thad@btr.btr.com (06/10/91)
In comp.sys.amiga.games, xanthian@zorch.SF-Bay.ORG (Kent Paul Dolan) wrote in article <1991Jun9.122639.16244@zorch.SF-Bay.ORG>: | rjtatz@magnus.acs.ohio-state.edu (Robert J Tatz) writes: | | > These games got wiped out over 5-6 month gap. One got "jellied" or | > something, so the darn problem is having to use the original. | | As to the "jellied", that was what it looked like after a second instar | cockroach tried to take a merry-go-round ride on one of my floppies; | smeared the little sucker 1/4th of the way around the disk as a jelly. Kent's tale of "Jelly Floppies" brings up a hardware issue that's been a pet peeve of mine for decades: incorrect "fanning" of computers. Background: for years I've been wondering why spiders seek out and enter the floppy drive and/or tape-drive ports on most my computers. And for years I've lamented the excessive need to open the computers every 3-6 months or so and clean out the dust bunnies, hair, etc. that tends to accumulate inside. So how are those two items related? Air flow paths. Informal (read: summertime beer-drinking-related :-) studies have shown that many bugs (the firmware, living/breathing kind (and, yes, I do know that spiders are arachnids and not "bugs", so what? After squishing both, spiders and bugs appear the same. :-) ) tend to follow/track/stalk air currents that diverge from the ambient norm, air patterns such as those resulting from non-weatherstripped house doors, partially-open windows, poorly-insulated vent systems, AND those generated by computer fans. Dust, lint, smoke and other atmospheric contaminants ALSO tend to follow the same air currents. The PROBLEM is that most computers have fans that evacuate inside hot air by sucking the air out. This means that outside "cool" air enters the computer via any openings, typically floppy drive slots; accompanying that outside air will be dust and other contaminants (followed quickly by spiders and bugs :-) The SOLUTION is to create a positive (higher than ambient) air pressure inside the computer which effectively blocks airborne contaminants. Air currents will flow from a high-pressure area (inside the computer) to the low-pressure area (outside the computer); this technique is commonly used for "IC clean rooms" and for hospital surgical theatres. To effect the SOLUTION for a computer basically requires a fan to blow inwards. Because only clean air should enter the computer, a filter is needed at the fan's intake. (And that filter should be removeable and cleanable) Some companies do design their computer cases for positive pressure, and the insides will and DO remain clean for years, thus preventing a dust-blanket buildup. (Such dust-blankets trap and retain heat, and heat is the enemy of all electronic equipment). For those who remember my SCSI talk at BADGE several years ago during which I demo'd the Fujitsu tape drive in a (surplus) IBM case, that case epitomized a properly-designed and filtered positive pressure enclosure for computer equipment. (And, no, that was NOT an IBM-PC case, it was a case from one of IBM's professional line of computers; it could hold two full-height 5-1/4" HDs behind which are mounted the power supply, fan and externally-accessible filter). As a prime example of BAD design which causes me much grief, I point to the external HD/tape-drive case of the Sun 3/60 at my office: two fans sucking air out by blowing through "window-screen" filters. Besides that design's evils of sucking in dust across the tape head and the fact the screens quickly clog preventing air flow, the screens are WELDED to the case making cleaning a very difficult chore. If those screens were omitted, air, albeit dirty, would still flow and the box would not overheat (which it does tend to do due to lack of air flow). [HINT: do NOT operate such computers near carpeted areas, and keep paper, pencil erasings, tissue (e.g. Kleenex), hairy people, etc. away from the machine! :-) ] Point of all this being: a relatively simple parts relocation (probably not even requiring external case modifications) could add an additional aura of professionalism to the Amiga and increase reliability which IS important for those systems operated 24 hrs/day. And a "tip" from mainframe systems would be the use of an air-flow sensor along with an overtemperature (thermal) switch; a "trigger" from either sensor could, say, throw up a requester or ALERT (for AmigaDOS) or initiate a proper, automatic, sequenced shutdown (for Amiga UNIX). In the absence of air-flow sensors, it is still possible to design a "cooling" system that will move air (even if the filters ARE clogged) using inexpensive pressure-differential-sensing ducting flaps (which appear like the vacuum- operated "doors" used in automotive passenger-area air-conditioning systems). Comments on this topic are invited, and suggestions how to retrofit existing Amiga systems are welcome. Thad Floryan [ thad@btr.com (OR) {decwrl, mips, fernwood}!btr!thad ]
peterk@cbmger.UUCP (Peter Kittel GERMANY) (06/10/91)
In article <3004@public.BTR.COM> thad@btr.btr.com writes: > >So how are those two items related? Air flow paths. > >To effect the SOLUTION for a computer basically requires a fan to blow inwards. >Because only clean air should enter the computer, a filter is needed at the >fan's intake. (And that filter should be removeable and cleanable) Well, one difference between light rays and air flow is that the path of the former is reversible, the one of the latter not. We have discussed this already with engineering and when I remember correctly they always told us: When the fan sucks the air out, it is much more possible to direct the flow (by choosing inlet openings) to areas inside the case that need cooling (processor, expansion cards,...), than it would be possible with a fan blowing into the case (please don't ask ME for details, I'm only a physicist... :-). I always said something like "aha". Perhaps it really is this way, and you only could make it really working by having two or more fans, and that would be too expensive. But now I'm finally speculating. -- Best regards, Dr. Peter Kittel // E-Mail to \\ Only my personal opinions... Commodore Frankfurt, Germany \X/ {uunet|pyramid|rutgers}!cbmvax!cbmger!peterk
FelineGrace@cup.portal.com (Dana B Bourgeois) (06/11/91)
[in response to Thad's posting about correct cooling air flow design in computer equipment...] I'll just tell this little tale and not moralize about it. :) ABout 6 years ago, I was at our annual family reunion held in Portland, Or. One of my cousins worked at <local electronics manufacturer> and they had a project that packed quite a bit of heat-generating stuff into a modern looking pedestal case. No one working on the project had experience in cooling design. They were having over-heating problems. Another cousin made some remarks about how to fix the problem. A lively discussion ensued. The bottom line is that these guys were without a clue on how to design the cooling air flow path. They were ready to listen to anybody who sounded reasonable and who didn't recommend a redesign. This is perhaps extreme but I think a lot of design teams do not have an expert on cooling during the concept phase and if no heating problems are experienced during proto-typing I would guess that no expertise will ever be called in until feedback from manufacturing or from customers causes changes to the design. HOpefully it is not this bad now. Hopefully companies take cooling into account when designing equipment. Then again, maybe the need ahas gone away with the big heat generators (power transistors, tubes, linear power supplies, etc.) and even less expertese is around than before. I don't know. But echoing Thad, it would be nice (very nice!!!) if maintenance in dusty environments were part of the design parameters. Dana Bourgeois @ cup.portal.com
FelineGrace@cup.portal.com (Dana B Bourgeois) (06/11/91)
By the way, in case no one else points it out, the reason so many designs are done with the fan blowing the air out of the case is that it is easier to design this way. Changes to flow paths are easily made (at almost any time) by changing the hole patterns in the sheet metal. It is also easier to avoid hot spot/stagnant air areas by pulling the air out of the case. I have heard about designs that overheat where the fix was to turn the fan around from pressurizing the case to sucking on the case. That may be why only the more expensive and heavily designed equipment has pressurized cooling. Takes more engineeing to do it that way. Dana Bourgeois @ cup.portal.com
mks@cbmvax.commodore.com (Michael Sinz) (06/11/91)
In article <43149@cup.portal.com> FelineGrace@cup.portal.com (Dana B Bourgeois) writes: >[in response to Thad's posting about correct cooling air flow design >in computer equipment...] > >This is perhaps extreme but I think a lot of design teams do not have >an expert on cooling during the concept phase and if no heating >problems are experienced during proto-typing I would guess that no >expertise will ever be called in until feedback from manufacturing or >from customers causes changes to the design. > >HOpefully it is not this bad now. Hopefully companies take cooling >into account when designing equipment. Then again, maybe the need >ahas gone away with the big heat generators (power transistors, >tubes, linear power supplies, etc.) and even less expertese is around >than before. I don't know. But echoing Thad, it would be nice (very >nice!!!) if maintenance in dusty environments were part of the design >parameters. If you play with the A3000, you will note that much effort went into the air flow design. The hardware guys did a great job with it. However, air flow is so critical that the A3000 will overheat if the cover is off. That is, the A3000 is cooler when it is correctly closed in its cover. Air flow is rather interesting. You can cause a very nice and controlled air flow by removing air from an area and let it get filled in by air coming from other areas. If you select the openings correctly, you have full control of where the air comes from to equalize the pressure. Pushing air in does not give you any control. The pressure will just grow and it will try to find any easy path out. The path is changed due to the turbulance of the fan, etc. In either case, air flow for cooling is somewhat of a black art. It is much like good speaker design: Many of the parameters are known but it takes something "extra" to get it really right. /----------------------------------------------------------------------\ | /// Michael Sinz - Amiga Software Engineer | | /// Operating System Development Group | | /// BIX: msinz UUNET: rutgers!cbmvax!mks | |\\\/// | | \XX/ "I don't think so" said Ren'e Descartes, then he vanished. | \----------------------------------------------------------------------/
thad@public.BTR.COM (Thaddeus P. Floryan) (06/11/91)
In article <1339@cbmger.UUCP> peterk@cbmger.UUCP (Peter Kittel GERMANY) writes: >[...] >Well, one difference between light rays and air flow is that the path >of the former is reversible, the one of the latter not. We have discussed >this already with engineering and when I remember correctly they always >told us: When the fan sucks the air out, it is much more possible to >direct the flow (by choosing inlet openings) to areas inside the case >that need cooling (processor, expansion cards,...), than it would be >possible with a fan blowing into the case (please don't ask ME for >details, I'm only a physicist... :-). >[...] Yes, I can see how the flow path "may" be easier to control, but the issues of inside cleanliness and "best" cooling are ignored (or sidestepped (in the interests of "economy")). As a for-instance, I can look at ANY one of my Amigas at home or at the office and clearly see where the air enters the systems due to: dust buildup at the expansion port connector (A1000), dust buildup around the external video/floppy connectors, dust buildup around the joystick connectors, and dust buildup in and around the floppy drive(s). The dust buildup around the floppy drive(s) is the worst ... what has happened to me many times is the optical sensor that detects the write-protect tab on a floppy gets obscured thus permitting the floppy to be (potentially) written-to (which is NOT nice in a virus-infested real-world). Though it's been nearly 30 years since I've taken any course in thermo-dynamics (and I've forgotten most of it/them :-), I'd like to cite one practical, real- world observation that anyone can verify: a fan blowing ONTO a power supply will keep the supply cooler than will a fan sucking air OVER a power supply. Since one of my companies used to make the power supplies for modem companies such as Ven-Tel, Racal-Vadic, and others (over 25,000 power supplies a month), I have a large notebook of measurements of various tests made using fans and YSI thermocouples regarding power supply heating, cooling, and related probs. If you want to perform a simple test for yourself, quickly go do some exercise and work up a sweat. Then choose to cool off by either: (a) standing in front of a fan blowing on you, or (b) standing behind a fan sucking air around you. I'm sure you'll quickly agree that choice (a) cools you better! :-) Choice (a) is similar to a case-mounted computer fan blowing IN over the power supply and other heat-generating parts. If it takes two fans to cool a case such as the Amiga's, so be it. There ARE quiet fans which can move a LOT of air efficiently (I have 5 cases here in my lab operating that way to show anyone who cares to visit (cases from IBM and from some outfit named "Systems Integrators, Inc." that I acquired surplus).) Thad Floryan [ thad@btr.com (OR) {decwrl, mips, fernwood}!btr!thad ]
kermode@shiva.trl.OZ.AU (Roger Kermode) (06/12/91)
thad@public.BTR.COM (Thaddeus P. Floryan) writes: >As a for-instance, I can look at ANY one of my Amigas at home or at the office >and clearly see where the air enters the systems due to: > dust buildup at the expansion port connector (A1000), > dust buildup around the external video/floppy connectors, > dust buildup around the joystick connectors, and > dust buildup in and around the floppy drive(s). >The dust buildup around the floppy drive(s) is the worst ... what has happened >to me many times is the optical sensor that detects the write-protect tab on a >floppy gets obscured thus permitting the floppy to be (potentially) written-to >(which is NOT nice in a virus-infested real-world). >Though it's been nearly 30 years since I've taken any course in thermo-dynamics >(and I've forgotten most of it/them :-), I'd like to cite one practical, real- >world observation that anyone can verify: > a fan blowing ONTO a power supply will keep the supply cooler than > will a fan sucking air OVER a power supply. >Since one of my companies used to make the power supplies for modem companies >such as Ven-Tel, Racal-Vadic, and others (over 25,000 power supplies a month), >I have a large notebook of measurements of various tests made using fans and >YSI thermocouples regarding power supply heating, cooling, and related probs. >If you want to perform a simple test for yourself, quickly go do some exercise >and work up a sweat. Then choose to cool off by either: > (a) standing in front of a fan blowing on you, or > (b) standing behind a fan sucking air around you. >I'm sure you'll quickly agree that choice (a) cools you better! :-) I agree, but the power supply is not the one and only thing that has to be cooled inside the amiga. In the A1000 the fan blows air out of the case, air taken from the power supply which is in turn taken from the rest of the A1000s inards. If this fan was blowing air in it would be blowing *heated* air over the ICs, decreasing the effective rate of cooling. Why not move the blow type fan so that it blows the air over the ICs and out through the power supply? The answer to this was given in a previous post, it's much easier to *control* the air flow inside the case using a suck type fan which creates a marginal negative air pressure inside the case relative to the air pressure outside the case. Air flow is then controled by the aperture size of the vents in the comoputer case and the way obstacles are arranged within the case. This method allows for much greater *control* of the air flow over a *wider* area inside the case ensuring that *all* components can be kept within their specified operating temperatures. >Thad Floryan [ thad@btr.com (OR) {decwrl, mips, fernwood}!btr!thad ] Roger Kermode, Telecom Research Laboratories | " I didn't do it, ACSnet[AARN/Internet] r.kermode@trl.oz[.au] | they didn't see me do it, Snail : PO Box 249 Clayton, Victoria, 3168, | they can't prove a thing!" STANDARD DISCLAIMERS APPLY | - Bartholomew J Simpson
peterk@cbmger.UUCP (Peter Kittel GERMANY) (06/12/91)
In article <3025@public.BTR.COM> thad@public.BTR.COM (Thaddeus P. Floryan) writes: >In article <1339@cbmger.UUCP> peterk@cbmger.UUCP (Peter Kittel GERMANY) writes: >>[...] >>Well, one difference between light rays and air flow is that the path >>of the former is reversible, the one of the latter not. > >Though it's been nearly 30 years since I've taken any course in thermo-dynamics >(and I've forgotten most of it/them :-), I'd like to cite one practical, real- >world observation that anyone can verify: > > a fan blowing ONTO a power supply will keep the supply cooler than > will a fan sucking air OVER a power supply. > ... >Since one of my companies used to make the power supplies .... Carefull: the power supply is *not* the main problem. You must equally take care of the mainboard (high processor speeds mean real heat), RAM banks, plus everything a user chooses to plug into an expansion slot. So you have very distributed heat generation where you have to provide a suitable air flow that really reaches every place inside your case. >If you want to perform a simple test for yourself, quickly go do some exercise >and work up a sweat. Then choose to cool off by either: > > (a) standing in front of a fan blowing on you, or > (b) standing behind a fan sucking air around you. This is a bad analogy. You would have to add a narrow tunnel (the case) where you're standing in. Then the difference decreases obviously. > There ARE quiet fans ... Oh yes, that inside the A1000 was the quietest fan we ever had. I loved it. -- Best regards, Dr. Peter Kittel // E-Mail to \\ Only my personal opinions... Commodore Frankfurt, Germany \X/ {uunet|pyramid|rutgers}!cbmvax!cbmger!peterk
peck@sol.ral.rpi.edu (Joseph Peck) (06/13/91)
In article <1346@cbmger.UUCP> peterk@cbmger.UUCP (Peter Kittel GERMANY) writes: >In article <3025@public.BTR.COM> thad@public.BTR.COM (Thaddeus P. Floryan) writes: >>In article <1339@cbmger.UUCP> peterk@cbmger.UUCP (Peter Kittel GERMANY) writes: >> There ARE quiet fans ... > >Oh yes, that inside the A1000 was the quietest fan we ever had. I loved it. As a matter of fact, I took me two *years* before I realized that my A1000 even had a fan! I used to worry about overheating :) Now my roommates A2000 is another story all together..... >-- >Best regards, Dr. Peter Kittel // E-Mail to \\ Only my personal opinions... >Commodore Frankfurt, Germany \X/ {uunet|pyramid|rutgers}!cbmvax!cbmger!peterk Joe Peck peck@ral.rpi.edu
elg@elgamy.RAIDERNET.COM (Eric Lee Green) (06/14/91)
From article <3025@public.BTR.COM>, by thad@public.BTR.COM (Thaddeus P. Floryan): > In article <1339@cbmger.UUCP> peterk@cbmger.UUCP (Peter Kittel GERMANY) writes: >>told us: When the fan sucks the air out, it is much more possible to >>direct the flow (by choosing inlet openings) to areas inside the case >>that need cooling (processor, expansion cards,...), than it would be >>possible with a fan blowing into the case (please don't ask ME for >>details, I'm only a physicist... :-). >>[...] > > As a for-instance, I can look at ANY one of my Amigas at home or at the office > and clearly see where the air enters the systems due to: [dust] I'm just curious. I'm not such a fastidious housecleaner myself, but I haven't had this rampant dust buildup that you so decry. Every time I open the case I make a swipe at it with my wet-dry vac, of course, but last time I did that was back in February when I installed a BridgeBoard. Do you live in, like, a high dust area? > a fan blowing ONTO a power supply will keep the supply cooler than > will a fan sucking air OVER a power supply. Correction: AIR blowing onto a power supply will keep the supply cooler than will a fan sucking air over the power supply. Whether that air is coming from a fan or from a case opening doesn't matter. > If you want to perform a simple test for yourself, quickly go do some exercise > and work up a sweat. Then choose to cool off by either: > > (a) standing in front of a fan blowing on you, or > (b) standing behind a fan sucking air around you. > > I'm sure you'll quickly agree that choice (a) cools you better! :-) Down here in the Southland, before the advent of air conditioning, we had something called the "attic fan". Basically, it was a huge fan up in the attic that sucked air through a large opening in the hallway ceiling and blew it into the attic and thus out the eaves. I remember when I was a kid, and the attic fan was on. I'd be all hot and sweaty (remember, 95 degree weather and no air conditioning), and the fan would be on, and I'd stand in front of an open window and let the airflow cool me off. Of course, I would have first gone and shut most of the other windows! Anyhow, the effect was even more cooling than standing in front of the fan. At picnics etc. I'd see similar fans mounted in frames blowing huge gusts of air, but with it sucking air out of the house, we could get a more concentrated airflow by shutting most of the windows and turning the house into a REALLY low-pressure zone. Could get a virtual hurricane blowing through a window then, far more than could be done by any fan that would have fit in that window. I haven't seen an attic fan down here in any house built since 1960. Would be great for spring and autumn and those warm winter days that hit the 70's down here in the Southland, but homebuilders down here ignore such things while following "trends" (which, in the homebuilding industry, tend to be set in places like Massachusetts and New York, sigh). In any event, back to the issue in question, yes, fans sucking air OUT of an area can be quite as effective as fans blowing air INTO an area. Especially when it's a multi-segmented area such as a house or computer, where airflow can be easily adjusted by adjusting the "windows". (Ah, anybody remember reversible window fans? If you wanted to cool one room, blow air into that room... if you wanted to cool the whole house, blow air OUT). > Thad Floryan [ thad@btr.com (OR) {decwrl, mips, fernwood}!btr!thad ] I assume you've never been a Southerner in the pre-air-conditioner era? You learn a lot about fans and cooling under such conditions :-). -- Eric Lee Green (318) 984-1820 P.O. Box 92191 Lafayette, LA 70509 elg@elgamy.RAIDERNET.COM uunet!mjbtn!raider!elgamy!elg
urjlew@ecsvax.uncecs.edu (Rostyk Lewyckyj) (06/15/91)
Regarding suck it in cooling. Well the designers don't just drill holes in the case wherever they want to get some extra air flow. The air usually comes in, in a fairly well defined area. In the A3000 it appears to be the front grill under the diskette slot and the diskette slot itself. So how about some cleanable filters on the air intake grill and a diskette drive bezel with a spring loaded cover. The Convex in our machine room is a big heater and it exhausts it's hot air, so it isn't just small equipment that gets designed that way. But I believe that it has air filters on the intake grilles. Our IBM 3090 is mostly water cooled, and I can't remember whether our STK disk drives suck it in or blow it out. But I remeber seeing the maintenance engineer vacuming off some filters and they were somewhat largish, so I will guess the were on the intake side. Of course with filters in place the grill area must be enlarged and the fan needs to be stronger to get equivalent air flow.
thad@public.BTR.COM (Thaddeus P. Floryan) (06/16/91)
In article <00676835659@elgamy.RAIDERNET.COM> elg@elgamy.RAIDERNET.COM (Eric Lee Green) writes: > [...] > I'm just curious. I'm not such a fastidious housecleaner myself, but I > haven't had this rampant dust buildup that you so decry. Every time I open > the case I make a swipe at it with my wet-dry vac, of course, but last time > I did that was back in February when I installed a BridgeBoard. Do you live > in, like, a high dust area? As many who've visited can attest, my "setup" is quite clean. But this is Silicon Valley, and I have to clean the windows on my car every 2 days or so due to pollution/dirt/grime/etc. atmospheric contaminants. As far as the computers go, I suspect the problem is paper "dust" from printers; the "crud" that builds up is a gray-colored "fluffy" material; note, too, that it's only every 6 months or so I powerdown to clean the innards (and find the "crud"). >> a fan blowing ONTO a power supply will keep the supply cooler than >> will a fan sucking air OVER a power supply. > >Correction: AIR blowing onto a power supply will keep the supply cooler >than will a fan sucking air over the power supply. Whether that air is >coming from a fan or from a case opening doesn't matter. Six of one, half-a-dozen of the other! :-) A fan blowing directly onto the power supply and/or other heat-generating parts will continue to cool them, contrasted to a cooling system designed to evacuate hot air from an enclosure. A recent response from someone at Commodore clearly stated the A3000 *will* overheat if operated with its cover removed. >> If you want to perform a simple test for yourself, quickly go do some >> exercise and work up a sweat. Then choose to cool off by either: >> >> (a) standing in front of a fan blowing on you, or >> (b) standing behind a fan sucking air around you. >> >> I'm sure you'll quickly agree that choice (a) cools you better! :-) > > Down here in the Southland, before the advent of air conditioning, we > had something called the "attic fan". Basically, it was a huge fan up in > the attic that sucked air through a large opening in the hallway ceiling > and blew it into the attic and thus out the eaves. > [...] > In any event, back to the issue in question, yes, fans sucking air OUT of > an area can be quite as effective as fans blowing air INTO an area. > Especially when it's a multi-segmented area such as a house or computer, > where airflow can be easily adjusted by adjusting the "windows". (Ah, > anybody remember reversible window fans? If you wanted to cool one room, > blow air into that room... if you wanted to cool the whole house, blow air > OUT). > [...] > I assume you've never been a Southerner in the pre-air-conditioner era? > You learn a lot about fans and cooling under such conditions :-). Well, would having lived in San Antonio TX for 5-1/2 years, El Paso TX for 3 years, Las Cruces/White Sands Missile Range NM for 4 years, etc. qualify as being a "Southerner" ? :-) [An aside: TX and NM, though "hot", were nothing like the East Coast with its 95F and 95%RH (i.e. Washington DC, New York NY, Florida, Pennsylvania, etc.] Back then, (1950's and early 1960's) we had evaporative coolers that clearly blew cooled air INTO the houses/domiciles. Most home air conditioners, even today, blow refrigerated air INTO the home. Someone commented that wind tunnels suck air over their test areas. Hmmm, the world's largest wind tunnels (NASA/Ames Research Center) are just about 5 miles from where I'm sitting right now , and, as an AIAA member, I visit that site often enough to recall that their fans are blowers (per my recollection). Whatever, THOSE fans are NOT for cooling but, instead, for testing supersonic flight dynamics; nothing to do with venting hot air out of a computer. But I digress. I still maintain that a filtered positive-pressure computer cooling system is "better" than a non-filtered volumetric-evacuation system (as in the Amiga and most consumer systems), especially when the possibility exists (as with the Amiga) for overheating (when operated with the cover removed). Oh, sheesh, this opens up the door to a LOT of humor possibilties for cooling technique acronyms! :-) To wit: ASS = Air Suck System BIT = Blow It Through PIT = Pull It Through SIO = Suck It Out BII = Blow It In FITBIT = Filter It Totally, Blow It Through BARF = Blow Air Reasonably Fast FART = Forwarding Air Rapidly Through BITBLT = Blow It Through, But Leave Parts (on the board :-) etc. Seriously, I'm the guy who put IC cooling fins on my C64's IC chips seven years ago (that computer ran HOT), so I really don't want to make light of the need for proper cooling. I started this "thread" because I feel the issue of cooling (and cleanliness) has NOT been properly addressed by most manufacturers (along with the issue of "quiet" computers.) As just one example (which some of you have seen), I converted one of my AT&T 3B1 systems to a tower configuration earlier this year and showed it at the Silicon Valley AT&T UNIX Users' Group meeting; the overwhelming comment from everyone was "Is it on?" because I applied my theory of cooling to that system and changed the location of the fan ... the system actually runs BELOW ambient (measured using a YSI 43TC multiple thermocouple temperature instrument output to a Gould plotter) and it's almost totally SILENT except for the whirring of the hard drive ... I'm using the EXACT same fan that was in the stock 3B1. So it CAN be done, with filtered air, and a clean system as a (side) benefit. Thad Floryan [ thad@btr.com (OR) {decwrl, mips, fernwood}!btr!thad ]
dale@boing.UUCP (Dale Luck) (06/16/91)
In article <00676835659@elgamy.RAIDERNET.COM> elg@elgamy.RAIDERNET.COM (Eric Lee Green) writes: > >In any event, back to the issue in question, yes, fans sucking air OUT of >an area can be quite as effective as fans blowing air INTO an area. There is at least one difference that I know of though. Although the volume of air will be the same in both cases, the mass of the air is different. I fan sucking hot air out of a hot box will cause less air to be drawn in, than the same identical fan blowing cool air into that same hot box. While the air is in the box, it expands due to the accumulation of energy. Similarly, designs must also consider heated/hot air rising. It does not make much sense to put a sucker at the bottom of a card cage or a blower at the top of a card cage since they are working against the normal flow of heat air. Just another .02 worth -- Dale Luck GfxBase/Boing, Inc. {uunet!cbmvax|pyramid}!amiga!boing!dale
aduncan@rhea.trl.OZ.AU (Allan Duncan) (06/17/91)
From article <3079@public.BTR.COM>, by thad@public.BTR.COM (Thaddeus P. Floryan): > In article <00676835659@elgamy.RAIDERNET.COM> elg@elgamy.RAIDERNET.COM (Eric Lee Green) writes: >>> a fan blowing ONTO a power supply will keep the supply cooler than >>> will a fan sucking air OVER a power supply. >> >>Correction: AIR blowing onto a power supply will keep the supply cooler >>than will a fan sucking air over the power supply. Whether that air is >>coming from a fan or from a case opening doesn't matter. > > Six of one, half-a-dozen of the other! :-) Not really, if the fan is blowing directly onto the power supply, there will be substantial turbulence in the air flow which promotes heat transfer. Air being sucked at moderate speeds is laminar flow, and will leaves an insulating layer of still air on the component surface. [...] > As just one example (which some of you have seen), I converted one of my AT&T > 3B1 systems to a tower configuration earlier this year and showed it at the > Silicon Valley AT&T UNIX Users' Group meeting; the overwhelming comment from > everyone was "Is it on?" because I applied my theory of cooling to that system > and changed the location of the fan ... the system actually runs BELOW ambient ^^^^^^^^^^^^^ Eh? Patent it quick! (Or, look carefully at your calibration procedure) > (measured using a YSI 43TC multiple thermocouple temperature instrument output > to a Gould plotter) and it's almost totally SILENT except for the whirring of > the hard drive ... I'm using the EXACT same fan that was in the stock 3B1. So > it CAN be done, with filtered air, and a clean system as a (side) benefit. Allan Duncan ACSnet a.duncan@trl.oz (+613) 541 6708 Internet a.duncan@trl.oz.au UUCP {uunet,hplabs,ukc}!munnari!trl.oz.au!a.duncan Telecom Research Labs, PO Box 249, Clayton, Victoria, 3168, Australia.
thad@public.BTR.COM (Thaddeus P. Floryan) (06/17/91)
In article <1991Jun16.225909.26026@trl.oz.au> aduncan@rhea.trl.OZ.AU (Allan Duncan) writes: >[...] >> everyone was "Is it on?" because I applied my theory of cooling to that system >> and changed the location of the fan ... the system actually runs BELOW ambient > ^^^^^^^^^^^^^ >Eh? Patent it quick! (Or, look carefully at your calibration >procedure) >[...] Hah! :-) One sensor (the "ambient") was suspended above my workbench, the others were affixed by DOW Heat Sink Compound to various locations inside the system, on the motherboard, etc. The system felt cool to the touch, contrasted to a "standard" system which feels hot (to me). I don't believe I've violated any Laws of Thermodynamics although, come to think of it, the air-suspended sensor "could" have been warmed by the high-intensity incandescent lamps I use; not quite a patentable situation! :-) Actually, this may be of interest: the new location of the fan is one of being suspended above the motherboard INSIDE the system (not along any case walls) both blowing and sucking air across the boards (two tiers). The air intake along the front of the tower case is filtered using some plastic filter pads I picked up at (the local) Weird Stuff Warehouse. The fan is fastened with silicone washers and nylon hardware to an "L" bracket secured to the case's pan and in front of the power supply (245W). Thad Floryan [ thad@btr.com (OR) {decwrl, mips, fernwood}!btr!thad ]
holgerl@amiux.agsc.sub.org (Holger Lubitz) (06/17/91)
In article <1346@cbmger.UUCP> peterk@cbmger.UUCP (Peter Kittel GERMANY) writes: >Oh yes, that inside the A1000 was the quietest fan we ever had. I loved it. So did I. Why had Commodore to choose so noisy ones for the A3000 and especially the A2000 ? They're desktop computers, not towers or file servers. And I don't really want a desktop computer sitting on my desk which has a fan that is so loud that you hardly ever hear the hard disk. Granted, the quiet ones are a bit more expensive. But I surely would have happily paid some bucks more for my A3000UX if it had a fan as quiet as the fan of my 1000. And a few dollars shouldn't make any difference on a $4k machine anyways, should they ? Best regards, Holger -- Holger Lubitz, Kl. Drakenburger Str. 24, D-W-3070 Nienburg/Weser
elg@elgamy.raidernet.com (Eric Lee Green) (06/19/91)
From article <3079@public.BTR.COM>, by thad@public.BTR.COM (Thaddeus P. Floryan): > In article <00676835659@elgamy.RAIDERNET.COM> elg@elgamy.RAIDERNET.COM (Eric Lee Green) writes: >> I assume you've never been a Southerner in the pre-air-conditioner era? >> You learn a lot about fans and cooling under such conditions :-). > > Well, would having lived in San Antonio TX for 5-1/2 years, El Paso TX for > 3 years, Las Cruces/White Sands Missile Range NM for 4 years, etc. qualify > as being a "Southerner" ? :-) No, because of the low relative humidity. Think of Florida. Evaporative coolers are useless in this kind of humidity, down here in the real Southland. Before the advent of inexpensive air-conditioning, but after the advent of electric fans, the electric fan was the major player. Cooling a whole house with an electric fan, whether it be a window fan or an attic fan, was done by sucking air OUT of the house, as I mentioned before. With careful consideration of window placement (while designing the house) and window openings (while living in the house), you could get it so that, e.g., a cool breeze blew through the dining room window, through the kitchen, then out the window fan in the back bedroom. If you'd had the window fan blowing inwards, it would have only "cooled" the back bedroom. Which would have left you sweltering in the dining room and kitchen. A computer is similar to a house in that plugging in cards chops it up into "rooms". It's simply impossible to blow air directly on each and every card to eliminate heat buildup, unless you have a fan for every "room". > Back then, (1950's and early 1960's) we had evaporative coolers that clearly > blew cooled air INTO the houses/domiciles. Most home air conditioners, even > today, blow refrigerated air INTO the home. Bad comparison. Home air conditioners have a vent for every room -- basically, they've split up the fan to send part of its flow to each compartment. I suppose a case could be designed that would have forced-air ducts in it, but that'd be expensive (since you couldn't just stamp it out of sheet metal or pour it into a one-piece plastic mold). > I still maintain that a filtered positive-pressure computer cooling system is > "better" than a non-filtered volumetric-evacuation system True, to some extent. However, it's difficult to design such a forced-air cooling system, due to the ductwork required. Plus the filters tend to clog. Most home computers don't have a serviceman on service contract come by every month to change the air filters. -- Eric Lee Green (318) 984-1820 P.O. Box 92191 Lafayette, LA 70509 elg@elgamy.RAIDERNET.COM uunet!mjbtn!raider!elgamy!elg Looking for a job... Unix/Amiga/C... tips, leads appreciated.
perley@trub (Donald P Perley) (06/20/91)
In article <3079@public.BTR.COM>, thad@public (Thaddeus P. Floryan) writes: > >I still maintain that a filtered positive-pressure computer cooling system is >"better" than a non-filtered volumetric-evacuation system (as in the Amiga and >most consumer systems), especially when the possibility exists (as with the >Amiga) for overheating (when operated with the cover removed). Part of the problem is that the cover is acting as part of the ductwork. Positive pressure cooling would fail as well, unless you had a fan for each board on the buss. -- perley@trub.crd.ge.com
rkushner@sycom.UUCP (Ronald Kushner) (06/20/91)
perley@trub (Donald P Perley) writes: >In article <3079@public.BTR.COM>, thad@public (Thaddeus P. Floryan) writes: >> >>I still maintain that a filtered positive-pressure computer cooling system is >>"better" than a non-filtered volumetric-evacuation system (as in the Amiga an >>most consumer systems), especially when the possibility exists (as with the >>Amiga) for overheating (when operated with the cover removed). > >Part of the problem is that the cover is acting as part of the ductwork. >Positive pressure cooling would fail as well, unless you had a fan for each >board on the buss. Actually, if you did pipe the air into the computer through a small duct system, you could probably control where and what its blowing on, and also an custom designed exahust system.....And it might be noisier, and add to the cost of each unit!! I can see them welding pipes together into a manifold... Whenever we put Air Handlers into houses, by biggest beef was the noise, they only had one Cold Air Return somewhere in a central location....with exhausts (vents) around the outside wall of the house...If your so damn worried about dust in your computer, call your local HVAC contractor and have an electronic air cleaner or those huge filters (Spaceguard?) installed in your heating/cooling system. They do work well...And you got a choice of many American made products from Honeywell, Trion and United Technologies (UT's brand names are Carrier, Bryant, Day and Night, Payne)... -- C-UseNet V0.42e Ronald Kushner Life in Hell BBS +1 (313) 939-6666 P.O. Box 353 14400 USR HST V.42 & V.42bis Sterling Heights, MI 48311-0353 Complete Amiga Support UUCP: uunet!umich!vela!sycom!rkushner (We are not satanic, just NUTS!) I KNOW, I LISTEN TO MARK SCOTT
thad@public.BTR.COM (Thaddeus P. Floryan) (06/20/91)
In article <00677315168@elgamy.raidernet.com> elg@elgamy.raidernet.com (Eric Lee Green) writes: >From article <3079@public.BTR.COM>, by thad@public.BTR.COM (Thaddeus P. Floryan): >[...] >> I still maintain that a filtered positive-pressure computer cooling system is >> "better" than a non-filtered volumetric-evacuation system > >True, to some extent. However, it's difficult to design such a forced-air >cooling system, due to the ductwork required. Plus the filters tend to >clog. Most home computers don't have a serviceman on service contract come >by every month to change the air filters. Hmmm. I have "heard" that one of the uses to which Apple puts their Cray is for the modeling/simulation of heat flow (and cooling) of their designs. Interestingly, Sam Dicker (ex-Amiga/Los Gatos, and the author of audio.device) is the guy who operates that Cray for Apple; after the 1986 layoffs he needed a job and Apple was hiring ... he said "no way will I work on Macs" but I suppose the attraction of the Cray (and the need to put bread on the table) forced his hand. BTW, I cross-posted part of my article re: humorous cooling system acronyms to comp.sys.3b1 (re: "ASS = Air Suck System; .. ; FART = Forwarding Air Rapidly Through; ...") and one person (there) came up with ``FARTASS'' which is a combined dual-fan Suck It Out, Blow It In arrangement! :-) Oh well, maybe I'll just repackage my Amigas in tower cases (like that one 3B1) and at least *I* won't have to worry any more about dust, heat and noise. Hmm, maybe this *IS* a business opportunity! :-) Gee, this might "make my day" almost as much as when I heard from an Apple marketing VP they lost the $400 Million U.S.Gov't contract and now don't give a hoot about UNIX anymore (on the Mac). Thad Floryan [ thad@btr.com (OR) {decwrl, mips, fernwood}!btr!thad ]
FelineGrace@cup.portal.com (Dana B Bourgeois) (06/22/91)
Thad, I think your basic point is correct: A positive pressure cooling system is 'better' for cleanliness than a negative one. I just don't see how commercial companies can implement it reliably at a reasonable cost point. I'd spend $10 or $20 bucks extra for positive cooling but not $100 or $200. I'd rather get out the vacuum cleaner at regular intervals. As was mentioned several times, positive pressure systems are funny creatures to design. It's sorta like when you try to design a waterfall. Even very small variations in the lip can make big changes in the water flow and volume. So inside the case, flow is determined by the easiest path to the largest outlet. But there are many paths and small variations between paths (like a developing air leak in the case, a new expansion card, or even the built up crud on your filter) can result in large variations of air flow. That variation can result in large temperature swings in the electronics. So for cost and reliability reasons I can understand why home PCs are either suck-cooled or naturally blown (by convection). :) Regarding your internal fan, I know you know that suspended inside the case as you describe will spend most of its energy circulating its output to its input without doing much 'work'. So I have to ask, how does the air get into your case? (and out of it?) Fan noise is caused by motor speed (actually blade tip speed), blade edge shape, and by pressure drop. A fan contained inside a case and working with a very small pressure drop across it would give off minimal noise. Dana Bourgeois @ cup.portal.com
bernie@metapro.DIALix.oz.au (Bernd Felsche) (06/22/91)
In <00677315168@elgamy.raidernet.com> elg@elgamy.raidernet.com (Eric Lee Green) writes: >A computer is similar to a house in that plugging in cards chops it up into >"rooms". It's simply impossible to blow air directly on each and every card >to eliminate heat buildup, unless you have a fan for every "room". Wrong. By careful design of the air ducts and blower location(s), a multitude of PICs can be adequately cooled. Unfortunately, this level of engineering is lacking in cheaper enclosures and systems. >> I still maintain that a filtered positive-pressure computer cooling system is >> "better" than a non-filtered volumetric-evacuation system >True, to some extent. However, it's difficult to design such a forced-air >cooling system, due to the ductwork required. Plus the filters tend to >clog. Most home computers don't have a serviceman on service contract come >by every month to change the air filters. Ahh. Wouldn't it be nice if the machine told you that it was getting too hot? This is not impossible, and can be done relatively cheaply. The problem lies partly with expectations: "What would you expect the computer to do?" Even better, a small compressor could build up enough pressure, which, when expelled through a shock tube, could cause the gunge to be blown off the filter, and onto the user :-) -- Bernd Felsche, _--_|\ #include <std/disclaimer.h> Metapro Systems, / sold \ Fax: +61 9 472 3337 328 Albany Highway, \_.--._/ Phone: +61 9 362 9355 Victoria Park, Western Australia v Email: bernie@metapro.DIALix.oz.au
perley@galaxy (Donald P Perley) (06/28/91)
In article <1991Jun22.111516.8865@metapro.DIALix.oz.au>, bernie@metapro (Bernd Felsche) writes: > >>clog. Most home computers don't have a serviceman on service contract come >>by every month to change the air filters. >Even better, a small compressor could build up enough pressure, which, >when expelled through a shock tube, could cause the gunge to be blown >off the filter, and onto the user :-) There is the solution used on some furnaces (and my clothes dryer). There is a whistle that blows if there is enough pressure difference across the filter (lint screen). -don perley perley@trub.crd.ge.com