The generator has built in windings that control the output voltage with current from the regulator. It's not anywhere perfect, in that there is always some engine surge. Good enough though, that normal household items and electronics are happy, other than synchronous clocks. (Gain a few, loose a few) Thanks for the education. I have seen the vibrating reed frequency meters before, but for syncing generators on the ship I served on, there was a phase meter wired between them. There was no reserve power, battery or diesel, so when we lost both generators, which were steam powered, it was hard to get going again. Someone had to manually pump fuel into the boiler firebox long enough to get the generators going. Fun. I'm glad it only happened once while I was on board :-) -- Gene E. Bloch (Stumbling Bloch) |
#29
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OT.... but I need help
On Fri, 02 Nov 2012 18:59:39 +0000, Ed Cryer wrote:
Paul wrote: Ed Cryer wrote: Drew wrote: On 11/1/2012 12:04 PM, Ed Cryer wrote: In our local sports centre swimming pool there's a clock on the wall. It keeps good time. I've relied on it for years to time myself. However, every day at 4-00pm exactly it goes into overdrive, and sweeps round covering many hours in a few seconds. Then it resets at just after 4-00pm, and continues normally. I've pointed it out to many fellow swimmers; and they stare in amazement, raised eyebrows and a dim expression over the facial features and say they don't know. The other day I finally gave in and asked at Reception what it was all about. She told me that that was the only clock in the Centre that did that, that they weren't interconnected and that she didn't know why. My best guess is that it's a radio clock, and it self-adjust every day at 4-00pm. But I've googled for "clock speeds up at 4-00pm" and the like and haven't found the answer. Some one here must have met one of these things. If so then let me know more. Ed Possible atomic clock of some kind? I have a strong suspicion you're right here. Everybody else seems to have gone for radio-control (I did myself as first guess), but look what googling has produced. It looks just like this; http://www.walmart.com/ip/14-Analog-...Pearl/13443480 And then take a look at these hits for images on "Analog Atomic Wall Clock"; there are zillions. http://tinyurl.com/bt95lv3 There must be quite a lot of these things in use around the world. The write-up says; Radio-Controlled Atomic Time Automatically sets to exact time Accurate to the second Automatically updates for daylight saving time (on/off option) 4 time zone settings 14'' Plastic Frame Simple Operation: Insert One AA Alkaline Battery (not included) After signal is received, press Time Zone button to set Four Time Zone Settings Daylight Saving Time Option On/Off Manual Reset Button Ed According to this, that product uses WWVB. http://www.lacrosse-clock.com/lacrosse_technology.htm The signal strength varies through the day. So if it was having a reception problem, you'd wait until the signal reached peak strength, to see if the clock could pick it up. http://www.nist.gov/pml/div688/grp40/radioclocks.cfm ( http://en.wikipedia.org/wiki/WWVB ) Amazing it runs off one AA alkaline cell. So while you don't have to set the time, the battery is still going to need changing. Paul I find that hard to believe, too. My little Acctim digital radio clock needs two AAs. But it also displays date, temp and phase of moon. Mind you, I can't recall having ever changed the batts since I got the thing. Ed Clearly the second battery is for the moon phase :-) Imagine the battery situation if these things had to use vacuum tubes (valves). -- Gene E. Bloch (Stumbling Bloch) |
#30
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OT.... but I need help
On 01/11/2012 23:52, Paul wrote:
Fokke Nauta wrote: On 01/11/2012 20:04, Ed Cryer wrote: In our local sports centre swimming pool there's a clock on the wall. It keeps good time. I've relied on it for years to time myself. However, every day at 4-00pm exactly it goes into overdrive, and sweeps round covering many hours in a few seconds. Then it resets at just after 4-00pm, and continues normally. I've pointed it out to many fellow swimmers; and they stare in amazement, raised eyebrows and a dim expression over the facial features and say they don't know. The other day I finally gave in and asked at Reception what it was all about. She told me that that was the only clock in the Centre that did that, that they weren't interconnected and that she didn't know why. My best guess is that it's a radio clock, and it self-adjust every day at 4-00pm. But I've googled for "clock speeds up at 4-00pm" and the like and haven't found the answer. Some one here must have met one of these things. If so then let me know more. Ed Well, we got a radio controlled alarm here. It should be synced by a Frankfurt radio time transmittor. Really state of the art. I would call it state of a fart. Many times it shows a different time. Always a surpise when you look for the time. It varies from minus to plus a few hours. So your clock (radio controlled as well) ain't too bad. Fokke In North America, there is WWV. http://en.wikipedia.org/wiki/WWV_(radio_station) There is also GPS, but that's at a higher frequency, and may be harder to receive inside a building. Whatever radio source is uses, the format of signal would have to be simple enough, for a cheap synchronization design. With processors being as cheap as they are now, that wouldn't present a problem today. But might have been an issue when that particular clock was built. This device claims to set itself via radio signal. http://www.amazon.com/Sangean-Americ.../dp/B0010HUAIO "Radio Controlled clock available for DCF/WWVB/MSF/JJY" http://en.wikipedia.org/wiki/DCF77 http://en.wikipedia.org/wiki/MSF_time_signal http://en.wikipedia.org/wiki/JJY Interesting collection of frequencies. The low frequencies are in the same range as the ones submarines use. Whereas the WWV thing is shortwave. Paul Hey, our alarm clock listens to DCF77. Wasn't aware of that! Interesting info! Fokke |
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