Somewhat OT: Long term design
in [Design]
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From: Jim Thompson on 14 Jan 2010 09:39 On Wed, 13 Jan 2010 20:41:48 -0800, Joerg <invalid(a)invalid.invalid> 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. It's all about maintenance. Wonder how often the bellows had to be replaced/rebuilt? Probably even some pipes? ...Jim Thompson -- | James E.Thompson, CTO | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona 85048 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | I love to cook with wine. Sometimes I even put it in the food.
From: John Larkin on 14 Jan 2010 10:11 On Fri, 15 Jan 2010 00:28:54 +1100, Sylvia Else <sylvia(a)not.at.this.address> wrote: >John Larkin wrote: >> On Thu, 14 Jan 2010 19:21:43 +1100, Sylvia Else >> <sylvia(a)not.at.this.address> wrote: >> >>> a7yvm109gf5d1(a)netzero.com wrote: >>> >>>> OR.... >>>> >>>> go all mechanical >>>> >>>> http://www.longnow.org/ >>>> >>>> (How long does a weight suspended in the air keeps its potential >>>> energy? Makes a good battery, no?) >>> Yes.... >>> >>> But now you have to design a mechanism to extract the energy that will >>> work after 1000 years. >>> >>> Sylvia. >> >> Centuries-old weight-powered clocks still work. Surely we can do >> better with modern materials. >> >> I don't think 1000 years is a long time for good materials. > >OK, you're just convincing me I should have said 10,000 years ;) > >Or indeed, the 48,000 years in the TV program. > >Though in Stargate Atlantis, they do have the advantage of using >"naquita" (sp?) for their power source, which seems to be an element >oddly overlooked in the periodic table. > I think it's a cheap brand of tequila. John
From: Tim Williams on 14 Jan 2010 10:40 "Bit Farmer" <bit.farmer(a)yahoo.com> wrote in message news:mfKdnZOAz8yitNLWnZ2dnUVZ_h9i4p2d(a)giganews.com... >> 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? > > You just put them on the outside of the Space Ship. That way you would > never lose the vacuum. Not quite -- interplanetary space is around 10^-6 torr IIRC, which is good enough for crappy triodes, but you won't get a 6L6 working quite well enough out there. There's also a mixture of gas and particles which would be better removed with a getter than the electrodes. A solar powered diffusion pump (wait, do diffusion pumps work without gravity?) would be a low maintenance solution. Tim -- Deep Friar: a very philosophical monk. Website: http://webpages.charter.net/dawill/tmoranwms
From: Bill Sloman on 14 Jan 2010 11:08 On Jan 14, 4:40 pm, "Tim Williams" <tmoran...(a)charter.net> wrote: > "Bit Farmer" <bit.far...(a)yahoo.com> wrote in message > > news:mfKdnZOAz8yitNLWnZ2dnUVZ_h9i4p2d(a)giganews.com... > > >> 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? > > > You just put them on the outside of the Space Ship. That way you would > > never lose the vacuum. > > Not quite -- interplanetary space is around 10^-6 torr IIRC, which is good > enough for crappy triodes, but you won't get a 6L6 working quite well enough > out there. There's also a mixture of gas and particles which would be > better removed with a getter than the electrodes. A solar powered diffusion > pump (wait, do diffusion pumps work without gravity?) would be a low > maintenance solution. A turbo-molecular pump would do the job. It needs a power source to keep the rotor spinning, and you'd need non-contact (magnetic bearings) to keep it spinning for a thousand years with vibration isolation to prevent micrometeoroid impacts from shaking the rotor (a decent gyroscope) into the bearing housing from time to time. -- Bill Sloman, Nijmegen
From: WangoTango on 14 Jan 2010 11:28
In article <7r7lkiF174U1(a)mid.individual.net>, invalid(a)invalid.invalid says... > > 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. Ah, but that is with constant, or at least intermittent, use and maintenance. Let that drill or pipe organ sit for 100 years and see how well they work. |