I remember a TV many years ago, perhaps late 90's or early 2k, which booted with a common Award BIOS screen and RAM check. I think we sold exactly one (and that one was the display model).
It was a useless device. Despite having a high-res CRT display with decent color, and a line doubler (which was potentially way cool in those pre-HDTV/DVI/HDMI times), it sucked: It irrevocably upscaled the output of a PSX, and the result was double-ugly instead of double-smooth since it got the field order precisely wrong.
I theorize that the magnet is polarized with one end being north, and the other being south (instead of one flat side being north, and the other side being south).
This fits well with my understanding of voice coils, as well: If it were polarized in any other direction, the head stack wouldn't move in a useful axis.
So, covering one entire flat side of it will short the magnetic field on that side. Whether it's completely shorted or not is not important -- the field is still easily demonstrated to be extremely weak on the other side of whatever that backing plate is made from, while concurrently amusingly strong on the other side, and all that differentiates the two sides is a fairly thin bit of mostly-flat, stamped sheet metal.
Meanwhile, the more I read about Mu-metal proper, the more I doubt that this is the same exact material (it primarily has to withstand the stress of a busy and relatively massive headstack - magnetic shielding is obviously secondary), but there's obviously a myriad of other metallurgical alternatives which perform the role of short-circuiting better than mild steel...
As to re-annealing: Wouldn't raising the temperature above the Curie point be adequate? Or is that merely synonymous in magnetic parlance with "re-annealing"?
I love the two-handed pointer, with dedicated modifier keys (which resemble piano keys in their size and pivoting movement) under the left hand, and the pointer itself under the right.
It might be said that this layout was copied, much later, as the common control mechanism for PC-based first-person games (ASFW keys under left hand, mouse in right).
There is a T1 global back-bone that sells dedicated internet bandwidth at a flat rate of $1/mbit/month in 10gbit increments. That's about $1 for 316GB(bytes)/month. I'm sure a T1 ISP gets it cheaper than that.
The TV whines at about 15kHz. It's not out-of-spec, but just a loose winding on the flyback transformer. No big deal.
I can't hear it much anymore except in extreme cases, but when I was a kid it'd drive me nuts. I could walk by houses on a quiet night and tell without looking if they had a TV on, or if they had more than one on (as long as they were tuned to different channels -- the slight difference in frequency would cause the sound to heterodyne).
The dishwasher is just an appliance, not a structural item. How many screws hold the washing machine, clothes drier, fridge, or tank water heater in place?
The two screws are just there to keep the thing from tipping forward annoyingly when the racks are all the way out. They're perfectly adequate for this role (actually, one screw in the right spot would be adequate -- three points define a plane...).
I've seen children swing from cabinet doors, teenagers slam them with wild abandon, and homeowners who don't know how to tighten a screw when things get wonky with time. I've seen top dollar decks rot from general lack of maintenance. And I've seen folks who are unqualified to hang anything on any wall, because the first thing they do is reach for a hammer and a nail, and when that doesn't work, they find a bigger hammer.
My house has some drywall that is 50 or 60 years old, just 3/8" thick, and brittle. It holds stuff just fine, provided that appropriate fasteners are used in appropriate ways. It's not rocket surgery.
Some people try to take care of their things. Some people don't think they have time to figure out how. The former group is proud of their collection of tools and earned experience. The latter bemoans every failure as being someone else's problem without ever considering if there were something they could have done differently.
A Faraday cage does little or nothing when faced with a static magnetic field.
At RF frequencies, it does work fine. But there's a world of difference between (essentially) DC and a few hundred KHz. Think of it as series inductance creating a low-pass filter.
Come to think of it, I'd not be surprised in the slightest if a Faraday cage performed exactly like an inductor, complete with a first-order slope...
(Please note that I'm considering the claim that they've experienced a hard drive failure to be a coincidence.)
True... but the sheet steel used to form the case of almost all PCs would provide very good magnetic shielding.
Flat sheet steel does little to curb static magnetic fields.
Experiment: Find a CRT, and a magnet. Observe how they behave together. Next, put something steel (the side from a PC case?) between the two, and observer that they behave almost the same... Feel free to repeat with iron filings, aluminum and steel cans, old license plates, or whatever. It shields somewhat, and does a bit of scattering, but it's lousy (and certainly not "very good").
One can use an appropriately curved chunk of curved steel to accomplish some shielding. See, for instance, shielded speakers, which use a cup to completely surround the magnet, sometimes in addition to a second magnet which is only used to help counteract the external field of the first.
But, you know, your PC case isn't shaped like that.
There are certain high-permeability materials (Mu-metal being one) which do far better, but they're pretty far removed from the common mild steel of a PC. (I haven't verified this, but I've read that Mu-metal is used on the back side of the neodymium magnets inside of a hard drive, and if that is the case it would easily explain how one side sticks ferociously to the side of the fridge, and the other side won't even pick up a paper clip.)
CRTs (whether televisions, computer monitors, or vector displays) are easily influenced by magnetic fields, both static and otherwise. They operate using magnets, and it doesn't take much to disturb appreciably disturb them.
That said: Bad wiring, in and of itself, doesn't make for radio interference. The singular exception to this is when there is arcing. But if that were the case the place would've likely already burned, or the fault would otherwise have destroyed/fixed itself, or at least things would smell funny on a regular basis...and you'd literally see arcing on analog TV broadcasts, in the form regularly-occurring horizontally-aligned lines of static.
So, it's probably not arcing. But bad electronics and other noisy loads can cause all kinds of interference, however.
The usual culprits are lamp dimmers and fluorescent ballasts, ugly switching supplies, and motors with bad brushes. Any noise generated by stuff like this will radiate throughout (and around) the house.
And. It may not even be a problem inside the house: It might be the neighbor down the way, or a near(ish) farm or factory sharing the same leg. I mean: Your folks don't exactly have their own generating station, so whatever comes down the wire from outside is also going to radiate inside.
If you're really curious about it, turn things off at their place one by one (either by unplugging them, or perhaps at the breaker panel in the case of dimmer-equipped lighting circuits and fixed equipment like the furnace and the dishwasher) until you narrow the problem down to a specific device which verifiably causes it, and then repair or replace that item.
And if it's still noisy with literally everything off, the problem is not within the house. (There's ways to overcome that, as well, if it's important. My guess is that it's not important.)
Useless anecdote: I was sure I had a wiring fault, grounding issue, bad plugs/wires/coil/distributor, or something else wrong in my work truck, since AM reception was totally hosed no matter where I was driving...though FM worked quite well. I ignored it for a long while since I didn't listen to AM much anyway. One day, on a whim, I pulled the cell phone charger out of the dashboard socket and -instantly- the AM reception went from "meh" to relatively awesome. And that's just a little DC-DC converter. (The charger subsequently died in a fire, just to ensure nobody else would ever find it and try to use it.)
And more useless information: Analog (NTSC) broadcast television uses AM for video, and FM for audio.
CRTs are affected by even the magnetism of the Earth, and will change ("distort") depending on their relative orientation. Better CRT displays, from back in the day at least, have a control (commonly labeled "rotation") to help offset this exact problem.
Remember, CRTs work with magnetic fields: One might even say that all a CRT does is visualize magnetism. If any outside force changes those fields, the resultant picture will change accordingly and measurably.
That said: I've had static magnetic fields of unknown origin mess with TVs before. I suspect it was an iron counterweight for a window sash causing the issue, but was never sure, since I simply moved the TV and the problem went away.
I don't think I'd ever be lawyering up to go head-to-head with a builder over such an issue unless the kitchen knives had a hard time staying in the drawer, and the fillings were getting sucked out of my teeth.
And even then, as others have pointed out, it's easy to degauss steel: Wrap a welding lead around it, and turn the welder on. Bonus points for gradually reducing amperage to maximize results.
At worst, this entails the builder borrow an arc welding kit from somewhere, and pay someone to patch and paint some drywall. No big deal, and certainly a lot cheaper than a few hours with a lawyer. If it's not part of the contract, and it's a really big deal for some reason, then being reasonable ("OK, Mr. Builder, you degauss this beam and fix the drywall, I'll paint it and clean up") would have probably gone a long way...
I frequently give positive moderation to unpopular opinions that even I don't agree with, if the logic behind them is sane and the human reasoning seems genuine. Especially if the comment also brings new facts to a discussion.
I cannot imagine that I am the only person with mod points to adopt this behavior.
The timing belt of a Kia is tensioned by the water pump which is mounter in an eccentric housing. Mechanic tensions the belt by turning the housing with his left hand, tightens bolt with right. Belt stays tight until it stretches.
I'm not sure how much of a big deal that really is, unless it's easy to jump timing when changing a water pump out.
IIRC, timing belts these days are reinforced with Kevlar. They should not stretch appreciably, but they will wear out eventually. Replace it at the specified interval (40k or 60k depending on the Kia), tighten things properly at that time, and call it done until the next replacement interval.
The saw spins up in about a quarter-second second, and dims the lights for a moment. It takes about two seconds to stop, and does not dim the lights at that time.
This is far more indicative of resistive braking than of reversing the motor.
It's also simpler, cheaper, and has fewer parts to wear out. And since the saw was very cheap, I'm inclined to believe that its brake is also very cheap.
If you want to program a windows phone you're going to need an OS from "a specific manufacturer."
And I can run that specific OS on commodity hardware. I don't have to use a computer that is built by Microsoft.
And again, if you're making a serious app then buying a computer to develop it on is something you're probably going to do anyway.
I like choices when buying hardware. While I believe that Apple produce very fine hardware indeed, I very much enjoy the freedom to choose other manufacturers. Today's box for developing a "serious app" is going to be tomorrow's box for tinkering with hardware, and I like tinkering with hardware and stretching my dollars as far as I can.
Oh, and I bet all your machines (or at least the ones you can actually write anything for a major smartphone on) all have processors from one of two manufacturers.
I've always tried to put my money into the underdog CPUs whenever possible, whether that be Cyrix/IBM (6x86MX), or even IDT, as long as they worked with common industry standard parts. There was a period in the early-mid 90's where DEC's Alpha had potential to be real and hackable alternative. It is very unfortunate that we currently only have two realistic choices.
I care because I don't have a Mac. I do have a bunch of PCs which I can do almost anything else with, though...
There is a plain and definite difference between "needing a computer" and "needing a computer from a specific manufacturer." If you can't detect that difference, then there's really no hope for you.
"Regenerative braking" is just another way to brake (ie: slow down) a moving vehicle, with the benefit of storing some of that energy as electricity. Other common methods using discs or drums lose dissipate all of the energy as heat.
A similar braking system is used on the small(ish) AC-powered compound miter saw that I have, which rapidly stops the blade after releasing the trigger. But instead of using the stored energy of the forward-moving vehicle to charge a battery, it gets dumped through a resistor and converted to heat. It's simple, easy, and cheap: Compared to a saw which does not brake after use, it just requires a slightly fancier switch, a little more wire, and a resistor, since a common AC motor is just a generator running backward (and vice-versa).
Just because it's not mechanically-operated and does not rely on friction to get it done does not mean that it is not a brake.
The Tesla also has disc brakes, and I'm sure it can stop very quickly indeed if directed to do so, which is important on a car. My saw does not have a mechanical brake since it's just a convenience item, and it's OK if it takes a few seconds for it to stop spinning.
If you develop for Windows, you can buy any of a wide array of computers to do the work, from a large number of different manufacturers -- including Apple. You can even build one yourself using common parts that meet industry-standard specifications like ATX.
If you want to develop for an iPhone, you have to have a Mac. Not a Dell, not something you hobbled together with interchangable bits, but an actual Mac.
Slashdot Mirror
Dumb TVs don't have CISC CPUs trying to solve the world's problems.
"Smart" TVs do.
If you can't detect the difference, then there's nothing more for us to discuss on this matter.
I think the anecdote has something to add about the concept of "smart" televisions in general.
I remember a TV many years ago, perhaps late 90's or early 2k, which booted with a common Award BIOS screen and RAM check. I think we sold exactly one (and that one was the display model).
It was a useless device. Despite having a high-res CRT display with decent color, and a line doubler (which was potentially way cool in those pre-HDTV/DVI/HDMI times), it sucked: It irrevocably upscaled the output of a PSX, and the result was double-ugly instead of double-smooth since it got the field order precisely wrong.
It had an Intel CPU.
Is it dead now?
Good.
Thanks!
[/shallow]
Yeah, true.
I theorize that the magnet is polarized with one end being north, and the other being south (instead of one flat side being north, and the other side being south).
This fits well with my understanding of voice coils, as well: If it were polarized in any other direction, the head stack wouldn't move in a useful axis.
So, covering one entire flat side of it will short the magnetic field on that side. Whether it's completely shorted or not is not important -- the field is still easily demonstrated to be extremely weak on the other side of whatever that backing plate is made from, while concurrently amusingly strong on the other side, and all that differentiates the two sides is a fairly thin bit of mostly-flat, stamped sheet metal.
Meanwhile, the more I read about Mu-metal proper, the more I doubt that this is the same exact material (it primarily has to withstand the stress of a busy and relatively massive headstack - magnetic shielding is obviously secondary), but there's obviously a myriad of other metallurgical alternatives which perform the role of short-circuiting better than mild steel...
As to re-annealing: Wouldn't raising the temperature above the Curie point be adequate? Or is that merely synonymous in magnetic parlance with "re-annealing"?
Yes, yes it was.
I love the two-handed pointer, with dedicated modifier keys (which resemble piano keys in their size and pivoting movement) under the left hand, and the pointer itself under the right.
It might be said that this layout was copied, much later, as the common control mechanism for PC-based first-person games (ASFW keys under left hand, mouse in right).
[citation needed]
Naaah.
The TV whines at about 15kHz. It's not out-of-spec, but just a loose winding on the flyback transformer. No big deal.
I can't hear it much anymore except in extreme cases, but when I was a kid it'd drive me nuts. I could walk by houses on a quiet night and tell without looking if they had a TV on, or if they had more than one on (as long as they were tuned to different channels -- the slight difference in frequency would cause the sound to heterodyne).
The dishwasher is just an appliance, not a structural item. How many screws hold the washing machine, clothes drier, fridge, or tank water heater in place?
The two screws are just there to keep the thing from tipping forward annoyingly when the racks are all the way out. They're perfectly adequate for this role (actually, one screw in the right spot would be adequate -- three points define a plane...).
I've seen children swing from cabinet doors, teenagers slam them with wild abandon, and homeowners who don't know how to tighten a screw when things get wonky with time. I've seen top dollar decks rot from general lack of maintenance. And I've seen folks who are unqualified to hang anything on any wall, because the first thing they do is reach for a hammer and a nail, and when that doesn't work, they find a bigger hammer.
My house has some drywall that is 50 or 60 years old, just 3/8" thick, and brittle. It holds stuff just fine, provided that appropriate fasteners are used in appropriate ways. It's not rocket surgery.
Some people try to take care of their things. Some people don't think they have time to figure out how. The former group is proud of their collection of tools and earned experience. The latter bemoans every failure as being someone else's problem without ever considering if there were something they could have done differently.
*shrug*
A Faraday cage does little or nothing when faced with a static magnetic field.
At RF frequencies, it does work fine. But there's a world of difference between (essentially) DC and a few hundred KHz. Think of it as series inductance creating a low-pass filter.
Come to think of it, I'd not be surprised in the slightest if a Faraday cage performed exactly like an inductor, complete with a first-order slope...
(Please note that I'm considering the claim that they've experienced a hard drive failure to be a coincidence.)
Flat sheet steel does little to curb static magnetic fields.
Experiment: Find a CRT, and a magnet. Observe how they behave together. Next, put something steel (the side from a PC case?) between the two, and observer that they behave almost the same... Feel free to repeat with iron filings, aluminum and steel cans, old license plates, or whatever. It shields somewhat, and does a bit of scattering, but it's lousy (and certainly not "very good").
One can use an appropriately curved chunk of curved steel to accomplish some shielding. See, for instance, shielded speakers, which use a cup to completely surround the magnet, sometimes in addition to a second magnet which is only used to help counteract the external field of the first.
But, you know, your PC case isn't shaped like that.
There are certain high-permeability materials (Mu-metal being one) which do far better, but they're pretty far removed from the common mild steel of a PC. (I haven't verified this, but I've read that Mu-metal is used on the back side of the neodymium magnets inside of a hard drive, and if that is the case it would easily explain how one side sticks ferociously to the side of the fridge, and the other side won't even pick up a paper clip.)
CRTs (whether televisions, computer monitors, or vector displays) are easily influenced by magnetic fields, both static and otherwise. They operate using magnets, and it doesn't take much to disturb appreciably disturb them.
That said: Bad wiring, in and of itself, doesn't make for radio interference. The singular exception to this is when there is arcing. But if that were the case the place would've likely already burned, or the fault would otherwise have destroyed/fixed itself, or at least things would smell funny on a regular basis...and you'd literally see arcing on analog TV broadcasts, in the form regularly-occurring horizontally-aligned lines of static.
So, it's probably not arcing. But bad electronics and other noisy loads can cause all kinds of interference, however.
The usual culprits are lamp dimmers and fluorescent ballasts, ugly switching supplies, and motors with bad brushes. Any noise generated by stuff like this will radiate throughout (and around) the house.
And. It may not even be a problem inside the house: It might be the neighbor down the way, or a near(ish) farm or factory sharing the same leg. I mean: Your folks don't exactly have their own generating station, so whatever comes down the wire from outside is also going to radiate inside.
If you're really curious about it, turn things off at their place one by one (either by unplugging them, or perhaps at the breaker panel in the case of dimmer-equipped lighting circuits and fixed equipment like the furnace and the dishwasher) until you narrow the problem down to a specific device which verifiably causes it, and then repair or replace that item.
And if it's still noisy with literally everything off, the problem is not within the house. (There's ways to overcome that, as well, if it's important. My guess is that it's not important.)
Useless anecdote: I was sure I had a wiring fault, grounding issue, bad plugs/wires/coil/distributor, or something else wrong in my work truck, since AM reception was totally hosed no matter where I was driving...though FM worked quite well. I ignored it for a long while since I didn't listen to AM much anyway. One day, on a whim, I pulled the cell phone charger out of the dashboard socket and -instantly- the AM reception went from "meh" to relatively awesome. And that's just a little DC-DC converter. (The charger subsequently died in a fire, just to ensure nobody else would ever find it and try to use it.)
And more useless information: Analog (NTSC) broadcast television uses AM for video, and FM for audio.
CRTs are affected by even the magnetism of the Earth, and will change ("distort") depending on their relative orientation. Better CRT displays, from back in the day at least, have a control (commonly labeled "rotation") to help offset this exact problem.
Remember, CRTs work with magnetic fields: One might even say that all a CRT does is visualize magnetism. If any outside force changes those fields, the resultant picture will change accordingly and measurably.
That said: I've had static magnetic fields of unknown origin mess with TVs before. I suspect it was an iron counterweight for a window sash causing the issue, but was never sure, since I simply moved the TV and the problem went away.
I don't think I'd ever be lawyering up to go head-to-head with a builder over such an issue unless the kitchen knives had a hard time staying in the drawer, and the fillings were getting sucked out of my teeth.
And even then, as others have pointed out, it's easy to degauss steel: Wrap a welding lead around it, and turn the welder on. Bonus points for gradually reducing amperage to maximize results.
At worst, this entails the builder borrow an arc welding kit from somewhere, and pay someone to patch and paint some drywall. No big deal, and certainly a lot cheaper than a few hours with a lawyer. If it's not part of the contract, and it's a really big deal for some reason, then being reasonable ("OK, Mr. Builder, you degauss this beam and fix the drywall, I'll paint it and clean up") would have probably gone a long way...
I think we should start at 100,000.
I frequently give positive moderation to unpopular opinions that even I don't agree with, if the logic behind them is sane and the human reasoning seems genuine. Especially if the comment also brings new facts to a discussion.
I cannot imagine that I am the only person with mod points to adopt this behavior.
What caused you to take Top Gear seriously in the first place?
It's just entertainment, and I love their antics. But they're just...antics.
I'm not sure how much of a big deal that really is, unless it's easy to jump timing when changing a water pump out.
IIRC, timing belts these days are reinforced with Kevlar. They should not stretch appreciably, but they will wear out eventually. Replace it at the specified interval (40k or 60k depending on the Kia), tighten things properly at that time, and call it done until the next replacement interval.
It's not abrupt.
The saw spins up in about a quarter-second second, and dims the lights for a moment. It takes about two seconds to stop, and does not dim the lights at that time.
This is far more indicative of resistive braking than of reversing the motor.
It's also simpler, cheaper, and has fewer parts to wear out. And since the saw was very cheap, I'm inclined to believe that its brake is also very cheap.
And I can run that specific OS on commodity hardware. I don't have to use a computer that is built by Microsoft.
I like choices when buying hardware. While I believe that Apple produce very fine hardware indeed, I very much enjoy the freedom to choose other manufacturers. Today's box for developing a "serious app" is going to be tomorrow's box for tinkering with hardware, and I like tinkering with hardware and stretching my dollars as far as I can.
I've always tried to put my money into the underdog CPUs whenever possible, whether that be Cyrix/IBM (6x86MX), or even IDT, as long as they worked with common industry standard parts. There was a period in the early-mid 90's where DEC's Alpha had potential to be real and hackable alternative. It is very unfortunate that we currently only have two realistic choices.
I care because I don't have a Mac. I do have a bunch of PCs which I can do almost anything else with, though...
There is a plain and definite difference between "needing a computer" and "needing a computer from a specific manufacturer." If you can't detect that difference, then there's really no hope for you.
Yes, kind of.
"Regenerative braking" is just another way to brake (ie: slow down) a moving vehicle, with the benefit of storing some of that energy as electricity. Other common methods using discs or drums lose dissipate all of the energy as heat.
A similar braking system is used on the small(ish) AC-powered compound miter saw that I have, which rapidly stops the blade after releasing the trigger. But instead of using the stored energy of the forward-moving vehicle to charge a battery, it gets dumped through a resistor and converted to heat. It's simple, easy, and cheap: Compared to a saw which does not brake after use, it just requires a slightly fancier switch, a little more wire, and a resistor, since a common AC motor is just a generator running backward (and vice-versa).
Just because it's not mechanically-operated and does not rely on friction to get it done does not mean that it is not a brake.
The Tesla also has disc brakes, and I'm sure it can stop very quickly indeed if directed to do so, which is important on a car. My saw does not have a mechanical brake since it's just a convenience item, and it's OK if it takes a few seconds for it to stop spinning.
No.
If you develop for Windows, you can buy any of a wide array of computers to do the work, from a large number of different manufacturers -- including Apple. You can even build one yourself using common parts that meet industry-standard specifications like ATX.
If you want to develop for an iPhone, you have to have a Mac. Not a Dell, not something you hobbled together with interchangable bits, but an actual Mac.
XCode for IPhone development is free ...as long as you already have a Mac running a sufficiently-recent release of OS X.
Otherwise, not free.
Aren't bankers and lawyers essentially the same thing?
Smoke and mirrors, at this point.
Not if the P2P back-end existed only in vehicular or fixed installations, instead of on one's hip.