The 100 year clock - The beginning of a project  - Page 1
Forum section: electronics / projects

author: jazper
author_rank: Regular Contributor
timestamp: April 19, 2022, 03:05:59 am
content: After much thought I've decided to embark on a passion project, the 100 year clock.This will be an open source project and will be worked on as time permits.The objective is to have a functional working clock that is self powered for 100 years, that displays the current temperature in Celsius.There are two key challenges to overcome as I see them, battery/energy storage/generation tech (aka power), and display.Power wise I've started my research into using solar (think calculator solar cells) and using some kind of capacitor solution - either supercaps or ceramic capsDisplay tech wise I'm thinking e-ink display, potted in clear epoxy resin, refreshed every 2-5 minutes, as these can do 90 million refreshes or so before they cap out.I'd really appreciate any thoughts on these, including experiences or other advice about approaching this project.Thanks

author: TheMG
author_rank: Frequent Contributor
timestamp: April 19, 2022, 03:31:09 am
content: Quote from: jazper on April 19, 2022, 03:05:59 amA clock that doesn't refresh every minute would be rather annoying.I would go with an LCD display, then you don't have the issue of limited refresh lifespan. Power consumption is not much. When you think about it, a plain old digital wristwatch runs for several years on nothing more than a tiny button cell battery, so it's really not much energy at all.Should be doable with capacitors for storage (maintain clock operation during dark hours) and PV cell.

author: ataradov
author_rank: Super Contributor
timestamp: April 19, 2022, 03:45:20 am
content: LCDs don't last for 100 years though. Look at any old equipment, the LCDs are all dim and blurry. Modern LCDs may be better, of course, but I still don't think they will last this long.This is an interesting experiment, but it would be really hard to tell what would last. The least effort thing is to encase some casio wristwatch into epoxy and power it from the supercapacitors and a solar cell. Use reed switches for buttons, this way it could be completely encased. But that's not much of a project.And epoxy does not stay transparent forever either. Even the most clear epoxy becomes yellow in 3-5 years of normal storage. Storing it in the sun light would accelerate that process a lot.

author: Martian Tech
author_rank: Regular Contributor
timestamp: April 19, 2022, 03:52:17 am
content: Solar cells won't last 100 years either.

author: ledtester
author_rank: Super Contributor
timestamp: April 19, 2022, 04:02:40 am
content: If you want it to run continuously for 100 years make the display hot-pluggable so you (or one of your children/grandchildren) can replace it down the road. Also give it dual power supplies perhaps even redundant logic boards which can be hot-swapped out.

author: CatalinaWOW
author_rank: Super Contributor
timestamp: April 19, 2022, 04:03:24 am
content: I agree that you should aim for update of the display at "normal" intervals. 1, 5 or 10 minutes. 90 million cycles gives a theoretical life of 170+ years with one minute updates.You are really unlikely to be proven wrong on the life of your clock, but you will have to pay a lot of attention to component lifetimes to make the life credible. I would avoid LCD's, supercapacitors and any other component that depends on liquid chemistry, no matter how well sealed it is purported to be. Things like tin whiskers, corrosion and other similar problems will be an issue. The E ink displays seem vulnerable on this issue, which makes display choice a real issue. Lightly driven LEDs potentially have the life, but power consumption is an issue. Perhaps only have it come on for a couple of seconds once a minute. Potting in epoxy requires a lot of thought about what the outgassing products of the epoxy are and what their impact on other components is. UV susceptibility is also an issue.This is a worthy challenge, and probably should involve a lot of research into storage and operating life before even doing a conceptual design. NASA, ESA and various military organizations have done a fair amount of research on these issues, and with some digging quite a bit is accessible. Another source for first order ideas on the sorts of problems which occur can come from the repair/restoration threads on antique radios/test equipment. Although you are unlikely to use most of the technologies used in those old devices the problems can give you insight into what can go wrong.

author: Someone
author_rank: Super Contributor
timestamp: April 19, 2022, 04:15:45 am
content: https://en.wikipedia.org/wiki/Beverly_Clock+ thermometer?Electronic display technology just inst comparable, there is nothing with that sort of lifespan.

author: CatalinaWOW
author_rank: Super Contributor
timestamp: April 19, 2022, 04:36:27 am
content: Quote from: Someone on April 19, 2022, 04:15:45 amRead to Wiki on this clock. It hasn't run all this time, it has required cleaning, repair and has shut down because the temperature variations weren't sufficient to keep it wound.Mechanical devices have wear mechanisms also. But a mechanical display based on a dry jewel movement (lubricants all give up before 100 years) has some possibility of serving. A mechanical solution to the temperature display also would solve the power issues that come with an electronic solution.

author: Ed.Kloonk
author_rank: Super Contributor
timestamp: April 19, 2022, 04:37:15 am
content: I hope for the humanity's and the clock's sake we have converted to metric time (or something, anything!) by then.

author: jazper
author_rank: Regular Contributor
timestamp: April 19, 2022, 04:39:43 am
content: Quote from: Martian Tech on April 19, 2022, 03:52:17 amSolar cells on satellites have worked for 100 years, heck some amorphus(sp?) cells from calculators in the 70s are still going.https://www.digikey.com.au/en/products/detail/panasonic-bsg/AM-8801CAR-DGK-T/2165201Quote from: CatalinaWOW on April 19, 2022, 04:03:24 amThought about lightly driven LEDs - issue is the plastics involved (that will slowly gas off/degrade) - if driven lightly they'll probably get very dimQuote from: TheMG on April 19, 2022, 03:31:09 amDo you really need "to the minute" precision in everyday life?yah what capacitor tech?

author: Someone
author_rank: Super Contributor
timestamp: April 19, 2022, 04:45:25 am
content: Quote from: CatalinaWOW on April 19, 2022, 04:36:27 amThat example has not operated continuously, but better engineered with todays knowledge that basic concept should work on the 100 year time scale. One example as you say: jewel bearings are pretty routine now. Then there are the loonies trying for 10,000 years!

author: Someone
author_rank: Super Contributor
timestamp: April 19, 2022, 04:50:09 am
content: Quote from: jazper on April 19, 2022, 04:39:43 amFirst man made satellite, 1957:https://en.wikipedia.org/wiki/Sputnik_1Battery powered, no solar. You'd need to wait for 1958:https://en.wikipedia.org/wiki/Vanguard_1Are you a time traveler? or have you knowledge of some secret satellites predating the above?

author: jazper
author_rank: Regular Contributor
timestamp: April 19, 2022, 04:53:17 am
content: Quote from: Someone on April 19, 2022, 04:50:09 amhaha ok fair point

author: ejeffrey
author_rank: Super Contributor
timestamp: April 19, 2022, 05:12:41 am
content: A dry pile battery can run for over 100 years and should do so while providing enough current to run an electronic clock. Solar cells can also probably last that long, but then you need to make sure it gets regular light exposure. I wouldn't think you would want a clock that if put in a desk drawer for a month or a year would stop working.Accuracy is also a concern. 1 ppm * 100 years is almost an hour. Most lower power crystals have accuracy at best several few ppm over a small temperature range, not to mention aging over 100 years. Maybe you can carefully calibrate it after a year of burn-in and do temperature compensation but it's going to be really hard to get and keep it within 100 ppb which is pretty much required if you want it to be a *useful* clock after 100 years.Picking up radio time broadcasts or GPS would fix this but make your clock dependent on outside time sources, consume more power, and add a bunch of components that can fail over time.

author: BrianHG
author_rank: Super Contributor
timestamp: April 19, 2022, 05:14:34 am
content: LCD chemistry, electrode plating of the glass (look for a gold layer here), type of polarizers, sealing glue and plug, and means of electrical contacts have vastly improved since the earlier LCDs. This doesn't mean you may have purchased or selected a piece of junk which will die in 20 years, but, with wise selection, using clamped metal contacts (instead of elastomerit zebra connectors / glued flex cable connectors), and the addition of a UV filter ontop of the display, if you keep your temperatures under control, you should be able to achieve 100 year life with a minute-by-minute display update. But because of all the aforementioned above, there is still a gamble it can die in 20-50 years.(IE, I would look for glass polarizers used for photography lens instead of the cheap plastic.)As for your own processor, look here:https://www.eevblog.com/forum/projects/ultra-low-power-mcu-design-the-nanowatt-clock/Your best bet is to modify the existing code to activate the thermometer once every ~1 minutes for a short instant to take temperature readings to keep the power consumption as low as possible. But, you will still need to learn about the MCU and how to make sure your hardware programming wont waste power. You will also need to create an ultra low current measurement system to verify your power usage.See if you can find a battery guaranteed for 25-50 years. A 1000mah lithium coin cell should last ~200 year with the above clock. The 2x overkill is probably necessary as the battery will probably dry out.Do not waste your time with solar and any caps with dielectrics. Use ceramics caps only. Like only 10nf, over-voltage ones for the MCU power filtering.If you want to stay in the Sub-Nano-watt level of power the above clock runs on, to get the accuracy will be a problem if you aren't just using a crystal like in the reference design. Here I have no solutions unless you find a special crystal source or program correction LUT tables into the MCU.

author: jazper
author_rank: Regular Contributor
timestamp: April 19, 2022, 05:16:56 am
content: Quote from: ejeffrey on April 19, 2022, 05:12:41 am2ppm is possible with the maxim ds3231 (and like parts) using thermal compensation. Getting better than that is a challenge - I haven't found an RTC that can do that and still keep a low wattage. SiTime have some devices...

author: jazper
author_rank: Regular Contributor
timestamp: April 19, 2022, 05:24:39 am
content: Quote from: ejeffrey on April 19, 2022, 05:12:41 amIdeally therefore it'd be something that that can be charged, and hold charge for a time. I was thinking eneloop AA batteries to start with, they can go 15 years with minimal degradation and have quite some capacity, wouldn't want to overcharge them though.

author: jazper
author_rank: Regular Contributor
timestamp: April 19, 2022, 05:28:19 am
content: Quote from: BrianHG on April 19, 2022, 05:14:34 amThere is a 40 year battery with 19Ah. Self discharge is 0.7% per year.https://www.tadiranbat.com/long-life-xol.html<-- these will do 40 years, but I'm not sure that they will do longer, or other environmental variables. Is there something that could be done to reduce the chance of dry out? potting for instance?

author: BrianHG
author_rank: Super Contributor
timestamp: April 19, 2022, 05:42:57 am
content: Quote from: jazper on April 19, 2022, 05:28:19 amThe clock I linked to in the above post consumes 498na. Let's call that 0.5ua.With a 1ah 3v lithium cell, readily available, do the math:1 / 0.0000005 (current consumption) / 24 (hours in a day) / 365.25 (days in a year) = ~228 years.Now,, you come to me with a 19ah cell:19 / 0.0000005 (current consumption) / 24 (hours in a day) / 365.25 (days in a year) = ~4334 years.(I think you went off the deep end...)Anyways, the main thing to battery life is a constant temperature. Some batteries will fair better at slightly lower temperatures, ie 5-15 deg C while many will hate high temperatures like 85 deg C. Very cold just means it is hard to extract any meaningful power, but with 0.5ua, even a lithium at -20deg, especially a 1ah cell will still power your application.Potting may cause problems if the battery needs to slowly vent any gasses.

author: jazper
author_rank: Regular Contributor
timestamp: April 19, 2022, 05:50:52 am
content: Quote from: BrianHG on April 19, 2022, 05:42:57 amOh I wasn't suggesting power consumption would require 19ah.. The problem will be the self discharge. 0.7% per year, plus temperature variations. At the end of the 40 odd years, there many not be enough of the battery left (in terms of chemistry) to keep going much longer. see here:https://www.tadiranbat.com/assets/tl-4930-revf-0420.pdfOn the other hand with super caps:https://www.osti.gov/etdeweb/servlets/purl/20671677- suggests that 100 years may be possible

author: ejeffrey
author_rank: Super Contributor
timestamp: April 19, 2022, 05:52:47 am
content: Quote from: jazper on April 19, 2022, 05:16:56 amIt's also 5 ppm aging over 10 years. Aging can be partially predictable and corrected but not entirely and is not going to be corrected to a sub ppm level for any length of time.

author: jazper
author_rank: Regular Contributor
timestamp: April 19, 2022, 05:53:36 am
content: Quote from: ejeffrey on April 19, 2022, 05:52:47 amok, do you know of an alternative?

author: jazper
author_rank: Regular Contributor
timestamp: April 19, 2022, 06:14:43 am
content: Sitime have a 10ppb +- mems oscillator...SiT5501https://www.sitime.com/products/super-tcxos/sit5501- for example.. the problem is power consumption, these use order of magnitudes the power of what we have been talking

author: ejeffrey
author_rank: Super Contributor
timestamp: April 19, 2022, 06:25:12 am
content: Quote from: jazper on April 19, 2022, 05:53:36 amA sundial? </smartass>Basically no. I don't know of any oscillators with performance that would make an effective 100 year clock with a practical power envelope for a self powered device. Certainly not just going by the data sheet. Maybe you could figure out some way to make it work by careful and clever design but it would take years of experimenting to be confident in your design.Maybe look for a two oscillator solution? If you can show that the DS3231 can be calibrated stable for a few days maybe you can have a medium power more accurate oscillator that you start up periodically to calibrate the primary oscillator. You will have to make sure that the voltage and power fluctuations caused by starting up the high power oscillator will not affect the low power one to much otherwise you will be calibrating to the wrong point.

author: BrianHG
author_rank: Super Contributor
timestamp: April 19, 2022, 06:28:22 am
content: Depending on country, you can always tune into the local government time broadcast which some clocks in Europe use.You only need an SW am radio and Morris code decoder in your MCU. Such a radio circuit would consume something like 1ma when the MCU turns it on once a week or so.Tune in to verify and adjust the time once a week.Though, will the service still be available in 100 years as this old analog system has been around for decades and may soon be considered obsolete.Also, the nanowatt clock doesn't use the DS3231, it uses the MicroCrystal RV-3028-C7. Read it's data sheet for it's capabilities.

author: jazper
author_rank: Regular Contributor
timestamp: April 19, 2022, 06:38:43 am
content: http://www.technoblogy.com/show?19K8has shown up on my radar.. may be an alternative..I'll look into the dual osc solution soon, and yeah I've used the RV-3028-C7 before.

author: BrianHG
author_rank: Super Contributor
timestamp: April 19, 2022, 07:04:31 am
content: Quote from: jazper on April 19, 2022, 06:38:43 amThat clock consumes ~20x the power of the one I linked to here on EEVBlog.com.So, instead of 200 years, you will get 10 years.

author: jonpaul
author_rank: Super Contributor
timestamp: April 19, 2022, 09:00:22 am
content: Very old idea.See the mechanical of the Clock of the Long Now, 10,000 years....https://longnow.org/clock/no electronics will be reliable for 100 yearsMost displays have MTBF or 50 % dimming life,perhaps 5..15 yrsBon couragejon

author: emece67
author_rank: Frequent Contributor
timestamp: April 19, 2022, 09:22:38 am
content: .

author: jonpaul
author_rank: Super Contributor
timestamp: April 19, 2022, 11:57:02 am
content: Rebonjour à tousVisited Ft Mason San Francisco in 2008, clock of long now. Very impressive mechanical art.have Atmos Jaeger LeCoultre running since 1985, needs periodic service ,interval depending upon atmosphère pollution and dust.The ambient temperature variations power the mainspring and tortiion pendulum.Both Atmos and Long now shall continue to work after we are all turned to dust.I have 1960s nixie counters with DTL, TTL all having defects.Doubt if a modern design clock will be any more reliable with current cheap quality Chinese component manufacturer.Just the ramblings of an old retired EEJon

author: globoy
author_rank: Frequent Contributor
timestamp: April 19, 2022, 06:50:13 pm
content: I appreciate the idea of making something that will outlast us.When I was a kid, way back in 1980, I made a blinkie consisting of a 555 oscillator and 7490 decade counter driving 4 LEDs and encapsulated it in epoxy. Powered by a 6V transformer based linear power supply (7805), it's been running ever since. Interesting thing is that something in the oscillator has drifted and it's clocking about 3-4x faster that it did originally with the change seeming to be accelerating. It's been kept out of the sunlight and the resin is still very clear. When I made it I was fascinated by the idea of building electronics that once built could never be touched again (e.g. deep space probes) and this was my way of playing with that idea.

author: ledtester
author_rank: Super Contributor
timestamp: April 19, 2022, 07:43:15 pm
content: The battery powering the Oxford Electric Bell has been running for >176 years (as of 2016):The Battery That's Lasted 176 Years -- Tom Scotthttps://youtu.be/UtQGYz4f3YQSupposedly they are waiting for it completely deplete before they open it up and figure out how it was made.A more recent video (2019) says it is still running but the battery is so weak now that you can't hear the bell:The World's Longest Running Battery - and how to make your own. -- BBC Radio Oxfordhttps://youtu.be/YET_V0hhtYAIn 2014 someone created a replica and started it up:QuoteOxford Electrostatic Bell Replica closest thing to Perpetual Motion -- wekanduithttps://youtu.be/HNTbhOvu-2QMy guess is it's probably still running.

author: ejeffrey
author_rank: Super Contributor
timestamp: April 19, 2022, 07:45:19 pm
content: LED displays should be fairly long life, decades for sure if you keep the current low. We don't exactly have data for 100 years, but I bet they would do fine. One possibility would be to have a long life battery power the RTC, and a separate (solar? induction?) power supply for the display.I also like the idea of using an ambient light sensor and a PLL synced to the day/night cycle to keep the time accurate. An ordinary oscillator can keep time within an hour for several years. Just make sure to leave in a window for a few days every few years so that it can lock-on to solar time. As a bonus, if you move to another timezone it can auto adjust to local solar time.

author: metrologist
author_rank: Super Contributor
timestamp: April 19, 2022, 07:55:47 pm
content: Cool! I'm thinking Sundial and Galileo thermometer.

author: free_electron
author_rank: Super Contributor
timestamp: April 19, 2022, 08:16:08 pm
content: 100 years.. pah ! try the clock of the long now.https://en.wikipedia.org/wiki/Clock_of_the_Long_Now

author: Gyro
author_rank: Super Contributor
timestamp: April 19, 2022, 08:27:24 pm
content: Quote from: ejeffrey on April 19, 2022, 07:45:19 pmIt used to be easy to find HP Hermetic LED displays, not these days though.Counter intuitively, Minitron 3015F filament displays (petrol pump type), are / were rated for 50k hours @5V. De-rate them by 20% or more and you would probably achieve phenomenal life, even if rather dim. I don't ever remember seeing one with a broken segment, even though they were probably driven pretty hard for outdoor daylight. Just don't drop them!

author: jazper
author_rank: Regular Contributor
timestamp: April 19, 2022, 08:46:37 pm
content: One thought I had was to use common rechargables (eg eneloop) and have a charging tray integrated. The thing is that I can't guarantee is that AAs will be around 100 years from now

author: viperidae
author_rank: Frequent Contributor
timestamp: April 20, 2022, 01:21:41 am
content: What's going to run the clock? I wasn't aware the flash memory of a microcontroller would last that long, so maybe a maskrom device or discrete logic?

author: MikeK
author_rank: Super Contributor
timestamp: April 20, 2022, 01:58:46 am
content: Quote from: viperidae on April 20, 2022, 01:21:41 amI have an EEPROM chip from STMicroelectronics that says "More than 200-year data retention" in the datasheet.

author: cdev
author_rank: Super Contributor
timestamp: April 20, 2022, 02:11:40 am
content: Underpowered LED dot matrix displays running at a fraction of design brightness would likely last hundreds of years and run on 5ma or less.

author: LaserSteve
author_rank: Super Contributor
timestamp: April 20, 2022, 04:42:09 am
content: Large vacuum photodiodes made to AT&T or BT undersea cable tube standards could give you a few hundred uA from sunlight. The beauty is that odds of them failing shorted are nil. There is a company that makes beta source batteries for this sort of thing. UV resistant borosilicate glass with hard seals could easily give you a power boost for 50 years or more.I would bet that many of the old tube based repeaters on the ocean floor would come right back into service if carefully powered up.Steve

author: emece67
author_rank: Frequent Contributor
timestamp: April 20, 2022, 08:59:07 am
content: .

author: richard.cs
author_rank: Super Contributor
timestamp: April 20, 2022, 09:14:02 am
content: Quote from: ejeffrey on April 19, 2022, 06:25:12 amThe streetlights around here have solar-synchronised clocks to turn them off at 1 am, and along a street they switch almost simultaneously with one another (within a few hundred milliseconds). It's pretty impressive, I thought it was radio-commanded at first. As I understand it they track the dawn and dusk times (maximum rate of change of sunlight) with a cheap watch crystal that runs 24/7, take the midpoint, and add an hour. It works surprisingly well, I am not sure how many days it averages over.

author: jazper
author_rank: Regular Contributor
timestamp: April 20, 2022, 10:48:59 am
content: what about gps syncing in once a month to trim it?

author: BrianHG
author_rank: Super Contributor
timestamp: April 20, 2022, 11:03:02 am
content: Quote from: jazper on April 20, 2022, 10:48:59 amHow do you know it will still be available or compatible with existing receivers in 100 years?You can always make a tuned 50/60hz receiver and PLL lock to the grid as your reference.Actually, with the 500na clock, you might be able to harvest power from your AC antenna to keep a supercap charged.

author: jazper
author_rank: Regular Contributor
timestamp: April 20, 2022, 11:12:17 am
content: I don't..Quote from: BrianHG on April 20, 2022, 11:03:02 amI don't.. with 500na, you could (in theory) use ambient wifi/radio etc signals I spose

author: Gyro
author_rank: Super Contributor
timestamp: April 20, 2022, 11:12:29 am
content: Quote from: BrianHG on April 20, 2022, 11:03:02 amHow do you know that the grid won't be DC in 100 years?

author: BrianHG
author_rank: Super Contributor
timestamp: April 20, 2022, 08:19:55 pm
content: Quote from: Gyro on April 20, 2022, 11:12:29 amLocally, the infrastructure change to DC will be too expensive. Large distance transmission is going HVDC, but for local neighborhood distribution, large scale transformers is still king and too many expensive appliances and infrastructure relies on AC. Just look at an office building. Do you think they will re-wire every switch, change all the elevators, all the lighting ballasts, every LED bulb with uses caps as a DC voltage dropper. You would need a new city from scratch, 0 building and infrastructure to go to DC. And that city will not be able to purchase any existing hardware because of possible incompatibility concerns. Everything will need to have guaranteed special DC support.

author: Gyro
author_rank: Super Contributor
timestamp: April 20, 2022, 09:24:10 pm
content: True right now, but 50 years ago, who'd have though that efficient long distance HVDC interconnects and associated semiconductors would be possible. Large lumps of iron are disappearing everywhere and that transition will only accelerate. Capacitive droppers are a major source of unreliability and premature post warranty failure. Motors are all going semiconductor commutated brushless. Philips high efficiency LED lamps are already going buck...https://www.eevblog.com/forum/chat/the-dubai-lamp/msg4126000/#msg4126000(bottom of page)

author: CatalinaWOW
author_rank: Super Contributor
timestamp: April 20, 2022, 10:10:33 pm
content: I think the installed base will make a switch to DC a very slow occurrence. Installed base is the biggest single reason for the slow US conversion to metric.

author: Gyro
author_rank: Super Contributor
timestamp: April 20, 2022, 10:24:06 pm
content: 100 years is still100 years!. That's a hell of a long time in technological terms. As for the metric thing, I don't know. We managed it, but that's what the thread is about. I still wouldn't rely on 50/60Hz network for timing purposes any more than I would current gps over that timeframe.

author: jazper
author_rank: Regular Contributor
timestamp: April 20, 2022, 11:42:33 pm
content: Atmel rates their flash memory on their microcontrollers to 100 years, an automotive grade one run in normal temperatures should reach that.

author: jazper
author_rank: Regular Contributor
timestamp: April 20, 2022, 11:58:33 pm
content: Ok so we've ascertained:LCDs may work for the duration, if underdriven and of sufficient qualityMicrocontrollers are likely to reach the duration without too much dramaPower supply is still a concern, haven't settled on anything yet, solar still seems like the best (overrated amorphous solar cells with diodes to prevent drain) , looking at the potential for graphene supercaps, some solid state rechargeable lithiums exist with 300~ cycles but lifetime unknown - 350F supercap should run a 400nA device for about 100 days (after voltage conversion and significant aging of its electrolyte etc)Timing is a concern, GPS may not be around 50 years from now in its current form, one thought is that it keeps trying to acquire a signal once a month, or once every other month and when it stops doing that for a number of tries, it calculates the amount of drift in the oscillator then keeps adjusting it moving forward.Re Power supply- Tadiran has 20 year 20000 partial cycle rated industrial lithium batteries in AA formathttps://www.tadiranbat.com/tli-rechargable.html- Tadiran also has 40 year rated primaries- Eaton 350F supercaps (if run at 2.4-2.5v) are good for 100,000s of cycles, but unknown how long the electrolyte will last- Nuclear (beta voltaics) - very difficult to get a hold of unless you're talking tritium, and tritium is only good for 20-30 years. Also very expensive ($1500+)- NiMh chemistry is no good for slow incremental charge, due to memory effects, will probably die in 10 year range- LTO chemistry is good for 7000-10,000 cycles, however unsure of how long the electrolyte will last.- Gold nanowire batteries with polymer gel electrolyte are good for 200,000 cycles, but experimental at this point (difficult to get outside of a lab, and presumably very expensive)Re timing:- Currently the rtc (RV-3028-C7) mentioned inhttps://www.eevblog.com/forum/projects/ultra-low-power-mcu-design-the-nanowatt-clock/seems to be the best option but it will age +-3ppm during the first year- GPS may be a temporary inexpensive solution for the next 30-50 years to trim the clock, unknown after that- nuclear decay clocks (rubidium) are expensive at $1k USD, but in stock at various vendors, their power requirements are however very high, comparatively speaking.

author: ale500
author_rank: Frequent Contributor
timestamp: April 21, 2022, 08:51:24 am
content: These atmos clocks work using difference in pressure and temperature to generate the needed force, maybe this proven concept, in terms of longevity, could help if somehow it could be used to provide some electricity. I think that simplicity is something you may search for longevity. Electronics from the 70s and 80s are failing, at least consumer. The Voyagers are still going strong but they are at another level of reliability by design. That is something that the people of the long now have been developing for. There are several different pieces here, the display is just one of them. I'd start with the power source, I love power supplies. Best luck !

author: jazper
author_rank: Regular Contributor
timestamp: April 21, 2022, 11:14:07 am
content: Quote from: ale500 on April 21, 2022, 08:51:24 amThe main thing that fails from the 70s/80s is capacitors .. the rest seems to keep going

author: cdev
author_rank: Super Contributor
timestamp: May 07, 2022, 11:03:46 pm
content: What happens after the 100th year ends? What is the purpose, what scenario is it supposed to address? Why do we need it? Are we going to become unstuck in time? Coronavirus i seems has done this. As peoples lives increase in duration, 100 years will shorten as perceived. It starts out as an extremely long time, longer than most lives, I doubt it it will remain that way. Right now the best predictor of your lifespan may be SES or your socioeconomic status.Since time doesn't stop, we still have to keep things going. Arbitrary time limits often cause problems, I think.Soon you will likely be able to use rectified RF from the environment for power..(a modest amount) in most places. Maybe thats possible already.Many people live to be over 100 and some live to over 120.We dont know why people age as they do now. But we likely will soon.Quote from: jazper on April 19, 2022, 03:05:59 am(and knowing exactly what day, hour , second, etc. independently. GPS may not always be available. What if it changes? SVs age out and others age in?The new ones may not be compatible? But will there be continuity? I have a GPS that no longer works, its firmware has got an issue. It can be wrked around, but one has to know specifics. What changed. Its probably fixable. With an updated firmware blob.Quote from: jazper on April 19, 2022, 03:05:59 amLCDs take almost no power! They can run forever off a tiny battery, or out of the air RF. Yes, that little power..If you are near a city, thats probably enough..If the transmitters stay on.

author: BrianHG
author_rank: Super Contributor
timestamp: May 08, 2022, 12:37:05 am
content: An alternative to LCD with proper design will be guaranteed to last 100 years would be a miniature flip-dot display. Replicating a 7 segment display, flipping the dost only once every minute will still consume more than a LCD, but, since you use 0 current except during the flip action, smartly pulsing only the needed change elements means only a ~3 segment changes per minute with ~6 on every tenth minute. Though, a super tiny flip-dos display would be a custom build. You would need to get the mechanics and electro-magnets just right to consume the absolute minimum power to flip a segment. Do not judge the power consumption of the huge bill-board style flip-dot displays unless you need a clock with a gigantic display. Then, LCD will still consume less at such large sizes.

author: CatalinaWOW
author_rank: Super Contributor
timestamp: May 08, 2022, 01:27:27 am
content: Quote from: cdev on May 07, 2022, 11:03:46 pmMany people live to over 100. True, but most estimates say that roughly half a million people over the age of 100 are living today. With eight billion people on earth that means that roughly one in sixteen thousand people makes it to 100. Hardly a statistic that projects to everyone expecting to live to over 100. The stats at 120 are far worse.Perhaps after solving the problems of lasting 100 years it will be good project on your 100th birthday to extend the life of the clock.

author: cdev
author_rank: Super Contributor
timestamp: May 08, 2022, 02:40:34 am
content: Its an interesting test... You can make components last a long time...But.. planned obsolescence.. The permanent money train.. They will still demand you replace them. Software update! will make the old hardware die.. like my GPS. "Youre not supposed to keep them very long" I was told..But..what if I want to? Tough luck.. I replaced the batteries for nothing.. it doesnt work at all now.Mandatory software as a service?

author: ejeffrey
author_rank: Super Contributor
timestamp: May 08, 2022, 03:16:21 am
content: Quote from: jazper on April 20, 2022, 11:58:33 pmRubidium clocks are very accurate but they don't last that long. They have a discharge lamp with a limited lifetime.

author: cdev
author_rank: Super Contributor
timestamp: May 08, 2022, 12:49:47 pm
content: Where do we have permanent power? The new 5G network.. One could make small computers and radio transceivers that never turned off that were always online.No more recharging batteries. No more unplugging from the network.This is one change that bothers me. I am sure this will be misused. What to do? Nuke everything suspect of carrying these RFID chips in the microwave to fry them?Put up with being always online? No, neither is likely to be that helpful.

author: cdev
author_rank: Super Contributor
timestamp: May 08, 2022, 01:04:31 pm
content: They are like a latching display..And you imply flipping the dot takes almost no power..I can see that. But it has to remain updated . What if it forgets the present time for some reason.. maybe being stored upside down. or powered off.. 100 yrs is a long time..Quote from: BrianHG on May 08, 2022, 12:37:05 am

author: vincemulhollon
author_rank: Newbie
timestamp: May 09, 2022, 02:30:30 pm
content: A moving coil analog microammeter can operate for quite a few cycles, I imagine 100 years of a row of them displaying each digit of the time would be quite appealing.Its pretty easy to make mechanical things that operate 100+ years (see mechanical watches) and pretty easy to make magnets that have a constant field for more than a century.It drives people crazy sometimes that a 100 uA micrometer will never draw more than 100 uA to display full scale and its theoretically useful even if it only displays five seconds every minute or whatever. Note that a GOOD constant current source will not care what the voltage is as long as it can push 100 uA thru the meter coil.True, in the old days natural animal oils with double bonds were used to oil watches and as such the oil would polymerize in 25+ years so mechanical watches required service every couple decades, but those days are long over and far superior non-polymerizing non-corrosive fully synthetic lubricants have existed for some decades. A row of analog meters should be quite reliable for a mere century.True, the cheapest lowest quality permags used to lose field strength over the decades, but better stuff is theoretically available now. I suppose its "cheating" to add a calibration pot for each dial?