Cruise ship stuck in ice
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From: Spehro Pefhany on 6 Mar 2010 16:28 On Sat, 6 Mar 2010 23:00:26 +0200 (EET), the renowned Okkim Atnarivik <Okkim.Atnarivik(a)twentyfour.fi.invalid> wrote: >Paul Keinanen <keinanen(a)sci.fi> wrote: >: In order to keep this discussion on topic, why is it so hard to get >: component specifications from semiconductor manufacturers for >: temperatures below 0 C ? > > Actually, more and more modern CMOS semiconductors seem to work even >at 4.2K . More so than, say, 15 years ago. My wild guess is that >linewidth reduction combined with higher switching speed requirements >have driven the manufacturers to use heavier doping levels, attempting >to get higher mobility. A side effect is that the carriers no longer >freeze out. > > Regards, > Mikko I thought it was primarily bipolar that had problems with 4K (including such weirdities as Si diodes oscillating. Do you have/would you be willing to share a list of parts that have been found to work at liquid He temperatures? Best regards, Spehro Pefhany -- "it's the network..." "The Journey is the reward" speff(a)interlog.com Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com
From: Royston Vasey on 7 Mar 2010 02:47 "Paul Keinanen" <keinanen(a)sci.fi> wrote in message news:3495p59tnqi5rtlcg2r7fb3dnghuv0rku0(a)4ax.com... > On Sat, 6 Mar 2010 14:34:00 +0200 (EET), Okkim Atnarivik > <Okkim.Atnarivik(a)twentyfour.fi.invalid> wrote: > >>Paul Keinanen <keinanen(a)sci.fi> wrote: > >>: Apparently due to the warmingist propaganda, the railroad network in >>: Finland is stuck, when there are cold temperatures or some snow and >>: trains are hours late, while in the Saint Petersburg region in Russia >>: (just 200-400 km East from here) such climate conditions do not cause >>: problem for the traffic. >> >> I agree that probably expectations of warmer and warmer winters has >>kept the VR railroad company from investing in snow-tolerant equipment. >>Now they are taken by surprise by this downswing in temperature. Still, >>I think the cold winter here is just an anecdote - not saying much >>about the global average temperature, and even less about what the >>long-term trend actually is. The artficially warm recent winters (in >>particular 07-08) have felt really creepy. >> >> Regards, >> Mikko > > In order to keep this discussion on topic, why is it so hard to get > component specifications from semiconductor manufacturers for > temperatures below 0 C ? > > I mostly work for a company that ships products all over the world > (including Siberia) and we have to test the equipment shipped at low > temperatures in order to avoid using military priced components for > ordinary industrial applications. > > In practice, most problems at low temperature systems are associated > with getting oscillators to oscillate at low temperatures. > And from a hardware testing POV - what do others do to test sub zero (Celcius) without a proper humidity controlled envirochamber? In the past I had fun testing some gear down to about -10C with condensation on the board creating havoc. In the end we placed the boards in a sealed box with some dessicant.
From: Okkim Atnarivik on 7 Mar 2010 11:12 Spehro Pefhany <speffSNIP(a)interlogdotyou.knowwhat> wrote: : I thought it was primarily bipolar that had problems with 4K : (including such weirdities as Si diodes oscillating. Do you have/would Si bipolar transistors, JFETs and depletion-mode MOSFETs indeed tend to freeze out. Enhancement-mode MOSFETs often work, but even them not always. One possibility is that the ohmic contacts freeze even when the channel itself might continue functioning. Maybe another factor is that the modern devices are designed for low supply voltages, so that there is no longer room to use other than enhancement-mode FETs within the voltage budget. I don't know for sure. Regards, Mikko
From: Joerg on 7 Mar 2010 12:02 Okkim Atnarivik wrote: > Spehro Pefhany <speffSNIP(a)interlogdotyou.knowwhat> wrote: > : I thought it was primarily bipolar that had problems with 4K > : (including such weirdities as Si diodes oscillating. Do you have/would > > Si bipolar transistors, JFETs and depletion-mode MOSFETs indeed > tend to freeze out. Enhancement-mode MOSFETs often work, but even them > not always. One possibility is that the ohmic contacts freeze even when > the channel itself might continue functioning. Maybe another factor > is that the modern devices are designed for low supply voltages, so > that there is no longer room to use other than enhancement-mode > FETs within the voltage budget. I don't know for sure. > You can get higher voltage JFETs. Not for pennies, but also not outrageously expensive. -- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
From: JosephKK on 8 Mar 2010 00:02
On Sat, 6 Mar 2010 12:13:57 +0800, "Royston Vasey" <royston(a)vasey.com> wrote: > >"Richard Henry" <pomerado(a)hotmail.com> wrote in message >news:e36c0cd9-637c-4a85-b7a7-2477676956ca(a)p3g2000pra.googlegroups.com... >On Mar 5, 4:59 pm, "amdx" <a...(a)knology.net> wrote: >> That damn global warming! >> >> Several ships, including one small cruise liner, were stuck in ice.... >> More than 30 ships were plagued by the problem and stranded at sea >> until the ice was cut away early today, March 5, 2010. >> >> http://www.examiner.com/x-20221-Long-Island-International-Travel-Exam... >> >> "It has been a lot colder than normal in the southern parts of the Baltic >> Sea. >> But in the north, all is normal, with normal levels of ice." > >Balti Sea Ice service shows current ice conditions to be less than >normal. > >http://www.fmi.fi/weather/index_9.html > > >Come on Richard, no need to confuse and agitate the deniers with facts! >:) > So much fun, your own link undercuts your argument. |