Somewhat OT: Long term design
in [Design]
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From: John Larkin on 14 Jan 2010 00:45 On Wed, 13 Jan 2010 21:30:33 -0800 (PST), a7yvm109gf5d1(a)netzero.com wrote: >On Jan 13, 9:31 pm, Sylvia Else <syl...(a)not.at.this.address> wrote: >> A recent episode of Stargate Atlantis prompted me to think about how >> would could design equipment that's intended to function far into the >> future. The episode required stuff to function 48,000 years after >> construction, but perhaps we could be less optimistic. >> >> Say 1000 years. >> >> Note, the requirement is not that the equipment function *for* 1000 >> years, but that when it is turned on, 1000 years from now, that it will >> work. >> >> It seems to me that semiconductors are out due to effects of difusion >> and radiation. >> >> But how about thermionic valves? They're not very reliable, but do they >> age when not in use? Would they hold a vacuum over that time? > >Oh, they can be made very reliable. They can be accelerated at 100Gs >and used in proximity fuzes (note the spelling), as in WWII; 20,000 Gs! John
From: a7yvm109gf5d1 on 14 Jan 2010 00:48 On Jan 14, 12:41 am, John Larkin <jjlar...(a)highNOTlandTHIStechnologyPART.com> wrote: > On Wed, 13 Jan 2010 21:20:58 -0800, Robert Baer > > <robertb...(a)localnet.com> wrote: > >> I'd expect that most semiconductors and passives would last 1000 > >> years, given a conservative design. There's not much radiation around > >> at sea level. The gadget could be stored in vacuum or dry nitrogen to > >> prevent corrosion and wiskers and such. > >* Sorry, NASA has seen whisker growth in their satellites.. > > Well, you'd have to do whatever works best. Leaded solder comes to > mind! > > John What about 1960s-style welded flatpacks? No solder at all!
From: Tim Williams on 14 Jan 2010 00:50 "John Larkin" <jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote in message news:3mbtk55eiaskjbllse9ceknp3lblra9tal(a)4ax.com... > Aluminums fail by drying out, through water vapor leakage through the > rubber seals. That's a wearout mechanism. Al Po's? Generally considered as good as tantalum and fairly indestructible, aren't they? Kind of new to use for millenium hardware though. Tim -- Deep Friar: a very philosophical monk. Website: http://webpages.charter.net/dawill/tmoranwms
From: John Larkin on 14 Jan 2010 00:52 On Thu, 14 Jan 2010 15:51:25 +1100, Sylvia Else <sylvia(a)not.at.this.address> wrote: >Joerg wrote: >> John Larkin wrote: >>> On Thu, 14 Jan 2010 13:31:08 +1100, Sylvia Else >>> <sylvia(a)not.at.this.address> wrote: >>> >>>> A recent episode of Stargate Atlantis prompted me to think about how >>>> would could design equipment that's intended to function far into the >>>> future. The episode required stuff to function 48,000 years after >>>> construction, but perhaps we could be less optimistic. >>>> >>>> Say 1000 years. >>>> >>>> Note, the requirement is not that the equipment function *for* 1000 >>>> years, but that when it is turned on, 1000 years from now, that it >>>> will work. >>>> >>>> It seems to me that semiconductors are out due to effects of difusion >>>> and radiation. >>>> >>>> But how about thermionic valves? They're not very reliable, but do >>>> they age when not in use? Would they hold a vacuum over that time? >>>> >>>> Obviously electrolytic capacitors are a no-no, but can resistors and >>>> capacitors be made stable enough that they'd work? >>>> >>>> Would it help to enclose the entire circuit in a vacuum tube? Again, >>>> could the tube sustain the vacuum over such a period? >>>> >>>> An energy source is a problem. Perhaps a cell where acid is added >>>> (how?) at the appropriate time? >>>> >>>> Sylvia. >>> >>> I'd expect that most semiconductors and passives would last 1000 >>> years, given a conservative design. There's not much radiation around >>> at sea level. The gadget could be stored in vacuum or dry nitrogen to >>> prevent corrosion and wiskers and such. >>> >>> It shouldn't be hard to keep a vacuum tight for 1000 years. A decent >>> flange-sealed vacuum vessel hardly leaks at all. If it can do 1e-12 >>> torr for a minute, it leaks to atmosphere in (linear extrapolation) 2 >>> billion years. >>> >>> I think solar cells would stand up well. I bet that a Casio solar >>> calculator will work 1000 years from now if properly stored. The >>> biggest hazard would probably be polymerization of the plastics in the >>> keypad, or maybe leakage from a poorly sealed LCD. >>> >>> I still use my original HP35 calculator, purchased in 1972. >>> >> >> HP11C over here. I still use my grandpa's drill from around the 1920's. >> Works fine. You just have to keep the grease reservoirs packed by >> tightening the caps once in a while and refilling when at the peg. >> >> Oh, and the church we were married at goes back about 1200 years, the >> organ in there is probably well past 500 years. I guess a pipe organ >> fulfills the definition of "equipment". It can be done. >> > >Well, I'm not sure the organ qualifies, even if it reaches 1000 years. >Has it never been repaired? > >The requirement is that the equipment be built, be left untouched for >1000 years, and then work. > >Sylvia. Reliability folks generally assign component failure rates in FITs, namely one failure per billion hours. Most passives have numbers near 1 FIT, and lots of semiconductors are in the single digits. So a 100-part gadget that uses average 1 FIT parts will have an MTBF of 1e7 hours, a bit over 1000 years. That assumes the parts have no wearout mechanism. In practise, field failure rates can be quite a bit better than specs like MIL-HBK-217 or Bellcore predict, ie better than 1 FIT average per part. John
From: a7yvm109gf5d1 on 14 Jan 2010 00:54
On Jan 14, 12:45 am, John Larkin <jjlar...(a)highNOTlandTHIStechnologyPART.com> wrote: > On Wed, 13 Jan 2010 21:30:33 -0800 (PST), a7yvm109gf...(a)netzero.com > wrote: > > > > >On Jan 13, 9:31 pm, Sylvia Else <syl...(a)not.at.this.address> wrote: > >> A recent episode of Stargate Atlantis prompted me to think about how > >> would could design equipment that's intended to function far into the > >> future. The episode required stuff to function 48,000 years after > >> construction, but perhaps we could be less optimistic. > > >> Say 1000 years. > > >> Note, the requirement is not that the equipment function *for* 1000 > >> years, but that when it is turned on, 1000 years from now, that it will > >> work. > > >> It seems to me that semiconductors are out due to effects of difusion > >> and radiation. > > >> But how about thermionic valves? They're not very reliable, but do they > >> age when not in use? Would they hold a vacuum over that time? > > >Oh, they can be made very reliable. They can be accelerated at 100Gs > >and used in proximity fuzes (note the spelling), as in WWII; > > 20,000 Gs! > > John Yeah, even worse! I was probably thinking of this toy http://www.youtube.com/watch?v=nLpLEgAS574&feature=related I guess an artillery shell leaves in even bigger of a hurry, but doesn't *keep* accelerating... More of a "jerk" situation? |