Avoiding the conversion to 110 Vac seems attractive, but (as has been mentioned above) modern power inverters are more efficient than you might think. The main advantage of reproducing the ac line voltage is the ease of just plugging things in, with no modification to their wiring.
I bought a "Smart UPS 1000", made by APC, on Ebay for $65. To provide 300 V-A (see comment #14 above concerning power factor) for fifteen minutes, this unit uses two 12V sealed lead-acid batteries that weigh about ten pounds apiece, connected in series.
A power supply that ran on 12V would be more versatile (solar cells, vehicle power, etc.). I think a practical approach would be this: switch the 12V through a transformer (higher frequency for a smaller transformer) and rectify it to make around 270Vdc. It would not have to be very well regulated, by power supply standards.
Since monitors and ATX power supplies start out by directly rectifying the line voltage to make 270Vdc, (which they use as the input to their various switching power supply circuits to produce the different output voltages), their line cords can simple be plugged your 270Vdc output. You don't have to worry about polarity, because the full-wave line-voltage rectifiers will direct your 270Vdc properly to their reservoir capacitors.
Thus, you don't need an inverter, and you don't have to listen to the BUZZ of an inverter.
You'd have to check for any line-operated fans in the equipment, though, and replace them with dc fans.
I recall an experimental rig in which you viewed a screen reflected on a flexible plastic membrane stretched over the front of a large woofer. The woofer moved the surface alternately concave and convex, imparting a small, but real, range of front-to-back motion. Different images on the screen had to be synchronized with the movement of the reflecting membrane, and the persistance of vision smeared them into a composite 3d image.
I don't value a person's opinion completely until they learn the basics of grammar, spelling and other elements of good writing.
May I make a couple of suggestions? Thanks.
May I? Thanks.
I don't value a person's opinion until he or she learns the basics of grammar, spelling, and other elements of good writing.
Your condescending tone makes your little error stick out like a wart on a bald head, pal. (Otherwise, I'd be too polite to mention it.)
H-P's first product was an audio sine-wave oscillator based on Hewlett's MSEE thesis at Stanford. He has described how he baked the paint on the front panels in the home oven while his wife was gone, and how Walt Disney Studios gave them their first order for 8 oscillators, which financed them to make more. But nobody here has yet mentioned the cleverness of the design, which is something/. readers might appreciate, so let me briefly describe it.
There are many ways to incorporate a tuned circuit in the feedback path of an amplifier to cause it to oscillate. All were well known in the late 40's. The tricky part is to control the amplification: too little, and the sine waves get smaller and disappear; too much, and they get bigger and distorted and finally clip and come out as square waves, or lock up the amplifier altogether. A stable, low-distortion oscillator requires close level control of the feedback, which determines the amplification.
Hewlett found a beautifully simple way to accomplish this within the feedback network itself, without a separate circuit. By applying the output to a resistor with a positive temperature coefficient, when the output level increased, the resistor would heat up, increasing its resistance. A decreasing level would let the resistor cool off, reducing its resistance. Such a resistor in the the right place in the feedback network would provide automatic self-adjustment of the amplification, and thus the possibility of low distortion and constant output level, all without the need to constantly adjust the oscillator.
So where do you get the necessary resistor? It must have sluggish response so it didn't appreciably change over the course of a cycle of oscillation, which would cause distortion. Hewlett's solution was to use the PILOT LIGHT as the gain-control device! He designed the rest of the circuit around the light bulb on the front panel, and achieved a clean, stable sine wave oscillator that required far fewer parts (and fewer precision parts) than previous designs, but performed much better.
When the light bulb lit up over this inventor's head, he took it literally, and the rest is history.
If you rely too much on metaphors and models to base your decisions on then you are going to get burned.
Sometimes you get burned when you rely too little on models. The young obstetrician Semmelweis, around 1840 as I recall, developed a conceptual model to explain why so many women got sick and died after giving birth. The medical establishment ridiculed his crackpot notion and he was ostracized from the most prestigious hospitals.
Semmelweis conjectured that the women were healthy when they entered the hospital, then something made them sick. In particular, something in the hospital made them sick. Conventional wisdom blamed it on bad air or other vaguely defined culprits. Semmelweis came to think that something outside the body came and inhabited it and made it sick; and that disease-causing agent could be transported to another healthy body and would then cause sickness there also. What a lunatic!
Armed with an explicit model, he could put it to experimental test, which he did: one ward of his hospital carried on as usual, while on another ward Semmelweis rocked the boat. He insisted that doctors and students wash their hands after dissecting in the morgue, before they delivered babies in the ward. This outraged the respectable doctors and they avoided the experimental ward and its wacko ritual.
It took twenty years for the handwashing practice to catch on against the opposition of the experts. Women, of course, caught on immediately. Semmelweis' much-reduced mortality rate made his obstetrical service the busiest as well as the safest in town. That pissed off the old guard even more.
The mental baggage that we are unaware of, because it is too common to notice, is what holds us back the most.
When one's conceptual furniture is made explicit, models can be tested, and progress is possible.
Those curious about the shoulders of giants (whereupon we stand) may wish to scope out some of these books:
Atanasoff: Forgotten Father of the Computer by Clark R. Mollenhoff
The First Electronic Computer: The Atanasoff Story by Alice R. & Arthur W. Burks (1989)
Before the Computer: IBM, NCR, Burroughs, and Remington Rand and the Industry They Created, 1885-1956 by James W. Cortada (1993)
Building IBM: Shaping an Industry and Its Technology by Emerson W. Pugh (1995)
Computer: A History of the Information Machine by Martin Campbell-Kelly & Wm. Aspray (1997)
The Computer Comes of Age by Rene Moreau (1986)
The Computer from Pascal to Von Neumann by Herman H. Goldstine (reprinted 1993)
John Von Neuman and the Origins of Modern Computing by William Aspray (1991)
Engines of the Mind: The Evolution of the Computer from Mainframes to Microprocessors by Joel N. Shurkin (1996)
ENIAC: The Triumphs and Tragedies of the World's First Computer by Scott McCartney (1999)
From Memex to Hypertext: Vannevar Bush and the Mind's Machines by James M. Nyce, Paul Kahn (eds.) & Vannevar Bush (1992)
Great Men and Women of Computing by Donald D. Spencer (2nd ed. 1999)
A History of Computing Technology by Michael R. Williams (2nd ed. 1997)
A History of Modern Computing by Paul E. Ceruzzi (1998)
History of Personal Workstations by Adele Goldberg (ed.) (1988)
History of Scientific Computing by Stephen G. Nash (ed.) (1990)
Leo: The Incredible Story of the World's First Business Computer by David Caminer (ed.) (1997)
Makin' Numbers: Howark Aiken and the Computer by I. Bernard Cohen (ed.) (1999)
Out of Their Minds: The Lives and Discoveries of 15 Great Computer Scientists by Cathy A. Lazere, Dennis Elliott Shasha (1998)
Remembering the Future: Interviews From Personal Computing World by Wendy M. Grossman (1997)
The Timetable of Computers: A Chronology of the Most Important People and Events in the History of Computers by Donald D. Spencer (2nd ed. 1999)
Transforming Computer Technology: Information Processing for the Pentagon 1962-1986 by Arthur L. Nordberg, Judy E. O'Neill, & Kerry Freedman (1996)
Turing and the Computer: The Big Idea by Paul Strathem (1999)
When Computers Went to Sea: The Digitization of the United States Navy by David L. Boslaugh (1999)
Ada, the Enchantress of Numbers: A Selection from the Letters of Lord Byron's Daughter and Her Description of the First Computer by Betty A. Toole (ed.) (1998)
A.M. Turing's ACE Report of 1946 and Other Papers (Charles Babbage Institute Reprint Series for the History of Computing, Vol. 10) by Alan Turing, et al. (1986)
A Bibliographic Guide to the History of Computing, Computers, and the Information Processing Industry by James W. Cortada (1990)
A Bibliographic Guide to Computer Applications, 1950-1990 by James W. Cortada (1996)
Business Builders in Computers by Nathan Aeseng (1999)
Glory and Failure: The Difference Engines of Johann Muller, Charles Babbage, and Georg and Edvard Scheutz (History of Computing) by Michael Lindgren; Craig G. McKay (translator) (1990)
You can cool a canful quickly by laying it on its side in a dish of crushed ice and spinning it. This keeps the cooled liquid from hanging around the cool surface and blocking warmer fluid from coming in direct contact with the cold aluminum.
Roughly five years ago, somebody in Iowa patented an ice-cooled motorized horizontal can rotator that brings a beer or coke down to drinking temp. in the time of a couple TV commercials.
The guy's peltier cooler would work better if he 1) better insulated the can from the ambient air (locally heated by the output side of the Peltier junction), and 2) contrived to circulate the fluid somehow.
The one thing I don't get is, what's the Alpha for?
This was a hot topic in the winter of '98 when Celerons first made dual-processor systems cheap. Check out these informative discussions if you missed them:
This device will be useful in research even if it never pans out in a therapeutic application.
As ghoulish as it sounds, putting 700 Volts across a person's head can sometimes save a life. I speak of electroconvulsive shock therapy for severe depression that has not responded to less drastic treatments.
Somehow, the shock blasts open the blood-brain barrier and changes the brain chemistry toward the normal state. It sounds as if this new technique will permit the investigation of this phenomenon in individual cells, apart from the confusing complexity of the whole brain. It would be great to get beyond mere educated guesses about what's going on here.
The overuse of electroshock in the 50's and 60's has been justly criticized. It was the next big psychiatric fad after prefrontal lobotomy, compared to which, electroconvulsive therapy seemed conservative. It's a crude thing to do to the delicate brain, but if I were morbidly depressed (25% mortality rate), I'd be grateful (afterwards) if somebody zapped me.
Now that their JFS is freed software, perhaps IBM would bankroll a defense of the GPL if a competing company tries to take the code private again (a la BSDL).
I used to wonder why a split-up was considered a remedy, since the ownership would stay the same. The Slashdot interview with antitrust lawyers shortly after the ruling last fall clarified this.
After a forced breakup, the principal officers of the company can work and hold stock in only one of the subentities, under scrutiny of the court.
One of the antitrust lawyers, in the special/. article a few days after the ruling last fall, said that in a forced breakup, each principal can work and hold stock in only one of the resulting subentities (in this case, Baby Bills). Otherwise, there'd be no incentive to change anything. It would be scrutinized by the court, so a 'consultant' arrangement probably would not fly.
Of course the requirement of putting your invention in the open is good, but why the protection?
The protection is the incentive to disclose the invention, instead of keeping it secret. The government encourages disclosure to "...promote the useful arts..."
The trouble with the purificationist position is that the world can never be pure enough to eliminate problems. No matter how many heads roll, there always remain additional sources of contamination.
Self-Censorship: If children have no expectation of privacy at the library's web terminals, it would go a long way toward limiting their viewing of porn, without directly raising First Amanedment issues.
Until the craze for URL-filtering burns itself out (I'm not holding my breath), it might be possible to make the filtering less monolithic and arbitrary. What Republican would publicly oppose free-market competition? Let the filtering lists compete!
Let the hard core guys maintain their own list and cull out everything that would dilute their category. The list would be downloadable from their trade association, to save their customers' time.
Let the mainstream skin purveyors keep the kinkier stuff off their own list. And Playboy could make sure that consumer merchandise is always closely associated with images of bare titties, to keep the economic ball rolling.
The need to maintain the Christian Coalition list would give lots of smug prigs the cover they need to justify their own porn viewing. I really shouldn't criticize these people, because, after all, it was to appease them that President Bush installed the only serious porn conoisseur we have on the Surpreme Court: Clarence Thomas, who Bush called "the most qualified person in the country".
The American Public Health Association could make sure that information sites on their list remained accessible.
The American Civil Liberties Union could have a free-speech list of sites erroneously included by the censors in their porn lists. The constant attempt by the right-wingers to conflate birth control, freedom, etc. with Evil Sex would be easy to expose by daily comparing the lists.
You get the idea. People with a stake in differest aspects of the "problem" would have an incentive to avoid category error in their own lists.
Comparing the lists would easily disclose the abuses of classification. Then the American Library Association, in their wisdom and experience, could decide how to use the lists in a constitutionally acceptable manner. Individuals could download their preferreed list for filtering at home.
Arno Penzias (Nobel Prize winner for radio astronomy) said something, in a speech a couple years ago that I saw on CSPAN, that is relevant to Slashdot.
For most of human history, the ability to REMEMBER confered the greatest advantage. But now, it is so easy to store information, Penzias said, that the ability to FORGET has become more valuable. To cope with information overload, one must learn to SKIM and discard what is trivial while staying alert to what is significant.
Boy, the Slashdot reader has a great opportunity to practice that!
When I moderate, I read all the comments and elevate the good stuff from 0 to 1. It's always in there, and I always wish I had more points to award. I often wish I could give some comments two points to bring them to more people's attention.
I find that comments with high ratings are only rarely superior. And all the complaints about moderation suggest to me that a lot of readers are not adept at skimming for pearls. The moderation system can help, but ultimately you have develop the ability to discard the crap yourself if you want find much signal in the noise.
Here's a chance to start telling the non-technical public about alternatives to M$. This promises Intel marketing as the host, without the usual M$ parasite inside.
(I apologize in advance for referring to a suit buzzword that I had hoped would disappear with the 90's. In the 70's, it was "the bottom line". In the 80's, it was "world class". In the 90's, it was "branding").
How does the Linux movement "brand" a product? If Intel is eager for M$ alternatives, it would probably be willing to apply something besides the 'Windows' sticker next to its "Intel Inside" logo.
The Linux distributions have their brands, but what about generic Linux? We need to make some dynamite graphics available to help turn anti-M$ sentiment specifically in the Linux direction.
Last week I spent several hours trying out chairs at the Herman Miller and Steelcase showrooms. I was surprised to find that both the Miller Aeron Chair and the Steelcase Leap Chair (their Aeron-killer) had broken adjustment controls and were of cheap plastic construction (Aeron: barely adequate; Leap: hopelessly flimsy). In fact, the Steelcase dealer wouldn't even show me the Leap chair until he first demonstrated the older Criterion, so I wouldn't get a bad first impression.
There is a useful book, Compute In Comfort, by Paul Linden, a phys. ed. Ph.D. and martial artist who has intensively studied movement and posture. His main rap is that you can greatly reduce stress by becoming aware of how your body feels, and adjusting your position so that your skeleton carries the weight directly (good posture), instead of having weight hanging off-axis, held by constant muscle tension (bad posture). This balancing is achieved by the proper pelvic tilt, which controls the curvature of the lower back. He advises sitting on different wedge-shaped pads to feel how relaxing it is to the back when you find the best seat angle. Since you need to change position, you need to change seat angle. Linden claims that this is the most important parameter in a chair. To remain comfortable longer, the shape of your back should be established by the angle of the seat, not just the chair back.
Of the current Herman Miller and Steelcase lines, only the Criterion lets you tilt the seat as desired and then lock it at that angle. The Aeron and Leap chairs let the seat tilt down-in-front, for leaning forward, but lock in only two positions.
One thing to consider is that the older chairs are much more solidly built, so you could get a used one and still expect a long life from it. I found broken plastic parts and broken seat tilt locks on both top-of-the-line all-plastic chairs, Aeron and Leap, this despite the Aeron's twelve-year warranty.
Here are my observations:
Aeron (Herman Miller): Very confortable to lean back in- doesn't tend to pull your shirt out or create pressure under the thighs due to its sophisticated linkage system with the main pivot near the knees. Three sizes. Arms adjust to different heights and different angles in the horizontal plane, but arm-arm distance is fixed. Lumbar pad slides up and down; plastic was worn and it wouldn't stay put. Seat tilt locks in normal or forward position (except it didn't work). Back tilt can be set to stop at choice of three angles. Seat is woven material in tension, like a hammock; very comfortable lack of pressure spots, but pelvic tilt is undeterministic. $750.
Equa 2 (Herman Miller): Very comfortable and strongly constructed. A contender. Three sizes. Seat and back are one-piece fiberglass shell, seat and back flex independently, providing support in different sitting positions. Arms adjust in height, spacing, and angle. Inflatable lumbar support adjustable up-and-down. Main seat pivot is near the knees. Can be locked in upright position. Also available as simpler bent-tube-frame model.
Leap (Steelcase): Their answer to the Aeron. Of surprisingly thin plastic construction. Flexible one-piece plastic back has adjustable curvature for low back firmness control, but it wouldn't lock in place. Front of seat can tilt down for sitting forward, but this control also was broken. Arms adjust in height, spacing, and angle, but rattled around a bit in locked position. Salesman didn't want to tell me how much they were asking for this turkey.
Criterion (Steelcase): Very comfortable and strong. Seat can be locked at any desired tilt angle; so can back. Back adjusts up-down and seat adjusts forward-back for perfect fit. Couldn't crank the recliner spring as stiff as I would like. Arms adjust in height and spacing, but not angle. One size. A strong contender.
Sensor (Steelcase): Quite comfortable, solid, older design. Three sizes. Back adjusts up-down, different recline limit stops. Contoured seat tilts from center. Arms adjust in height, apacing, not angle. Also needs a stiffer spring for reclining.
The goal of the patent system is to disseminate knowledge of how things work, in order to promote technological progress. In return for revealing all the essential details of an invention (so that every interested person can study the patent and learn the technology), the Constitution grants the inventor a monopoly on the invention for a period of time.
The legal monopoly is an incentive to REVEAL, and only indirectly an incentive to create. One might be financially motivated to invent something, and keep its workings a trade secret: in this case the patent laws are irrelevant.
This bears on the differences between patents and copyrights. A copyrighted creation is obviously what it is. Protection as a trade secret is impossible. There is no internal technology to reveal, only the work itself; and so books and music are copyrighted, not patented. The creation is independent of the particular medium used for its publication. (An intermediate category is the "design patent", which covers particular embodiments of decorative designs, but that doesn't apply to technical software).
Software doesn't exactly fit within the traditional purview of patents (I mean "utility patents" covering physical inventions, not design patents). Like a literary creation, the source code to a program reveals it completely, so is this respect programs should be protectable by copyright. But a program can't be used directly the way a novel can be read. Like a musical score, a program must direct some other process before there is any useful output. In this respect, since music is copyrighted, programs should also be copyrighted.
But, alas, copyrights last for 75 years beyond the creator's death (and Disney is lobbying hard to get Congress to let them renew the monopoly for another 75 years after that! Semper Mickey). The goal of the patent act (promotion of technical progress), would certainly not be served if software received a 75 year copyright monopoly.
Neither the patent system nor the copyright system provides an obviously appropriate legal framework for software.
In view of this complexity, I agree with Stallman that it is misleading to conflate all these categories into the generic term "intellectual property".
If you're not pushing the overclocking envelope, how do you get satisfactory cooling without resorting to Peltier cells or refrigerators?
I'm making a dual celery box (300A @ 450 MHz) and I've been surprised by the almost Luddite state of ventilation technology in the PC industry. Apparently, conventional practice is to put a fan near each processor's heat sink, and maybe also near the video card and main board chip, and to let the power supply's fan blow the hot air out of the box (perhaps with auxillary fans blowing in or out). No attention seems to be paid to heat accumulation toward the top of the typical case, except that the power supply is usually there, and most of them have their fans blowing toward the exterior (opposite the ATX specification). If the processor gets too hot, the conventional approach seems to be to blow more hot air over it with a more powerful fan. The overall flow through the case seems pretty haphazard.
So the first obvious step is to blow outside air at the heatsinks, not the heated air within the case. I found that Intel has recently promulgated a new spec. to accomplish this in ATX and micro-ATX systems. Described here, it entails a wide, flat duct over a horizontal fan that sits above the processor boards. Air is sucked from outside the case, through the duct, to the fan, and onto the hot corner of the ATX board where the processors, memory, and board chipset lie. They claim it will also cool the AGP video card nearby.
That should help, but what about the hot air in the case? I've decided to make a box with an extra panel inside, an inch and a half from the side panel and parallel to it, forming an air plenum separate from the main volume of the box. I plan to run ducts from this plenum to each hot spot, mostly enveloping the heatsinks, and perhaps also to the hard drives and power supply. This way I can blow air into the plenum and cool everything, with exhaust holes mostly around the top of the case. Yes, this is a parallel resistor network, and it will be necessary to tinker with the duct sizes to balance the flows according to the heat produced in the different locations.
I hope this will let me dispense with multiple fans in the case, and instead have one substantial squirrel-cage blower for the plenum. If you've read this far, it has probably already occurred to you that you could attach a hose to such a case and put the blower ELSEWHERE, to quiet things down. It might also be quieter due to the more laminar airflow (less turbulance).
Alternatively, one could SUCK from the plenum, with air entry holes strategically located in the outer case (e.g., in the front panel above and below the hard drives, etc.). This would be even better, since the heated air would be evacuated from the case directly, and in the summer it could be vented outside the room.
Has anyone gone to such lengths to achieve quiet, effective cooling?
On another note, what about heat pipes? Seen any lately? About fifteen years ago, I fixed an audio power amplifier for an EE who usually attempted his own repairs, but was left scratching his head at this tiny, futuristic, limited-production "concept amp" from Sony. (It's no wonder why: there was no signal voltage until the output stage- it was a current amp, not a voltage amp; quite unusual at the time). This amp had the output transistors on a small copper block, with a copper tube running to the rear, where it ran through a long stack of thin aluminum plates spaced about a quarter inch apart from each other. This was a heat pipe. The tube was concentric and full of refrigerant, which was boiled by the power transistors, forced through one tube as a gas, and condensed to liquid as it flowed through the heat exchanger plates at the rear. The heat input caused the circulation. This allowed the power transistors to be located on a small board with the other circuits, without heating them up very much. Other components could sit right on top of the thin power amp chassis without getting hot. The whole thing was almost weightless, but each channel put out 125 Watts. (It also had a rectified-line switching power supply to eliminate the power transformer).
Now, that was COOL. Why don't Intel and Alpha owners have heat pipe coolers like that? It makes the status quo look pretty retro, if you ask me.
Slashdot Mirror
Avoiding the conversion to 110 Vac seems attractive, but (as has been mentioned above) modern power inverters are more efficient than you might think. The main advantage of reproducing the ac line voltage is the ease of just plugging things in, with no modification to their wiring.
I bought a "Smart UPS 1000", made by APC, on Ebay for $65. To provide 300 V-A (see comment #14 above concerning power factor) for fifteen minutes, this unit uses two 12V sealed lead-acid batteries that weigh about ten pounds apiece, connected in series.
A power supply that ran on 12V would be more versatile (solar cells, vehicle power, etc.). I think a practical approach would be this: switch the 12V through a transformer (higher frequency for a smaller transformer) and rectify it to make around 270Vdc. It would not have to be very well regulated, by power supply standards.
Since monitors and ATX power supplies start out by directly rectifying the line voltage to make 270Vdc, (which they use as the input to their various switching power supply circuits to produce the different output voltages), their line cords can simple be plugged your 270Vdc output. You don't have to worry about polarity, because the full-wave line-voltage rectifiers will direct your 270Vdc properly to their reservoir capacitors.
Thus, you don't need an inverter, and you don't have to listen to the BUZZ of an inverter.
You'd have to check for any line-operated fans in the equipment, though, and replace them with dc fans.
Ted Nelson patented the hyperlink in 1960.
/. discussion, but I'm TLTLIU.)
(as I recall, it was linked to in a recent
I recall an experimental rig in which you viewed a screen reflected on a flexible plastic membrane stretched over the front of a large woofer. The woofer moved the surface alternately concave and convex, imparting a small, but real, range of front-to-back motion. Different images on the screen had to be synchronized with the movement of the reflecting membrane, and the persistance of vision smeared them into a composite 3d image.
I don't value a person's opinion until he or she learns the basics of grammar, spelling, and other elements of good writing.
Your condescending tone makes your little error stick out like a wart on a bald head, pal. (Otherwise, I'd be too polite to mention it.)
Looks like you could balance a camera in the sphere and move it around, requiring a minimum of reaction force.
H-P's first product was an audio sine-wave oscillator based on Hewlett's MSEE thesis at Stanford. He has described how he baked the paint on the front panels in the home oven while his wife was gone, and how Walt Disney Studios gave them their first order for 8 oscillators, which financed them to make more. But nobody here has yet mentioned the cleverness of the design, which is something /. readers might appreciate, so let me briefly describe it.
There are many ways to incorporate a tuned circuit in the feedback path of an amplifier to cause it to oscillate. All were well known in the late 40's. The tricky part is to control the amplification: too little, and the sine waves get smaller and disappear; too much, and they get bigger and distorted and finally clip and come out as square waves, or lock up the amplifier altogether. A stable, low-distortion oscillator requires close level control of the feedback, which determines the amplification.
Hewlett found a beautifully simple way to accomplish this within the feedback network itself, without a separate circuit. By applying the output to a resistor with a positive temperature coefficient, when the output level increased, the resistor would heat up, increasing its resistance. A decreasing level would let the resistor cool off, reducing its resistance. Such a resistor in the the right place in the feedback network would provide automatic self-adjustment of the amplification, and thus the possibility of low distortion and constant output level, all without the need to constantly adjust the oscillator.
So where do you get the necessary resistor? It must have sluggish response so it didn't appreciably change over the course of a cycle of oscillation, which would cause distortion. Hewlett's solution was to use the PILOT LIGHT as the gain-control device! He designed the rest of the circuit around the light bulb on the front panel, and achieved a clean, stable sine wave oscillator that required far fewer parts (and fewer precision parts) than previous designs, but performed much better.
When the light bulb lit up over this inventor's head, he took it literally, and the rest is history.
Sometimes you get burned when you rely too little on models. The young obstetrician Semmelweis, around 1840 as I recall, developed a conceptual model to explain why so many women got sick and died after giving birth. The medical establishment ridiculed his crackpot notion and he was ostracized from the most prestigious hospitals.
Semmelweis conjectured that the women were healthy when they entered the hospital, then something made them sick. In particular, something in the hospital made them sick. Conventional wisdom blamed it on bad air or other vaguely defined culprits. Semmelweis came to think that something outside the body came and inhabited it and made it sick; and that disease-causing agent could be transported to another healthy body and would then cause sickness there also. What a lunatic!
Armed with an explicit model, he could put it to experimental test, which he did: one ward of his hospital carried on as usual, while on another ward Semmelweis rocked the boat. He insisted that doctors and students wash their hands after dissecting in the morgue, before they delivered babies in the ward. This outraged the respectable doctors and they avoided the experimental ward and its wacko ritual.
It took twenty years for the handwashing practice to catch on against the opposition of the experts. Women, of course, caught on immediately. Semmelweis' much-reduced mortality rate made his obstetrical service the busiest as well as the safest in town. That pissed off the old guard even more.
The mental baggage that we are unaware of, because it is too common to notice, is what holds us back the most.
When one's conceptual furniture is made explicit, models can be tested, and progress is possible.
Those curious about the shoulders of giants (whereupon we stand) may wish to scope out some of these books:
Atanasoff: Forgotten Father of the Computer
by Clark R. Mollenhoff
The First Electronic Computer: The Atanasoff Story
by Alice R. & Arthur W. Burks (1989)
Before the Computer: IBM, NCR, Burroughs, and Remington Rand and the Industry They Created, 1885-1956
by James W. Cortada (1993)
Building IBM: Shaping an Industry and Its Technology
by Emerson W. Pugh (1995)
Computer: A History of the Information Machine
by Martin Campbell-Kelly & Wm. Aspray (1997)
The Computer Comes of Age
by Rene Moreau (1986)
The Computer from Pascal to Von Neumann
by Herman H. Goldstine (reprinted 1993)
John Von Neuman and the Origins of Modern Computing
by William Aspray (1991)
Engines of the Mind: The Evolution of the Computer from Mainframes to Microprocessors
by Joel N. Shurkin (1996)
ENIAC: The Triumphs and Tragedies of the World's First Computer
by Scott McCartney (1999)
From Memex to Hypertext: Vannevar Bush and the Mind's Machines
by James M. Nyce, Paul Kahn (eds.) & Vannevar Bush (1992)
Great Men and Women of Computing
by Donald D. Spencer (2nd ed. 1999)
A History of Computing Technology
by Michael R. Williams (2nd ed. 1997)
A History of Modern Computing
by Paul E. Ceruzzi (1998)
History of Personal Workstations
by Adele Goldberg (ed.) (1988)
History of Scientific Computing
by Stephen G. Nash (ed.) (1990)
Leo: The Incredible Story of the World's First Business Computer
by David Caminer (ed.) (1997)
Makin' Numbers: Howark Aiken and the Computer
by I. Bernard Cohen (ed.) (1999)
Out of Their Minds: The Lives and Discoveries of 15 Great Computer Scientists
by Cathy A. Lazere, Dennis Elliott Shasha (1998)
Remembering the Future: Interviews From Personal Computing World
by Wendy M. Grossman (1997)
The Timetable of Computers: A Chronology of the Most Important People and Events in the History of Computers
by Donald D. Spencer (2nd ed. 1999)
Transforming Computer Technology: Information Processing for the Pentagon 1962-1986
by Arthur L. Nordberg, Judy E. O'Neill, & Kerry Freedman (1996)
Turing and the Computer: The Big Idea
by Paul Strathem (1999)
When Computers Went to Sea: The Digitization of the United States Navy
by David L. Boslaugh (1999)
Ada, the Enchantress of Numbers: A Selection from the Letters of Lord Byron's Daughter and Her Description of the First Computer
by Betty A. Toole (ed.) (1998)
A.M. Turing's ACE Report of 1946 and Other Papers (Charles Babbage Institute Reprint Series for the History of Computing, Vol. 10)
by Alan Turing, et al. (1986)
A Bibliographic Guide to the History of Computing, Computers, and the Information Processing Industry
by James W. Cortada (1990)
A Bibliographic Guide to Computer Applications, 1950-1990
by James W. Cortada (1996)
Business Builders in Computers
by Nathan Aeseng (1999)
Glory and Failure: The Difference Engines of Johann Muller, Charles Babbage, and Georg and Edvard Scheutz
(History of Computing)
by Michael Lindgren; Craig G. McKay (translator) (1990)
For a book review and discussion from last October, see: A History of Modern Computing
You can cool a canful quickly by laying it on its side in a dish of crushed ice and spinning it. This keeps the cooled liquid from hanging around the cool surface and blocking warmer fluid from coming in direct contact with the cold aluminum.
Roughly five years ago, somebody in Iowa patented an ice-cooled motorized horizontal can rotator that brings a beer or coke down to drinking temp. in the time of a couple TV commercials.
The guy's peltier cooler would work better if he 1) better insulated the can from the ambient air (locally heated by the output side of the Peltier junction), and 2) contrived to circulate the fluid somehow.
The one thing I don't get is, what's the Alpha for?
Ask Slashdot: Is SMP Worth It?
Ask Slashdot: What's a Good Motherboard for SMP Linux?
Ask Slashdot: Building an Upgradable Dual Processor System
This device will be useful in research even if it never pans out in a therapeutic application.
As ghoulish as it sounds, putting 700 Volts across a person's head can sometimes save a life. I speak of electroconvulsive shock therapy for severe depression that has not responded to less drastic treatments.
Somehow, the shock blasts open the blood-brain barrier and changes the brain chemistry toward the normal state. It sounds as if this new technique will permit the investigation of this phenomenon in individual cells, apart from the confusing complexity of the whole brain. It would be great to get beyond mere educated guesses about what's going on here.
The overuse of electroshock in the 50's and 60's has been justly criticized. It was the next big psychiatric fad after prefrontal lobotomy, compared to which, electroconvulsive therapy seemed conservative. It's a crude thing to do to the delicate brain, but if I were morbidly depressed (25% mortality rate), I'd be grateful (afterwards) if somebody zapped me.
Now that Slashdot has deep pockets, the editors ought to purchase commercial reports like this and spill the beans.
It's no copyright violation if the contents are paraphrased.
Now that their JFS is freed software, perhaps IBM would bankroll a defense of the GPL if a competing company tries to take the code private again (a la BSDL).
I used to wonder why a split-up was considered a remedy, since the ownership would stay the same. The Slashdot interview with antitrust lawyers shortly after the ruling last fall clarified this.
After a forced breakup, the principal officers of the company can work and hold stock in only one of the subentities, under scrutiny of the court.
One of the antitrust lawyers, in the special /. article a few days after the ruling last fall, said that in a forced breakup, each principal can work and hold stock in only one of the resulting subentities (in this case, Baby Bills). Otherwise, there'd be no incentive to change anything. It would be scrutinized by the court, so a 'consultant' arrangement probably would not fly.
Of course the requirement of putting your invention in the open is good, but why the protection?
The protection is the incentive to disclose the invention, instead of keeping it secret. The government encourages disclosure to "...promote the useful arts..."
The trouble with the purificationist position is that the world can never be pure enough to eliminate problems. No matter how many heads roll, there always remain additional sources of contamination.
Self-Censorship: If children have no expectation of privacy at the library's web terminals, it would go a long way toward limiting their viewing of porn, without directly raising First Amanedment issues.
Until the craze for URL-filtering burns itself out (I'm not holding my breath), it might be possible to make the filtering less monolithic and arbitrary. What Republican would publicly oppose free-market competition? Let the filtering lists compete!
Let the hard core guys maintain their own list and cull out everything that would dilute their category. The list would be downloadable from their trade association, to save their customers' time.
Let the mainstream skin purveyors keep the kinkier stuff off their own list. And Playboy could make sure that consumer merchandise is always closely associated with images of bare titties, to keep the economic ball rolling.
The need to maintain the Christian Coalition list would give lots of smug prigs the cover they need to justify their own porn viewing. I really shouldn't criticize these people, because, after all, it was to appease them that President Bush installed the only serious porn conoisseur we have on the Surpreme Court: Clarence Thomas, who Bush called "the most qualified person in the country".
The American Public Health Association could make sure that information sites on their list remained accessible.
The American Civil Liberties Union could have a free-speech list of sites erroneously included by the censors in their porn lists. The constant attempt by the right-wingers to conflate birth control, freedom, etc. with Evil Sex would be easy to expose by daily comparing the lists.
You get the idea. People with a stake in differest aspects of the "problem" would have an incentive to avoid category error in their own lists.
Comparing the lists would easily disclose the abuses of classification. Then the American Library Association, in their wisdom and experience, could decide how to use the lists in a constitutionally acceptable manner. Individuals could download their preferreed list for filtering at home.
Arno Penzias (Nobel Prize winner for radio astronomy) said something, in a speech a couple years ago that I saw on CSPAN, that is relevant to Slashdot.
For most of human history, the ability to REMEMBER confered the greatest advantage. But now, it is so easy to store information, Penzias said, that the ability to FORGET has become more valuable. To cope with information overload, one must learn to SKIM and discard what is trivial while staying alert to what is significant.
Boy, the Slashdot reader has a great opportunity to practice that!
When I moderate, I read all the comments and elevate the good stuff from 0 to 1. It's always in there, and I always wish I had more points to award. I often wish I could give some comments two points to bring them to more people's attention.
I find that comments with high ratings are only rarely superior. And all the complaints about moderation suggest to me that a lot of readers are not adept at skimming for pearls. The moderation system can help, but ultimately you have develop the ability to discard the crap yourself if you want find much signal in the noise.
Here's a chance to start telling the non-technical public about alternatives to M$. This promises Intel marketing as the host, without the usual M$ parasite inside.
(I apologize in advance for referring to a suit buzzword that I had hoped would disappear with the 90's. In the 70's, it was "the bottom line". In the 80's, it was "world class". In the 90's, it was "branding").
How does the Linux movement "brand" a product? If Intel is eager for M$ alternatives, it would probably be willing to apply something besides the 'Windows' sticker next to its "Intel Inside" logo.
The Linux distributions have their brands, but what about generic Linux? We need to make some dynamite graphics available to help turn anti-M$ sentiment specifically in the Linux direction.
You're right about the case designers' disregard of air flow.
I made a box with ducts to each hot spot, allowing the hot air to be exhausted by a remote fan. Much quieter!
It's described toward the end of this Slashdot discussion, comment #61. (Can't just link to the individual comment, unfortunately).
Last week I spent several hours trying out chairs at the Herman Miller and Steelcase showrooms. I was surprised to find that both the Miller Aeron Chair and the Steelcase Leap Chair (their Aeron-killer) had broken adjustment controls and were of cheap plastic construction (Aeron: barely adequate; Leap: hopelessly flimsy). In fact, the Steelcase dealer wouldn't even show me the Leap chair until he first demonstrated the older Criterion, so I wouldn't get a bad first impression.
There is a useful book, Compute In Comfort, by Paul Linden, a phys. ed. Ph.D. and martial artist who has intensively studied movement and posture. His main rap is that you can greatly reduce stress by becoming aware of how your body feels, and adjusting your position so that your skeleton carries the weight directly (good posture), instead of having weight hanging off-axis, held by constant muscle tension (bad posture). This balancing is achieved by the proper pelvic tilt, which controls the curvature of the lower back. He advises sitting on different wedge-shaped pads to feel how relaxing it is to the back when you find the best seat angle. Since you need to change position, you need to change seat angle. Linden claims that this is the most important parameter in a chair. To remain comfortable longer, the shape of your back should be established by the angle of the seat, not just the chair back.
Of the current Herman Miller and Steelcase lines, only the Criterion lets you tilt the seat as desired and then lock it at that angle. The Aeron and Leap chairs let the seat tilt down-in-front, for leaning forward, but lock in only two positions.
One thing to consider is that the older chairs are much more solidly built, so you could get a used one and still expect a long life from it. I found broken plastic parts and broken seat tilt locks on both top-of-the-line all-plastic chairs, Aeron and Leap, this despite the Aeron's twelve-year warranty.
Here are my observations:
Aeron (Herman Miller): Very confortable to lean back in- doesn't tend to pull your shirt out or create pressure under the thighs due to its sophisticated linkage system with the main pivot near the knees. Three sizes. Arms adjust to different heights and different angles in the horizontal plane, but arm-arm distance is fixed.
Lumbar pad slides up and down; plastic was worn and it wouldn't stay put. Seat tilt locks in normal or forward position (except it didn't work). Back tilt can be set to stop at choice of three angles. Seat is woven material in tension, like a hammock; very comfortable lack of pressure spots, but pelvic tilt is undeterministic. $750.
Equa 2 (Herman Miller): Very comfortable and strongly constructed. A contender. Three sizes. Seat and back are one-piece fiberglass shell, seat and back flex independently, providing support in different sitting positions. Arms adjust in height, spacing, and angle. Inflatable lumbar support adjustable up-and-down. Main seat pivot is near the knees. Can be locked in upright position. Also available as simpler bent-tube-frame model.
Leap (Steelcase): Their answer to the Aeron. Of surprisingly thin plastic construction. Flexible one-piece plastic back has adjustable curvature for low back firmness control, but it wouldn't lock in place. Front of seat can tilt down for sitting forward, but this control also was broken. Arms adjust in height, spacing, and angle, but rattled around a bit in locked position. Salesman didn't want to tell me how much they were asking for this turkey.
Criterion (Steelcase): Very comfortable and strong. Seat can be locked at any desired tilt angle; so can back. Back adjusts up-down and seat adjusts forward-back for perfect fit. Couldn't crank the recliner spring as stiff as I would like. Arms adjust in height and spacing, but not angle. One size. A strong contender.
Sensor (Steelcase): Quite comfortable, solid, older design. Three sizes. Back adjusts up-down, different recline limit stops. Contoured seat tilts from center. Arms adjust in height, apacing, not angle. Also needs a stiffer spring for reclining.
If Judge Jackson releases his findings today, will the first person to download it please POST THE WHOLE DOCUMENT HERE?
This will be a public document, unencumbered by copyright, so lets PUT IT HERE and avoid redundant bandwidth hogging.
In this case, the responsible course of action is for Slashdot to be a broadcaster.
The goal of the patent system is to disseminate knowledge of how things work, in order to promote technological progress. In return for revealing all the essential details of an invention (so that every interested person can study the patent and learn the technology), the Constitution grants the inventor a monopoly on the invention for a period of time.
The legal monopoly is an incentive to REVEAL, and only indirectly an incentive to create. One might be financially motivated to invent something, and keep its workings a trade secret: in this case the patent laws are irrelevant.
This bears on the differences between patents and copyrights. A copyrighted creation is obviously what it is. Protection as a trade secret is impossible. There is no internal technology to reveal, only the work itself; and so books and music are copyrighted, not patented. The creation is independent of the particular medium used for its publication. (An intermediate category is the "design patent", which covers particular embodiments of decorative designs, but that doesn't apply to technical software).
Software doesn't exactly fit within the traditional purview of patents (I mean "utility patents" covering physical inventions, not design patents). Like a literary creation, the source code to a program reveals it completely, so is this respect programs should be protectable by copyright. But a program can't be used directly the way a novel can be read. Like a musical score, a program must direct some other process before there is any useful output. In this respect, since music is copyrighted, programs should also be copyrighted.
But, alas, copyrights last for 75 years beyond the creator's death (and Disney is lobbying hard to get Congress to let them renew the monopoly for another 75 years after that! Semper Mickey). The goal of the patent act (promotion of technical progress), would certainly not be served if software received a 75 year copyright monopoly.
Neither the patent system nor the copyright system provides an obviously appropriate legal framework for software.
In view of this complexity, I agree with Stallman that it is misleading to conflate all these categories into the generic term "intellectual property".
If you're not pushing the overclocking envelope, how do you get satisfactory cooling without resorting to Peltier cells or refrigerators?
I'm making a dual celery box (300A @ 450 MHz) and I've been surprised by the almost Luddite state of ventilation technology in the PC industry. Apparently, conventional practice is to put a fan near each processor's heat sink, and maybe also near the video card and main board chip, and to let the power supply's fan blow the hot air out of the box (perhaps with auxillary fans blowing in or out). No attention seems to be paid to heat accumulation toward the top of the typical case, except that the power supply is usually there, and most of them have their fans blowing toward the exterior (opposite the ATX specification). If the processor gets too hot, the conventional approach seems to be to blow more hot air over it with a more powerful fan. The overall flow through the case seems pretty haphazard.
So the first obvious step is to blow outside air at the heatsinks, not the heated air within the case. I found that Intel has recently promulgated a new spec. to accomplish this in ATX and micro-ATX systems. Described here, it entails a wide, flat duct over a horizontal fan that sits above the processor boards. Air is sucked from outside the case, through the duct, to the fan, and onto the hot corner of the ATX board where the processors, memory, and board chipset lie. They claim it will also cool the AGP video card nearby.
That should help, but what about the hot air in the case? I've decided to make a box with an extra panel inside, an inch and a half from the side panel and parallel to it, forming an air plenum separate from the main volume of the box. I plan to run ducts from this plenum to each hot spot, mostly enveloping the heatsinks, and perhaps also to the hard drives and power supply. This way I can blow air into the plenum and cool everything, with exhaust holes mostly around the top of the case. Yes, this is a parallel resistor network, and it will be necessary to tinker with the duct sizes to balance the flows according to the heat produced in the different locations.
I hope this will let me dispense with multiple fans in the case, and instead have one substantial squirrel-cage blower for the plenum. If you've read this far, it has probably already occurred to you that you could attach a hose to such a case and put the blower ELSEWHERE, to quiet things down. It might also be quieter due to the more laminar airflow (less turbulance).
Alternatively, one could SUCK from the plenum, with air entry holes strategically located in the outer case (e.g., in the front panel above and below the hard drives, etc.). This would be even better, since the heated air would be evacuated from the case directly, and in the summer it could be vented outside the room.
Has anyone gone to such lengths to achieve quiet, effective cooling?
On another note, what about heat pipes? Seen any lately? About fifteen years ago, I fixed an audio power amplifier for an EE who usually attempted his own repairs, but was left scratching his head at this tiny, futuristic, limited-production "concept amp" from Sony. (It's no wonder why: there was no signal voltage until the output stage- it was a current amp, not a voltage amp; quite unusual at the time). This amp had the output transistors on a small copper block, with a copper tube running to the rear, where it ran through a long stack of thin aluminum plates spaced about a quarter inch apart from each other. This was a heat pipe. The tube was concentric and full of refrigerant, which was boiled by the power transistors, forced through one tube as a gas, and condensed to liquid as it flowed through the heat exchanger plates at the rear. The heat input caused the circulation. This allowed the power transistors to be located on a small board with the other circuits, without heating them up very much. Other components could sit right on top of the thin power amp chassis without getting hot. The whole thing was almost weightless, but each channel put out 125 Watts. (It also had a rectified-line switching power supply to eliminate the power transformer).
Now, that was COOL. Why don't Intel and Alpha owners have heat pipe coolers like that? It makes the status quo look pretty retro, if you ask me.