Somewhat OT: Long term design
in [Design]
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From: krw on 16 Jan 2010 13:59 On Sat, 16 Jan 2010 17:12:54 GMT, Jan Panteltje <pNaonStpealmtje(a)yahoo.com> wrote: >On a sunny day (Sat, 16 Jan 2010 12:02:26 -0500) it happened Spehro Pefhany ><speffSNIP(a)interlogDOTyou.knowwhat> wrote in ><g8s3l5lah5gm8n12mlrsnvj1eq0v6jfcef(a)4ax.com>: > >>On Sat, 16 Jan 2010 14:09:08 GMT, the renowned Jan Panteltje >><pNaonStpealmtje(a)yahoo.com> wrote: >> >>>(Nico Coesel) wrote in <4b51bf27.575498125(a)news.planet.nl>: >>> >>>>Tantalums are very prone to failure. >>> >>>Not if you use them right >> >>Wot mostly consists of leaving them safely on the reel. ;-) >Well, then they still may fail ;-) >Just that you won't know about it. s/know/care/ >But on the more serious side, I have never had one go kaput, I certainly have. We have a huge fallout on 220uF 35V tantalums; right off the reel. They're better than aluminums, though. The aluminums didn't make it through the RoHS process. :-( >I like them because of low ESR and small size. >They do not dry out, some have been on for 20 years... Some light bulbs have made it 50 years, others have cause somewhat more problems. >I have seen exploded ones cause damage in equipment, most likely because they were put in in reverse... >I put one in (actually a whole series) in reverse myself one day, because the + was marked with a big -- >That came out when the first one was tested, and the resistor in series with it burned a hole in the PCB. >That was supposed to be a fusible resistor, I have now learned that metal film resistors do not fuse very well. That too. Even ones inserted the right direction tend to short, taking out the series resistor. We're seeing a lot of charred resistors next to those 220uF caps. Many years ago, it we found that no matter what we did, 1% got inserted backwards. ...even if the manufacturer had to put them in the tube backwards to meet the target. ;-) The solution was a fuse in the cap, non-polarized cases (+-+ or +--+ pinouts), or big/little pin, though the latter still could be force fit.
From: Phil Hobbs on 16 Jan 2010 14:39 On 1/15/2010 12:09 PM, John Larkin wrote: > On Fri, 15 Jan 2010 11:21:55 -0500, WangoTango > <Asgard24(a)mindspring.com> wrote: > >> In article<dwO3n.72802$IU1.46830(a)en-nntp-04.dc1.easynews.com>, >> zapwireDASHgroups(a)yahoo.com says... >>> "WangoTango"<Asgard24(a)mindspring.com> wrote in message >>> news:MPG.25b96ab48fc5c5b698ae28(a)news.east.earthlink.net... >>>> 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've always been most impressed with how readily humans seem to be able to >>> pick up on how to run, e.g., an entire alien spacecraft despite said aliens >>> not speaking any known language, not necessarily resembling human >>> physiologically (e.g., the wavelengths you use in displays is going to be >>> tuned to the individual species), and of course so often coming from planets >>> with gravities and atmospheres highly compatible with human life. :-) >>> >>> >> Yeah, funny how they never 'beam' over to a 5G engineering room. >> Or a 0G and float away. >> >> The problem with aliens is that they are alien. >> > > The stupid TV shows just need villains to add drama. All the aliens > that I've met were actually very nice. > > John > Speaking as a resident alien, most of the ones I know are OK in small doses. ;) Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal ElectroOptical Innovations 55 Orchard Rd Briarcliff Manor NY 10510 845-480-2058 email: hobbs at electrooptical dot net http://electrooptical.net
From: Tim Williams on 16 Jan 2010 14:52 They'll pretty well stay put. Diffusion is an exponential thing, so where it's happening at say 800K, it's down by exp(800K/300K) = 14.4 times at room temperature. Wait, that's not so impressive. References.... ah, diffusion follows the Arrhenius equation, which puts it in terms of exp(Eo/k_B*T), so the ratio between temperatures is exp(-(Eo/k_B*T) * (1/T1 - 1/T2)). That requires knowing what the activation energy is, though. Can't find it. Tim -- Deep Friar: a very philosophical monk. Website: http://webpages.charter.net/dawill/tmoranwms "Sylvia Else" <sylvia(a)not.at.this.address> wrote in message news:00ff5f63$0$27810$c3e8da3(a)news.astraweb.com... > 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.
From: Michael A. Terrell on 16 Jan 2010 17:58 Phil Hobbs wrote: > > On 1/15/2010 12:09 PM, John Larkin wrote: > > On Fri, 15 Jan 2010 11:21:55 -0500, WangoTango > > <Asgard24(a)mindspring.com> wrote: > > > >> In article<dwO3n.72802$IU1.46830(a)en-nntp-04.dc1.easynews.com>, > >> zapwireDASHgroups(a)yahoo.com says... > >>> "WangoTango"<Asgard24(a)mindspring.com> wrote in message > >>> news:MPG.25b96ab48fc5c5b698ae28(a)news.east.earthlink.net... > >>>> 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've always been most impressed with how readily humans seem to be able to > >>> pick up on how to run, e.g., an entire alien spacecraft despite said aliens > >>> not speaking any known language, not necessarily resembling human > >>> physiologically (e.g., the wavelengths you use in displays is going to be > >>> tuned to the individual species), and of course so often coming from planets > >>> with gravities and atmospheres highly compatible with human life. :-) > >>> > >>> > >> Yeah, funny how they never 'beam' over to a 5G engineering room. > >> Or a 0G and float away. > >> > >> The problem with aliens is that they are alien. > >> > > > > The stupid TV shows just need villains to add drama. All the aliens > > that I've met were actually very nice. > > > > John > > > > Speaking as a resident alien, most of the ones I know are OK in small > doses. ;) How small of a dose, and is it contagious? ;-) -- Greed is the root of all eBay.
From: JosephKK on 17 Jan 2010 15:25
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. ::)) |