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Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
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#1
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Why do all the atomic clocks require batteries?
Makes no sence that I woul dbuy aclock to not have to reset the time just so I can play with the batteries instead. Anyone know of a simple analog atomic (naval time by radio) wall clock that uses only 120v ac and no adaptor? (Online specs?) Much obliged. - = - Vasos Panagiotopoulos, Columbia'81+, Reagan, Mozart, Pindus, BioStrategist http://www.panix.com/~vjp2/vasos.htm ---{Nothing herein constitutes advice. Everything fully disclaimed.}--- [Homeland Security means private firearms not lazy obstructive guards] [Urb sprawl confounds terror] [Phooey on GUI: Windows for subprime Bimbos] |
#2
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#3
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On Jun 22, 10:10*am, wrote:
Why do all the atomic clocks require batteries? Makes no sence that I woul dbuy aclock to not have to reset the time just so I can play with the batteries instead. This Atomic Clock works off either AC or DC: http://www.symmetricom.com/products/...tandard/5071A/ Anyone know of a simple analog atomic (naval time by radio) wall clock that uses only 120v ac and no adaptor? (Online specs?) Much obliged. Ah. You want a WWV receiver clock. |
#5
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On 6/22/2012 10:10 AM, wrote:
Why do all the atomic clocks require batteries? Makes no sence that I woul dbuy aclock to not have to reset the time just so I can play with the batteries instead. Anyone know of a simple analog atomic (naval time by radio) wall clock that uses only 120v ac Demand for this product is low. Most people prefer freedom of placement over annual battery replacement. Clocks that project time on the ceiling usually have AC adapters to support the power demand. Mine were distributed by LaCrosse and Oregon Scientific. No idea of current catalog. and no adaptor? That's a problem on several fronts. Anything that plugs in the wall has an additional mountain of testing/certification, paperwork and development costs involved. If you purchase an approved/listed wall wart, all of those problems go away. Most vendors take that route. (Online specs?) Much obliged. - = - Vasos Panagiotopoulos, Columbia'81+, Reagan, Mozart, Pindus, BioStrategist http://www.panix.com/~vjp2/vasos.htm ---{Nothing herein constitutes advice. Everything fully disclaimed.}--- [Homeland Security means private firearms not lazy obstructive guards] [Urb sprawl confounds terror] [Phooey on GUI: Windows for subprime Bimbos] |
#6
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wrote in message
... Why do all the atomic clocks require batteries? Makes no sence that I woul dbuy aclock to not have to reset the time just so I can play with the batteries instead. Anyone know of a simple analog atomic (naval time by radio) wall clock that uses only 120v ac and no adaptor? (Online specs?) Much obliged. - = - Vasos Panagiotopoulos, Columbia'81+, Reagan, Mozart, Pindus, BioStrategist http://www.panix.com/~vjp2/vasos.htm ---{Nothing herein constitutes advice. Everything fully disclaimed.}--- [Homeland Security means private firearms not lazy obstructive guards] [Urb sprawl confounds terror] [Phooey on GUI: Windows for subprime Bimbos] If you don't want a backlight , how much HF electronic smog/ mains coupling is available these days in the average domestic situation. Enough to power LCD and short burst ULF receiver operation ? |
#7
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Your question appears to be about Radio Clocks rather than Atomic Clocks, why not call it what it is?
(Private citizens tend not to own atomic clocks, they normally reside in laboratories, and atomic clocks are powered by mains electricity, not batteries, although there is likely to be an uninterruptable power supply associated with them.) |
#8
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On 6/22/2012 4:22 PM, Dave M wrote:
Adrian C wrote: On 22/06/2012 18:10, wrote: Why do all the atomic clocks require batteries? Makes no sence that I woul dbuy aclock to not have to reset the time just so I can play with the batteries instead. Anyone know of a simple analog atomic (naval time by radio) wall clock that uses only 120v ac and no adaptor? (Online specs?) Much obliged. For flexibility of placement, quartz wall clocks have run on batteries for many years. Having a visible power cable is ugly. Radio controlled clocks have inherited this design requirement unfortunately. USB Power adaptors are pretty small, some not that larger than a plug. Have a look at iPod or mobile phone accessories. If necessary adjust the voltage downwards with a suitable series regulator. Single transistor, resistor, capacitor and a zener should do it. Another quite valid reason for "atomic" clocks being run from batteries is that the clocks query the time sources for the exact time during the night, when signal propagation is best. If the clock loses power during the day, it needs to reset itself when power is restored, but probably won't be able to receive a signal strong enough to be able to make a correction of the time until late at night. Being on battery power solves this problem by never having a loss of power except when the batteries finally die. Well, that is true sometimes, but I have had good results replacing the battery in the middle of the day. The clock normally resets just fine. I am very seldom up in the middle of the night to replace the battery. Bill |
#9
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On Fri, 22 Jun 2012 17:10:12 +0000 (UTC),
wrote: Why do all the atomic clocks require batteries? I think you mean WWVB 60KHz clocks. Atomic clocks are cesium and rubidium standards. Makes no sence that I woul dbuy aclock to not have to reset the time just so I can play with the batteries instead. The problem is that consumer "atomic" clocks only update roughly once per day. The receiver turns on, usually in the middle of the night when 60KHz propagation is best, update, and turn off to conserve battery power. There are continuously operating WWVH receivers available, but not at consumer prices. The batteries also act as a UPS, allowing the clock to continue operating without waiting for night time for WWVB to update the clock. Anyone know of a simple analog atomic (naval time by radio) wall clock that uses only 120v ac and no adaptor? (Online specs?) Much obliged. Heath GC-1000 WWV receiver. I have one that I'm slowly rebuilding. Nifty and rather unique device. http://www.youtube.com/watch?v=rgNtlpSumHg They sell for about $230 on eBay. An unbuilt kit sold for $700. I'm not sure what problem you're trying to solve, but if you don't like replacing a single AA battery every year, you might consider replacing it with a rechargeable battery and solar charger. These already exist: http://www.lacrossetechnology.com/8112w/index.php For the retro effect, I suggest a wind up or hand crank type generator for charging the battery. http://www.k-tor.com/hand-crank-generator/ If that's too much effort, I suggest the atomic water clock: http://www.prlog.org/10596274-the-new-atomic-h2o-clock.html Just add fresh water every 6 months. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
#10
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On Sat, 23 Jun 2012 08:40:54 +0000, FatallyFlawed
wrote: (Private citizens tend not to own atomic clocks, they normally reside in laboratories, and atomic clocks are powered by mains electricity, not batteries, although there is likely to be an uninterruptable power supply associated with them.) Ummm... there are plenty of mere mortals that own cesium and rhubidium standards that drive test equipment and sometimes clocks. The 1 pps output from a GPS or cesium standard is quite useful for driving clocks. http://leapsecond.com http://www.leapsecond.com/hpclocks/ Such atomic frequency standards are also available rather economically on eBay. For example: http://www.ebay.com/itm/280905645392 $86 for rubidium. (Note that rubidium is not really a primary standard but is good enough for most applications). Personally, I prefer a GPSDO (GPS diciplined oscillator) which is more accurate and draws somewhat less power: http://www.ebay.com/itm/170862678745 $158 As for requiring mains electricity, note that the power requirements for the miniature rubidium and cesium fountains makes it possible to operate from batteries. The unit above runs on 12V and burns 11 watts after stabilization. Last time I checked, the GPS satellites, which have internal Kernco cesium clocks, do not require a 20,000km extension cord. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
#11
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Much obliged. I like the idea of solar, but I doubt it charges well
enough. Tried solar clocks in 1985 and 1990 do dismay. - = - Vasos Panagiotopoulos, Columbia'81+, Reagan, Mozart, Pindus, BioStrategist http://www.panix.com/~vjp2/vasos.htm ---{Nothing herein constitutes advice. Everything fully disclaimed.}--- [Homeland Security means private firearms not lazy obstructive guards] [Urb sprawl confounds terror] [Phooey on GUI: Windows for subprime Bimbos] |
#12
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On Sat, 23 Jun 2012 18:02:38 +0000 (UTC),
wrote: Much obliged. I like the idea of solar, but I doubt it charges well enough. Tried solar clocks in 1985 and 1990 do dismay. Solar works for me. I have a solar calculator, solar am/fm/sw emergency radio, solar powered calculator, solar camera battery charger, and various solar chargers. Note that not all of these work in the same way. For example, the solar calculator is an either/or proposition. It either runs on solar or silver-oxide battery. The battery is NOT charged by the solar cells. The limiting factor is the battery type and the self discharge rate, not the solar chargers output. If you use NiMH batteries, which tend to self-discharge at a rather high rate, the solar charger is unlikely to keep up. NiCd are better, but not much. Lead acid are marginal. Supercaps suck. However, Li-Ion and LiPo batteries work quite well for such things. If you want to play, you'll need a LiPo charger that will work with a solar cell. This is what I use: http://www.sparkfun.com/products/10401 Note that the LiPo battery is a nominal 3.7VDC. Fortunately, most "atomic" clocks run on two AAA batteries, which is close enough. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
#13
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On Sat, 23 Jun 2012 09:09:42 -0700, Jeff Liebermann
wrote: On Fri, 22 Jun 2012 17:10:12 +0000 (UTC), wrote: Why do all the atomic clocks require batteries? I think you mean WWVB 60KHz clocks. Atomic clocks are cesium and rubidium standards. SNIP Can Americium be used to build an atomic clock? I understand a little about how cesium and rubidium atoms are used to build atomic clocks but since Americium is used in many smoke detectors wouldn't that be a great science fair project or a Maker Faire project? The world's first truly atomic wall clock? Of course, I suppose it could be argued that radium on clock hands qualify the clock as atomic if radioactivity is the only metric. Eric |
#14
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On Sat, 23 Jun 2012 15:22:39 -0700, wrote:
On Sat, 23 Jun 2012 09:09:42 -0700, Jeff Liebermann wrote: On Fri, 22 Jun 2012 17:10:12 +0000 (UTC), wrote: Why do all the atomic clocks require batteries? I think you mean WWVB 60KHz clocks. Atomic clocks are cesium and rubidium standards. SNIP Can Americium be used to build an atomic clock? Probably not. Anything that will vaporize at reasonable temperatures to form a "fountain" or produces an RF excited gas cell can be used. Americium-241 is solid and melts at about 2600C: http://en.wikipedia.org/wiki/Americium Compare with Cesium-133 boiling at 671C and Rubidium-87 at 688C: http://en.wikipedia.org/wiki/Caesium http://en.wikipedia.org/wiki/Rubidium Actually, it doesn't need to vaporize the entire contents to work. 100C is usually sufficient to create some usable gas. I just wanted to illustrate the relative difference in temperatures required. I understand a little about how cesium and rubidium atoms are used to build atomic clocks but since Americium is used in many smoke detectors wouldn't that be a great science fair project or a Maker Faire project? Ummm... I suggest you read The Radioactive Boy Scout before proceeding. http://www.amazon.com/The-Radioactive-Boy-Scout-Backyard/dp/037550351X The world's first truly atomic wall clock? It's closer than you might suspect. See: http://www.symmetricom.com/media/files/downloads/product-datasheets/DS%5FSA.45sCSAC.pdf http://tf.nist.gov/timefreq/ofm/smallclock/CSAC.html It draws only 0.1 watts. I think it's based on Thallium-205, but I'm not sure. You don't want to know the price. Of course, I suppose it could be argued that radium on clock hands qualify the clock as atomic if radioactivity is the only metric. That reminds me. To vaporize radioactive materials into a gas is not exactly a safe thing to do. The slightest leak, and you've zapped the user. Triple seal the physics package will help, but there's always going to be someone with a can opener and a product liability attorney for a brother in law. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
#15
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Jeff Liebermann wrote in
: If you use NiMH batteries, which tend to self-discharge at a rather high rate, the 2300 mAH AA Everready NiMH(not pre-charged) that I bought at WalMart seem to not have a high discharge rate. I use them for my LED bicycle lighting system. the NiMH cells came with a "smart charger". I charge them maybe once a month. they hold a charge a lot longer than the DeWalt 9.6V NiCd packs for my drill-driver.(and don't have the dendrite problem...) :-) I also have some pre-charged,low self-discharge NiMH cells but they are only 2100 mAH. I'm not saying that is the case for ALL NiMH cells..... but they -may- be improving on that self-discharge rate. It also irks me that the NiMH cells in the stores don't list the mAH rating on the packages. -- Jim Yanik jyanik at localnet dot com |
#16
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wrote in message
... Why do all the atomic clocks require batteries? To prevent AC line noise from drowning out the time signal? Makes no sence that I woul dbuy aclock to not have to reset the time just so I can play with the batteries instead. All the clocks in my house are atomic clocks except for the one on the microwave and stove, and I never have to reset them except for battery changes. Read your owners manual. Battery change is done once a year on new years day. They do DST changes automatically. The only thing to reset is timezone. Anyone know of a simple analog atomic (naval time by radio) wall clock that uses only 120v ac and no adaptor? (Online specs?) Much obliged. - = - Vasos Panagiotopoulos, Columbia'81+, Reagan, Mozart, Pindus, BioStrategist http://www.panix.com/~vjp2/vasos.htm ---{Nothing herein constitutes advice. Everything fully disclaimed.}--- [Homeland Security means private firearms not lazy obstructive guards] [Urb sprawl confounds terror] [Phooey on GUI: Windows for subprime Bimbos] |
#17
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On Sun, 24 Jun 2012 11:28:23 -0500, Jim Yanik
wrote: Jeff Liebermann wrote in : If you use NiMH batteries, which tend to self-discharge at a rather high rate, the 2300 mAH AA Everready NiMH(not pre-charged) that I bought at WalMart seem to not have a high discharge rate. I use them for my LED bicycle lighting system. the NiMH cells came with a "smart charger". I charge them maybe once a month. With typical NiMH, I loose about 20% of charge in the first 24 hrs, and then about 1% per day. I've confirmed this with my own tinkering. After about 3 months, I typically have a half dead battery. It varies hugely with temperatu http://corrosion-doctors.org/Batteries/self-compare.htm http://en.wikipedia.org/wiki/Low_self-discharge_NiMH_battery With the LSD (low self discharge) NiMH batteries, I find that it loses about 10% on the first day, and then very slowly drifts toward about 75% capacity within about 3 months, and then sits there forever. However, such batteries also have less capacity than typical NiMH cells, so you end up with about the same capacity after a few months. The problem with using such batteries is that the clock needs to be able to operate over a long period of time. It could be designed to operate with a battery permanently at 50% capacity, but that would be a waste of money for the battery. Using LiIon would be cheaper and not waste any capacity. However, LiIon and LiPo have another problem. They self deteriorate at full capacity and at high temperatures. http://batteryuniversity.com/learn/article/how_to_prolong_lithium_based_batteries See Table 3. Therefore, Lithium batteries aren't going to work for the clock. I guess one needs to use the same approach as the smart meter vendors are doing. High capacity, non-rechargeable, seems to be the best. http://www.tadiranbat.com/pdf.php?id=metering_international_20_years they hold a charge a lot longer than the DeWalt 9.6V NiCd packs for my drill-driver.(and don't have the dendrite problem...) :-) My Skil something drill and NiCd packs are in my car, which tends to get rather warm. During the summer, I'll have a nearly dead battery pack from self-discharge in about a month. During the winter, the pack will probably last all winter. I also have some pre-charged,low self-discharge NiMH cells but they are only 2100 mAH. I'm not saying that is the case for ALL NiMH cells..... but they -may- be improving on that self-discharge rate. Notice how all the specs are at 25C. Reality requires a higher test temperature. It also irks me that the NiMH cells in the stores don't list the mAH rating on the packages. Not a problem. All the specs are lies, but that's ok, because nobody really understands them. The capacity tests are usually an unrealistically low discharge rates resulting in inflated figures. I'll give Sanyo credit for using C/5 discharge rate, which is more realistic: http://www.eneloop.info/fileadmin/EDITORS/ENELOOP/DATA_SHEETS/HR-3UTGA_data_sheet.pdf -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
#18
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In article ,
Jeff Liebermann wrote: On Sun, 24 Jun 2012 11:28:23 -0500, Jim Yanik wrote: Jeff Liebermann wrote in : If you use NiMH batteries, which tend to self-discharge at a rather high rate, the 2300 mAH AA Everready NiMH(not pre-charged) that I bought at WalMart seem to not have a high discharge rate. I use them for my LED bicycle lighting system. the NiMH cells came with a "smart charger". I charge them maybe once a month. With typical NiMH, I loose about 20% of charge in the first 24 hrs, and then about 1% per day. I've confirmed this with my own tinkering. After about 3 months, I typically have a half dead battery. Try the Sanyo Eneloop cells; they claim about 85% after a year of storage, and my experience using them in my camera confirms that. Isaac |
#19
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On Sun, 24 Jun 2012 21:48:04 -0700, isw wrote:
In article , Jeff Liebermann wrote: On Sun, 24 Jun 2012 11:28:23 -0500, Jim Yanik wrote: Jeff Liebermann wrote in : If you use NiMH batteries, which tend to self-discharge at a rather high rate, the 2300 mAH AA Everready NiMH(not pre-charged) that I bought at WalMart seem to not have a high discharge rate. I use them for my LED bicycle lighting system. the NiMH cells came with a "smart charger". I charge them maybe once a month. With typical NiMH, I loose about 20% of charge in the first 24 hrs, and then about 1% per day. I've confirmed this with my own tinkering. After about 3 months, I typically have a half dead battery. Try the Sanyo Eneloop cells; they claim about 85% after a year of storage, and my experience using them in my camera confirms that. Isaac You didn't use your camera for a year? Hint: Accelerated lifetime tests are usually done at elevated temperatures and for short periods. They are then extrapolated back to room temperatures and longer periods. The curves are well behaved and apply to all chemistries after the initial self-discharge. http://corrosion-doctors.org/Batteries/self-compare.htm The 3rd generation Eneloop claims 70% after 5 years. How to recognize which Eneloop generation: 1st gen - No crown icon 2nd gen - Crown icon near plus sign 3rd gen - Crown and metallic colored letters. I have a set of Eneloop and they are better than ordinary NiMH for self discharge. However, when I counted how many pictures the camera (Canon S5-IS) would take before the charge indicator began to complain, I found that in the short term (about 2 weeks), the ordinary NiMH batteries took more pictures. In the long run, the Eneloop batteries did better. My undocumented wild guess(tm) is that the break even point is at about 2 months. That's because the initial (i.e. immediately after a full charge) for the ordinary NiMH battery is about 2200ma-hr, while the Eneloop are about 1900ma-hr. http://www.eneloop.info/fileadmin/EDITORS/ENELOOP/DATA_SHEETS/HR-3UTGA_data_sheet.pdf http://budgetlightforum.com/node/7336 http://flashlightwiki.com/Eneloop This weekend (ham radio field day), I took about 30 photos with a set of no-name 2300ma-hr NiMh batteries when the charge indicator appeared. The batteries were charged about 4 months ago. I switched to a set of 1st generation Eneloop batteries, that I had charged about 7 months ago, and had previously shot about 100 photos. The charge indicator showed 50%. However, after another 50 photos, the charge indicator still showed 50% implying that there was plenty of capacity left. Yep, Eneloop are good batteries for cameras. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
#20
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On Sun, 24 Jun 2012 21:48:04 -0700, isw wrote:
Try the Sanyo Eneloop cells; they claim about 85% after a year of storage, and my experience using them in my camera confirms that. +1 Jonesy |
#21
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In article ,
Jeff Liebermann wrote: On Sun, 24 Jun 2012 21:48:04 -0700, isw wrote: In article , Jeff Liebermann wrote: On Sun, 24 Jun 2012 11:28:23 -0500, Jim Yanik wrote: Jeff Liebermann wrote in : If you use NiMH batteries, which tend to self-discharge at a rather high rate, the 2300 mAH AA Everready NiMH(not pre-charged) that I bought at WalMart seem to not have a high discharge rate. I use them for my LED bicycle lighting system. the NiMH cells came with a "smart charger". I charge them maybe once a month. With typical NiMH, I loose about 20% of charge in the first 24 hrs, and then about 1% per day. I've confirmed this with my own tinkering. After about 3 months, I typically have a half dead battery. Try the Sanyo Eneloop cells; they claim about 85% after a year of storage, and my experience using them in my camera confirms that. Isaac You didn't use your camera for a year? Of course not; I walk a lot and use it all the time. When the cells in the camera go dead, I replace them with the charged spares I always carry. With "standard" cells, the spares were often near end-of-life when I installed them. With the Eneloops (even with their lower mA-Hr rating), I get several months of use even after carrying them around for some months. --snip-- I have a set of Eneloop and they are better than ordinary NiMH for self discharge. However, when I counted how many pictures the camera (Canon S5-IS) would take before the charge indicator began to complain, I found that in the short term (about 2 weeks), the ordinary NiMH batteries took more pictures. In the long run, the Eneloop batteries did better. Which is completely consistent with the fact the Eneloops gain that lower leakage by using a thicker membrane between the electrodes -- which naturally reduces the mA-Hr capacity. All I wanted was to not run out of battery while on a several-hour walk, and then find that the "spares" were empty too. The Eneloops solved that problem completely. Isaac |
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