12 ms·
First atomic clock wristwatch (2003)
- notum 6y agoReal men demand real time. Technology. Elegance. Tradition. HP Cesium line, the man's watch.
- hinkley 6y agoWarranty void if product is submerged in water over 100m deep, travels at greater than 30,000 km/s, or is taken into outer space.
- botto 6y agoWhat about if approaching a super dense point where space-time warps?
- notum 6y agoSpacetime anomalies are covered only from the observer's reference point. Doh!
- hinkley 6y agoWe can certainly add that clause. But might we suggest that if you do encounter such a scenario within the earth's atmosphere, that you should address that situation immediately? Otherwise there may soon be no circuit court judges available to hear your case.
- rob74 6y agoYou should stay away from those, the damned thing is already heavy enough as it is...
- elihu 6y agoIf the warranty expires, is the duration based on the manufacturer's reference frame, or the watch's?
- tyingq 6y agoFor as little as $47,500 USD. https://www.ebay.com/itm/HP-Agilent-Keysight-5071A-US39301641-Primary-Frequency-Standard/143819446324?epid=1026491491&hash=item217c4e9834%3Ag%3AHwcAAOSwp6xfoFDx&LH_BIN=1 https://www.ebay.com/itm/HP-Agilent-Keysight-5071A-US3930164...
- mikewarot 6y agoCesium beam atomic clocks rely on an internal supply of cesium metal contained in an oven. This supply usually lasts 5-10 years, after which the tube containing the physics package needs to be replaced. They are interesting to work on, once you get the hang of it, you can diagnose them in an hour or two. Rubidium cell atomic clocks, on the other hand have a vapor cell which is a closed tube, and doesn't get expended. Thus Rubidium clocks have far longer service lives. You can find them surplus on Ebay for less than $200. The stability is slightly less, but still far more accurate than most electronics technicians need to do adjustments and calibrations. [Update - Far more than you ever thought you wanted to know about atomic clocks] The main difference between an atomic clock and a quartz crystal oscillator is that in a crystal oscillator, you have a continuous signal that is generated from the circuitry and passed through the crystal, and amplified in a feedback loop. A crystal oscillator can be made with a single transistor and a few passive components. In an atomic clock, there is a stabilized quartz oscillator, which actually keeps time, but it is then steered up or down in frequency slightly by using a harmonic of that frequency, along with a very slight amount of frequency modulation, to inject into a cavity containing the atom of interest. In Cesium (Caesium outside the US) beam clocks, the physics package is all packed inside a large vacuum tube. Inside the tube is an oven with microscopic holes in the top containing cesium metal, the oven is heated to about 200 degrees. A small stream of individual atoms exit. Those atoms pass through a magnetic field which diverts them according to spin. The atoms then drift through a microwave chamber where there is a 9.129 Ghz signal imparted. If the frequency of the signal exactly matches the natural resonance frequency of the cesium atom, its spin will flip. On the other side of the drift chamber, a second magnet selects only those atoms which have flipped state, all other atoms are diverted and trapped. Then the atoms encounter a hot wire with high voltage where they are ionized, them passed through another magnetic field which is a mass spectrometer, this serves to filter out impurities and contaminant that are present in the tube. There is a fine slit that allows entrance only to the cesium beams (now regardless of their spin), and they imping upon a plate in a photomultiplier. The net result of all this physics is that if you have exactly the correct frequency, there is a DC current of a microampere or so output, too high or too low, and the output drops quickly. The line width is on the order of a few hertz. To sample against this, the quartz oscillator is multiplied in frequency the appropriate amount using multipliers and phase locked loops, and combined with a very small amount of frequency modulation at 137 hertz. The DC output of the tube varies with the modulation... if it increases with increasing frequency, the reference clock is too slow... if it is out of phase, the reference clock is too fast, and if you get a 274 hz second harmonic, you are right on frequency. They take about 10-20 minutes to warm up and lock. There are some adjustments, and it is possible to have them locked on the wrong frequency if you aren't careful. Cesium clocks, used, are on the order of $5000 -- Rubidium clocks are easier to use... they are also quartz oscillators probing with FM signals, but instead of a stream of atoms, there is a lamp with one isotope of rubidium which is then passed through a chamber with microwaves and the other isotope of rubidium... if the frequency is just right, the light transmission dips by 1%, and this is used to lock the oscillator. Rubidium standards are about 10 times less stable, but have far longer service lives, and can be had used for about $200.
- avalys 6y agoMore like "armwatch" I'd say.
- obilgic 6y agoWhat are the current use cases for atomic clocks?
- formerly_proven 6y agoAdjusting clocks that aren't atomic. Cellular base stations used to have rubidium sources disciplined to GPS as a reference frequency for synthesis. AIUI, put the expensive, precise part in the base station, have the cheap handset lock onto that. Free accuracy. Not sure if they still do it that way. That's where all the cheap used rubidium sources on eBay come from.
- SAI_Peregrinus 6y agoAlso GPS (and other GNSS system) satellites themselves have atomic clocks.
- tyingq 6y agoLow latency time source for stuff like Spanner that appreciates times that are the same across disparate data centers?
- jdsully 6y agoThey have applications in the database space, e.g. see Google's spanner: https://www.theverge.com/2012/11/26/3692392/google-spanner-atomic-clocks-GPS https://www.theverge.com/2012/11/26/3692392/google-spanner-a...
- jdxcode 6y agohow much does it weigh?
- tvb 6y agoAbout 70 lbs (30 kg), so not difficult to lift or carry with two hands. But it took a real man (my brother-in-law, construction worker) to hold it outstretched like you see in the photo.
- nullc 6y agoAnd all this time I felt like a total wimp for finding that photo really daunting. 5071a is lighter with the batteries out, but not that light! :)
- stakkur 6y agoLess than the embarrassment of being the only person on your block without one.
- mikepurvis 6y agoDon't miss a previously-featured-on-HN article from the same site about taking an atomic clock up Mt. Rainier to check if you would actually gain billionths of a second as predicted by GR: http://www.leapsecond.com/great2005/ http://www.leapsecond.com/great2005/ And pictures: http://www.leapsecond.com/great2005/tour/ http://www.leapsecond.com/great2005/tour/
- systemvoltage 6y agoI am realizing how ordinary my childhood was.
- mikepurvis 6y agoI know! Three atomic clocks riding in the middle and the kids in the back playing on a GameCube.
- serf 6y agoas a track marshal that routinely denies track entry (probably every single event) due to inappropriate battery mounting and wire mismanagement, these pictures terrify me. It's a cute experiment with the kids, and i'm glad they got away without injury -- but on the other hand i've witnessed first hand what a lead battery that is floating around the cabin can do during a wreck -- and what I witnessed was, sadly, deadly for the driver. single orientation nylon straps that are strapping heavy square objects against foam cushioned seats and sandwiching the chaos with human meat on both sides. It's a recipe for disaster regardless of what vector the force of the impact comes from -- and that's ignoring the batteries. Please folks , when you drive a vehicle the heavy stuff gets strapped behind a bulkhead at the front or rear of the car, or atop the car with appropriate and well-tested strapping & mounting equipment. Don't risk your life for the sake of convenience.
- throwaway0a5e 6y agoDo you honestly expect these people to add proper tie down points to the floor of a minivan for a one time trip? The batteries are behind a seat row, the stuff in the seat is strapped in, the loose stuff is in the pass front foot well per OSHA guidelines (I figure most here worship at that altar). It'll be fine. They're not tracking the minivan. I know that every time something like this is posted everyone likes to swoop in and talk about how X or Y is unsafe and you need eye protection every time you pick up a screwdriver and fall protection every time you even glance sideways at a step ladder because that's a way to score easy virtue points but it just comes across as tone deaf posturing. They aren't driving the van around like this 40hr a week for an entire career likewise it is not reasonable to expect them to implement a tie down solution that scales to that level.
- dang 6y agoIf curious see also 2014 https://news.ycombinator.com/item?id=7596922 https://news.ycombinator.com/item?id=7596922 2010 https://news.ycombinator.com/item?id=1870559 https://news.ycombinator.com/item?id=1870559
- tvb 6y agoThanks, DanG. Author here. I happen to be reading HN right now if anyone has questions about cesium clocks or using them to demonstrate relativistic effects. This is just a DIY hobby of mine.
- ajford 6y agoIt's a bit melancholy now with the collapse and all, but just wanted you to know a paper copy of that image was taped up on the Clock Room wall at Arecibo Observatory when I left (somewhere in 2015).
- CamperBob2 6y agoTempus edax rerum :(
- deleted 6y ago[deleted]
- xkeysc0re 6y agoHow hard are cesium clocks to maintain / repair? I've seen some listed online for ~1k with various startup errors and always thought it'd be fun to fix one up, but I'm very much an entry level atomic clock enthusiast!
- tvb 6y agoIf you have experience with analog and digital electronics it's not very hard. Atomic clocks were part of Hewlett-Packard's glory days and in that era the user got full documentation, schematics, theory, trouble-shooting guides, etc. The manuals are all still available online or on eBay. There is also the time-nuts mailing list where hundreds of us share questions and experiences with repairing and running old atomic clocks. The archive is 20 years deep so there's lots of good info on bringing dead cesium and rubidium clocks back to life: http://leapsecond.com/time-nuts.htm http://leapsecond.com/time-nuts.htm The one problem is if the old cesium clock you buy has "run out of gas". The quantum mechanics physics experiment encapsulated inside the tube is a one-way street so once the tube runs out of cesium one has to replace it. The typical solution is to buy a few cesium clocks over time on eBay and mix parts until you have one that works well.
- deleted 6y ago[deleted]
- deanmen 6y agoThere is an actual atomic clock watch on the market that is a little bit smaller: https://www.hodinkee.com/articles/introducing-the-bathys-cesium-133-atomic-clock-watch https://www.hodinkee.com/articles/introducing-the-bathys-ces...
- mikestew 6y agoNote that bathyshawaii.com is likely no longer owned by the maker, and it most certainly is NSFW (oh, keep scrolling).
- Teknoman117 6y agoThese days it's not as complicated. Microchip has a line of "chip scale" atomic clock modules you could use to make one. Not sure what the pricing is. https://www.microsemi.com/product-directory/clocks-frequency-references/3824-chip-scale-atomic-clock-csac#overview https://www.microsemi.com/product-directory/clocks-frequency...
- sjruckle 6y agoOnly $5,100.20 from Mouser https://www.mouser.com/ProductDetail/Microchip-Technology/090-03240-001/?qs=w%2Fv1CP2dgqpPJJa0jwVC6w%3D%3D https://www.mouser.com/ProductDetail/Microchip-Technology/09...
- sosuke 6y agoIs that the same one as this is using? https://www.hodinkee.com/articles/richard-hoptroffs-atomic-watch-prototype-combines https://www.hodinkee.com/articles/richard-hoptroffs-atomic-w...
- reportingsjr 6y agoIndeed it is!
- GekkePrutser 6y agoI wonder if it's safe to wear a radioactive source on the wrist like that. Or is it not strong enough to matter?
- deleted 6y ago[deleted]
- peterfisher 6y ago"When engineering doesn't involve product or design"
- amenghra 6y agoLeaves car full of batteries and cables running in front of a lodge for two days. If this were 2020, every three letter agency would be surrounding the place.
- tvb 6y agoI anticipated that, so I had relativity books and physics magazines with pictures of Einstein on the front seat just in case we got stopped and the officer wanted a quick lesson in the fun of measuring time dilation. It was 2005, the 50th anniversary of the first cesium clock, the 100th anniversary of the theory of relativity, so it was also a current news topic. Actually, a three letter agency did ask me what was going on: NPS, the National Park Service! But they kindly allowed us to park in front of the Lodge for the weekend. The advice I was given by old timers was to refer to the electronics simply as accurate clocks instead of atomic clocks or cesium clocks because many people false trigger on words like cesium or atomic. You'll notice that the official name on the front panel of a 5071A is "Primary Frequency Standard".
- amenghra 6y agoLove it! What's the cheapest clock you can purchase (used or new) where you can still do a similar experiment (i.e. that's accurate enough to measure dilatation over a day/week/month period of time)?
- mothsonasloth 6y agoThis is interesting, I would like to get an Atomic Clock (5071A Primary Frequency Standard), however I can't seem to find any in the UK (Ebay, LocalEbay or other places) Are they a restricted item because of the radio-isotope?
- fsh 6y agoThe Cesium isotope used in atomic clocks (133Cs) is not radioactive. This seems to be a common confusion between "atomic" and "radioactive".
- tvb 6y agoLook for any vintage caesium clock made by National, Varian, Hewlett-Packard / Agilent / Symmetricom / Microsemi / Microchip, FEI, FTS / Austron / DATUM, Oscilloquartz, and maybe others. None of them are a restricted item because of a "radio-isotope". Again, cesium 133 is not a radioactive isotope. Atomic timekeeping is based on ultra-precise quantum mechanics, not random nuclear radioactive delay. Just take your time. Some of us look for months and even years before we find one worth the eBay risk. There is one fact to consider. I have heard that the 5071A clock is still ITAR classified. It's not because of "atomic" or "cesium", but because the internal design is so advanced that the US decided it was essentially like a military weapon. If in doubt look for vintage models like 5060, 5061, 5062, or 4050, 4060, 4065 instead of the still current model 5071.
- bjeds 6y agoPlease tell me more about your atomic clock. Which one did you eventually buy, how much did it cost, and how do you use it?
- tvb 6y agoAs a patient hobbyist collector I try to buy one of each. My goal was to learn the history and theory of each one, explore the magnificent design, measure the actual timing accuracy, read as many old books or articles about them, and in some cases meet the designers of the clocks. Atomic timekeeping, like computing, is a new enough field that a few of the old timers are still around. For the valley-mountain gravitational time dilation experiments that I've done I use 5071A cesium clocks. Even though 25+ years old, no commercial clock works better for this portable application. That is to say, rubidium clocks and older model cesium clocks are not quite good enough to detect these tiny relativistic effects with confidence. Others here have mentioned prices. Surplus rubidium atomic clocks can be found for as low as $100 on eBay. Surplus cesium clocks range from $1k to $10k, depending on model and condition. Factory new 5071A are close to $100k so no one I knows is crazy enough to do that. If you are very patient and lucky on eBay you will find 5071A for as low at $2k to $5k once every couple of years.
- Dirlewanger 6y agoDo these "atomic" clocks that get synched by an external ER source account for the (minute) travel time of said ER source? I'm assuming they do.
- xtiansimon 6y agoWolverine is your brother-in-law? Dude. You better be good to her.