On 01/27/2014 10:25 AM, Zane Healy wrote: Too cold affects mechanical parts due to contraction and lubricant viscosity. Older gear with MECL/ECL and transistors want to have every thing at the same temp and raw trasistor system may not work due to transistor Beta shifting with low temps. Obviously any logic that is marginal will quit or loose margin and be come flaky. The more SSI the more likely, the more integrated the better. I've run gear below freezing and as long as there was no condensation things went well. Condensation is bad so if you bring gear in thats cold allow it to warm and not collect moisture. The spec for most DEC gear explicitly says no condensation. Allison

On Jan 27, 2014, at 9:33 AM, Paul Koning <paulkoning at comcast.net> wrote: I worked on military grade big-iron with both Chilled Water cooling and heavy duty A/C. The A/C was cold enough that I had to wear a coat in the summer in Persian Gulf, and would be wearing it in one of the hottest spots onboard to try and warm up (trust me, that gets you some strange reactions). We made sure we didn't get condensation. Zane -- healyzh at aracnet.com http://www.zanesphotography.com http://www.flickr.com/photos/zanes-photography/ https://www.facebook.com/ZanesPhotography

On Monday (01/27/2014 at 12:33PM -0500), Paul Koning wrote: or, the ETA10, where we just dumped the whole thing in a tank of liquid nitrogen. The same design ran with a 14 to 20nS clock cycle air cooled but when immersed in LN2, ran at 7nS clock. This was in the early 80's. There were over 300 "ALSI 20K" CMOS devices, 380-some pins each, on the 42-layer PCB, which was entirely submerged in the liquid. Chris -- Chris Elmquist

On Jan 27, 2014, at 7:36 AM, Ethan Dicks <ethan.dicks at gmail.com> wrote: While whoever added the garage to the house (and converted the original garage to a family room and the room I use as my office), put up dry wall, I'm pretty sure they didn't include insulation. I know there is none in the attic. As such it gets down to 32F or lower. At that point I turn off the Dehumidifier, and put a heater in front of the computers. Not a major problem this year as the only thing running out there was a router. What I noticed was the gear got noisier without the heater once it got below freezing, that was a pretty good indication to me that things were too cold. Though it's pretty freaky to have cold air coming out of the back of a Compaq XP1000/667 VMS box! :-) Zane -- healyzh at aracnet.com http://www.zanesphotography.com http://www.flickr.com/photos/zanes-photography/ https://www.facebook.com/ZanesPhotography

On Jan 27, 2014, at 12:15 PM, Fred Cisin <cisin at xenosoft.com> wrote: True, once they are running. But there is startup. I?ve seen disk drive specs (for modern storage systems) that show two temperatures: one for operating temperature, and one for startup temperature. For example, you might see 0C to x operating, 5C to x startup. The 5 degree difference is because the electronics heat up the air flowing over the drives by 5 degrees, so what this really means is that the drives want to see 5C to x-5C. paul

Many things will deteriorate slower with colder temperatures. Alas, my arthritic joints are not amongst those. :-(

On 01/28/2014 07:03 AM, Chris Elmquist wrote: I doubt that many have heard of Neil's baby. I'm sure there *was* a minimum temperature of the N2 however. Thermal stresses with it were bad enough at optimum temperature. I think I heard Neil use the term "wet" nitrogen, implying something close to the boiling point. --Chuck

On 01/28/2014 05:38 PM, Chris Elmquist wrote: I remember the "wet nitrogen" thing was in response to a question I'd asked him about "At what temperature do you keep the liquid nitrogen?", so I suppose that was his way of saying "not too cold". Who did the IC fab for the system? Fairchild? Did Neil ever get to build his Super-X-by-God machine? I recall that when I expressed some concern over his hard partition of 16 Kwords for the operating system, he answered, something to the effect of "If you can't fit an operating system into 16K, you don't belong in this business." Old times... --Chuck

On 01/30/2014 09:49 AM, Chris Elmquist wrote: A small environment where everyone's not working at cross purposes can be very rewarding, particularly when you're given an opportunity to find your own way. I have some fond memories from my CDC days--and remember that the shutdown of SVLOPS (I had departed long before that) took some people pretty hard--many of those affected were middle-aged to near retirement. A friend of mine who decided to stick it out until the end failed at finding employment and committed suicide. But the years following the IBM settlement were great--CDC was flush and looking for ways to creatively spend the money. A lot of very interesting stuff happened. The reason I asked about Fairchild is that they were a huge problem in the original STAR-100 construction. I recall that the hangup was the fab for the register file. I don't remember the details, only that it almost never happened. Different logic family than the ETA boxes, however. --Chuck

On Mon, Jan 27, 2014 at 12:12 PM, Fred Cisin <cisin at xenosoft.com> wrote: In the machine rooms? Yes. At Pole, we use outside air controlled through themostatic louvers to cool equipment. By the time it's entering the room, it has been warmed up in the ducts to around -30F/-34C in the winter (maybe -10F/-23C in the summer). With the AMANDA experiment (~19KW in 15 racks), we had to balance the temps between too warm for the HV crates (the air ducts blew right on them) and too cold for the discriminator channels. We had to keep the room between about +41F/5C and +59F/15C. +68F/+20C was too warm. +32F/0C was too cold. The direction and intensity of the wind often caused larger-than-acceptable fluctuations in the quantity of outside air entering the intake making things tricky to manage when it would alternate between storms and calm. In 2005, a year between two of my winters, the environmental process controller in the Ice Cube Observatory building crashed when the louvers were shut. From the reports I got, the room warmed to +120F/+49C before anyone could walk out to the building to mitigate the problem. With +120F in the aisles, some of the racks were substantially warmer, locally. We lost several machines due to heat. When I returned a few weeks later, a couple of the lesser-used boxes were still broken, but all the critical systems had been returned to service. The flip side is, when it's +5F/-15C or +10F/-12C outside (which happens a couple of days every few summers), the air isn't cold enough to keep the room cool through the usual airflow, so we've had to turn equipment off or open doors to move more air. So... "free" Air Conditioning, but if the air stops or gets too warm, it all goes pear-shaped. -ethan

On 01/27/2014 01:03 PM, dwight wrote: OK, so on that note - is there the possibility of lasting damage from running electronics when they're too cold? Or is it more likely that they'll just be glitchy or simply won't work when cold, but will be fine again when warmed up? I'm in much the same situation as Ethan, where one of the rooms I've got vintage equipment in gets down to around 50F until the heaters have brought things up to a more comfortable level, so it's useful to know if there's a risk in trying to operate machines when it's that cold. It sounds like magnetic media should be OK (unless there's an age factor which makes them more susceptible to cold than when new), and that was originally my biggest concern - but maybe I should be worrying about the electronics, too... cheers Jules

On 02/01/2014 08:25 AM, dwight wrote: This brought to mind something used in the music industry--a gizmo called a "Dampp-chaser": http://www.dampp-chaser.com/ They've been around since 1947; basically a very low wattage heating unit to placed inside of pianos and closets and the like. FWIW, Chuck

On Feb 1, 2014, at 12:37 PM, Chuck Guzis <cclist at sydex.com> wrote: The same kind of widget is often found inside gun safes, to avoid rust. paul

On Sat, Feb 01, 2014 at 12:31:13PM -0800, Fred Cisin wrote: [...] There is also the upside that spare parts are readily available. Not in Britain, because we don't use those weird American units :p My favourite non-standard unit for measuring power consumption is ?/watt-year. For 2009-2012, 1W was roughly to ?1/year, which made it dead easy to estimate how much a new toy would cost to run. Sadly, the price is now nearer to ?1.25. (For anybody who is curious, but not curious enough to look it up, 1BTU is roughly 1kJ, and therefore 1BTU/hour is roughly 1kWh.)

On Sat, 15 Feb 2014, Philip Belben wrote: SO, what is a Watt "Equivalent"? (used instead of wattage for peddling CFLs) It claims to mean that the bulb producses light "equivalent" to an incandescent of that wattage, but it seems to be noticeably low.

On 16 February 2014 21:57, Tony Duell <ard at p850ug1.demon.co.uk> wrote: Its capacitors theoretically hold enough energy to blow a speaker of that wattage when it decides to go. So don't blame us (the manufacturer) when it fries the 10W speakers you hooked up to it (which is all it is really capable of driving) a week after you toss the receipt, as the amplifier chip fuses itself into a fraction-of-a-fingernail sized slab of Sillicon. -- Joachim Thiemann :: http://jthiem.bitbucket.org :: http://signalsprocessed.blogspot.com

On 02/01/2014 11:02 AM, Jules Richardson wrote: There is cold and there is COLD. For the moment COLD is near freezing (0C) and cold is 50F. Most will tolerate cold but many not work reliably. That is no harm will likely occur to electronics. the reason I be vague is a large machine like say and older PDP-8 with core may like the cold but core might be on the edge of margin and not work reliably, and the power supplies may drift off the set points make it more unreliable. None of that is permanent failure. HOWEVER, Magnetic media will be potentially damaged! Why? The electronics might go unreliable and write trash or read trash, or worse a positioner may be off and put stuff in a servo area on media. Also lubricants will even is fresh increase in viscosity when cold so things may not move well until they are warmer. The best example of the above was a TTY (asr33) that would not work at below 60 as it needs more pads (CR end dashpot was new and tight fit.) so it took longer to return the carriage. The punch was fussy as well when cold. In the end its a system level call but some parts may not like the cold and other may thrive! Condensation is prohibited as old and likely dusty boards will have some containments that are conductive when wet and will upset bias, signal paths or regulation (power supplies) all can be minimally unreliable or potentially destructive. Also condensation is problematic with older epoxy packaged part as they may absorb moisture over time and when warm convert that to die level corrosion. One last area, temperature cycling. That is going from cold to hot or reverse with a sharp change in temperature over time. This can crack solder joints, bonds to dies, or mess with mechanical tolerances in thing slike tapes and disks. If the machine is cold and you power it the self heating may be great enough to induce the sharp temperature change and stress the construction or connections. In doing so it should be gradual without condensation (dry heat). 50F is cold but generally inside the proscribed range is the air is DRY. I'd suggest that warming to around 60-65 is a good thing. Most of the larger machines make enough heat that keeping the room warm is rarely an issue. Most magnetic media is plastic binder and has a greater physical change than metals over temperature. Think of ferric oxide on aluminum platters with heads at microinches. Take care with mechanical things. Allison

On 01/27/2014 09:53 AM, Paul Koning wrote: Thanks - I think it's mainly the media that I'm concerned about - whether there are problems with the binders used (particularly given that the media is operating way beyond its design life) when it's "cold" (i.e. something quite a bit cooler than typical room temperature). When it comes to motors and actuators I can certainly imagine the lubricants under-performing, but I would expect that they'd still work (albeit with increased wear until they're up to operating temperature) - although as Ethan pointed out there may be problems with drive currents which could cause damage. I was just running my IIgs the other day in a space where the heaters hadn't kicked in, and it was ~52F or so; although I wasn't particularly concerned about the machine itself or the display, it did make me wonder if I should be worried about the floppies/drives. I've seen discussion about high temps on the list in the past, but I don't recall anything about the other end of the scale. cheers Jules