Somewhat OT: Long term design
in [Design]
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From: JosephKK on 17 Jan 2010 15:56 On Sat, 16 Jan 2010 16:13:07 +1100, Sylvia Else <sylvia(a)not.at.this.address> wrote: >John Larkin wrote: >> On Fri, 15 Jan 2010 11:19:34 -0500, WangoTango >> <Asgard24(a)mindspring.com> wrote: >> >>> In article <hio9k9$fsu$1(a)news.albasani.net>, pNaonStpealmtje(a)yahoo.com >>> says... >>>> On a sunny day (Thu, 14 Jan 2010 17:54:31 -0500) it happened WangoTango >>>> <Asgard24(a)mindspring.com> wrote in >>>> <MPG.25b96ab48fc5c5b698ae28(a)news.east.earthlink.net>: >>>> >>>>> In article <035f8778$0$1309$c3e8da3(a)news.astraweb.com>, adrian(a)qq.vv.net >>>>> says... >>>>>> Maybe you could ask how far in the future you have to go before your >>>>>> 'device' becomes unrecognisable ? >>>>> What are you talking about? >>>>> I've watched TV and not only do those guys instantly recognize >>>>> millennium old devices, they recognize millennium old ALIEN devices, and >>>>> they all invariably function. I would be more interested in a power >>>>> source that could just sit for that period of time and still be useable, >>>> >>>> Solar. >>>> >>> Really....do we know what a solar cell will do after 1000yrs of sitting? >> >> Good cells are fairly klunky monocrystalline silicon PN junctions. >> They'd probably work fairly well after a million years if stored >> properly. >> > >This is where I wonder about difusion. Will those doping atoms stay put >over those sorts of time scales, or would we end up with a piece of >silicon pretty much equally doped throughout with both doping materials? > >Sylvia. They will stay put pretty well. Solid solubility at normal terrestrial surface temperatures is mighty low. Micron per hour diffusion requires about 2000K. And the mobility does follow the e^kt Arrhenious relationship.
From: Michael A. Terrell on 17 Jan 2010 16:50 JosephKK wrote: > > On Sat, 16 Jan 2010 08:05:00 -0500, "Michael A. Terrell" <mike.terrell(a)earthlink.net> wrote: > > > > >JosephKK wrote: > >> > >> Indeed, consider the traps in ancient tombs. > > > > > > The original 'lint' traps? ;-) > > I think they predated even 'lint' by quite a bit. ::)) You could ask Jim to settle it. ;-) -- Greed is the root of all eBay.
From: Nico Coesel on 17 Jan 2010 18:21 John Larkin <jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote: >On Sat, 16 Jan 2010 13:30:54 GMT, nico(a)puntnl.niks (Nico Coesel) >wrote: > >>"Tim Williams" <tmoranwms(a)charter.net> wrote: >> >>>"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. >> >>Tantalums are very prone to failure. I avoid them if I can. Even >>electrolytics are better because they don't cause a short. Nowadays I >>use the MLCC capacitors where I can. > >Tantalums are fine as long as their peak current (ie, dV/dT) is >limited. Of course, that makes them useless for most places you'd like >to use them. Lets say that I found too many defective tantalums in broken equipment. When it comes to capacitors: electrolytics come first, tantalums next. Besides that, a lot of rain forrest is cut to get the tantalum. -- Failure does not prove something is impossible, failure simply indicates you are not using the right tools... nico(a)nctdevpuntnl (punt=.) --------------------------------------------------------------
From: Uwe Hercksen on 29 Jan 2010 06:14 John Larkin schrieb: > You could cheat and store the gear in Antartica. Most degradation > mechanisms follow the Arrhenius relationship. Hello, you forgot the bad effect of temperature cycles at low temperatures between -60 and -10 �C. Low and constant temperatures would be better. Bye
From: Uwe Hercksen on 29 Jan 2010 06:20
Michael A. Terrell schrieb: > Tin whiskers. Hello, there is another problem with tin at low temperatures, it may transform into another modification, the solid metal will be a powder then. In german we call it Zinnpest or tin-plague. It has destroyed some organ pipes in churches during a very cold winter. It may be avoided by using a proper alloy of tin. Bye |