An incandescent bulb will usually burn out SOONER when run on DC, compared to AC.
The phenomenon at work here is "filament notching". Tungsten atoms evaporate from the negative end of the filament, and migrate through the vacuum to the positive end. Once enouch material is removed, the increased current density causes a "hot spot" near the negative end, and the filament fails open.
With AC operation, the evaporated tungsten redeposits as quickly as it evaporates.
And once you have packed the walls with improper wiring, are you going to completely remove it when you go to sell the house? Even if that requires ripping out walls, etc.?
Otherwise, you are forcing an unseen hazard on the next buyer. A hazard that they DIDN'T have the "freedom" to knowingly assume for themselves.
Issues like this are why we HAVE little things like electrical and fire codes...
The N2O disassociates into nitrogen and oxygen at combustion chamber temperatures, and the oxygen allows additional fuel to be burned, producing the horsepower increase. The nitrogen content acts as a "detonation buffer", preventing preignition of the mixture from the increased chamber pressures/temperature.
The other thing that nitrous does is to act as a "chemical intercooler" when injected into the intake manifold. When the liquified gas flashes into a vapor, it absorbs large amounts of heat, cooling the intake charge and increasing it's density.
In order to be compliant with various building codes (such as the National Electrical Code), all materials used must be "listed as suitable for the application" by UL or another "Nationally Recognized Testing Lab" (NRTL).
When these building codes are adopted into law, this creates a "captive market" for the NRTLs through government coercion. Not quite "Capital-"L" Libertarian philosophy, now is it?
Not to mention the organizations that publish the (copyrighted!) building codes in the first place!
IMHO, once a code is adopted into public law, it should become public domain! But people can and have been sued for making things like bulding codes freely available online.
to build a computer that will be in a landfill in 10 years because it is completely obsolete.:(
If they restored the original Predicta as a TV set and sold it to a collector, they could have purchased one of the modern repro cabinets to hack up for a computer case.
Ever notice that those 2 verses are hardly ever taught to kids when they learn that song in public schools?
It simply wouldn't DO to have kids questioning the class structure or the concept of "property rights", now would it? Hell, next thing you know, the kids might listen to some of Guthrie's OTHER songs, like "Pretty Boy Floyd", with commie/pinko lyrics like this:
"There's a many a starving farmer The same old story told How this outlaw paid their mortgage And saved their little home. Others tell you 'bout a stranger That come to beg a meal And underneath his napkin Left a thousand dollar bill.
It was in Oklahoma City It was on a Christmas Day There come a whole car load of groceries With a letter that did say: You say that I'm an outlaw You say that I'm a thief Here's a Christmas dinner For the families on relief.
Now as through this world I ramble I see lots of funny men Some will rob you with a sixgun And some with a fountain pen. But as through your life you travel As through your life you roam You won't never see an outlaw Drive a family from their home"
Woody must be spinning in his grave over this lawsuit. Looks like the bastards with the fountain pens won...:(
When I used to repair VCRs, both Sony and Panasonic had "consumer" and "commercial/industrial" units where the only difference was the model number, the color of the cabinet, and the video connectors (consumers got RCA jacks, the industrials got the much more robust BNCs).
When you include costs like veteran's benefits and the interest on the national debt (about 80% of which was caused by past military spending),the "defense" budget accounts for nearly 50% of the US federal budget each year!
But the ones who entered science fairs tended to be, I guess.
FWIW, I went to a Vo-Tech HS, and studied electronics technology. Myself and another student made a project out of a child's toy robotic arm (IIRC it was called an "armitron") that we rigged up with a half-dozen DC motors and controlled via the parallel port on a ZX81. Programmed in BASIC to execute simple moves. This would have been during the junior year of HS.
Is that all there is to it? A mouse moving the stylus of an etch-a-sketch? Now if it incorporated a "drag and drop" or "selective erase" feature, it might be interesting. As it is, this would make a neat high school science fair project, but a final project for an EE degree?
Why was a microcontroller even NEEDED here? Rewiring the mouse to provide the raw X and Y encoder wheel pulses, and applying them right to the stepper drivers would give substantially the same results without the MCU and all the programming. If the stepper drivers need step and direction signals rather than quadrature pulse trains, run the encoder signals through one of the LSI/CSI encoder interface chips to get whatever you want without writing code or burning it onto a chip. A programmable solution for something this simple seems like complexity for complexity's sake...
You might want to narrow your sweeping indictment there.
I run a pair of homebrew tube monoblocks (4X 6550 per channel), and you won't find any "gold plated super mojo cables" in my system anywhere. The patch cords are mostly homemade from RG-58 coaxial cable, and the speaker cables are 14 gauge zip cord from Home Depot.:)
At least the homebrew/techie users of tubes are generally knowledgable enough to avoid the audiophool snakeoil out there. Many of us make a living in electronics design, afterall.
The Tube vs. Transistor sound debate is subject to too many variables (source material, speakers, room acoustics, individual hearing variations, etc.) to make a solid pronouncement on one side or the other. There are great solid state amps and shitty tube amps out there.
To me, the primary advantage of tubes is aesthetic (can't beat the warm glow in a dark room!), and the utter simplicity of the circuit designs. After working with semiconductors all week at work, it makes a nice change to work with "retro" technology as a hobby. A polished metal chassis full of heavy iron and glass bottles has a "soul" that the black/silver plastic riceboxes from Best Buy never will.
Back during the first Gulf War, the US military was having constant reliability problems with modern solid state HF receivers. The solid state front ends were getting blown out by static charges developed by sandstorms blowing past the antennas in low humidity.
They solved the problem by pulling old tube receivers out of mothballs. The rigs they used, the early-'50s designed R-390A/URR, are still recognized as probably the best HF receiver ever built, tube or SS. Renowned for freedom from overload in strong signal conditions, with a noise floor close to the galactic limit. They even had a "digital" frequency readout, with a mechanical odometer-type display. These rigs have a cultlike following these days, with many websites dedicated to them, including:
To be fair, 2 megawatts worth of transistors would probably weigh somewhat less that a pair of these tubes. The solid state weight savings would be in the output transformer and filament transformer, which the tubes would need, but a solid state amp wouldn't.
The other weight comparisons would probably be a wash. Transistors would need massive heatsinks and blowers, while the tubes would need a water cooling system. And both would need a 2+ megawatt power supply.
Tubes have advantages at high power levels, but weight reduction isn't among them! There is a REASON that they call old tube radio equipment "boatanchors", ya know!:)
The primary advantage would be reduced circuit complexity and component count. Only 2 active devices versus hundreds/thousands.
Solid state has pretty much taken over AM broadcasting at the 50 kW level, but AFAIK, the higher powered shortwave rigs as you describe are still running tubes. CERTAINLY rigs at the megawatt level are.
FM broadcasting is still dominated by tubes, but solid state is starting to make inroads at lower power levels.
"Indeed, thats why tube amps need a coupling transformer between the tubes and the speaker."
And why vacuum tube RF transmitters use a matching network (Typically a Pi-network) between the final amplifier tube and the antenna.
The concept of impedance matching is the same, only the components used are different. BTW, solid state RF power amplifiers use ferrite broadband transformers for the same reason.
"You have a source for tubes than can handle (assuming we are hooking up some magically-able-to-handle-3kw-home-speaker) 20 amps of current? If so, show me the money. Otherwise, you know the old saying, shut up or put up."
Ok, how about:
http://www.cpii.com/eimac/catalog/169218.htm
This little baby will handle a plate current of 125A at 22.5 kV! In class B audio service, a pair will get you a bit over 2 MEGAWATTS of output.
when the FCC capped AM broadcasting at 50 kW maximum. And their current (50 kW) transmitter is fully solid state. Lotsa info at http://hawkins.pair.com/wlw.shtml
The ITU (International Telecommunications Union) regulates the HF spectrum on an INTERNATIONAL basis, because HF signals to not respect national borders. If BPL causes international interference problems, the ITU may well regulate it out of existence.
http://www.itu.int/home/
Researchers at the Moore School of Electrical Engineering, U. of Penn. (Home of the original ENIAC) made a functional equivalent on a custom silicon chip to commemorate the 50th anniversary a few years back. Info at:http://www.ee.upenn.edu/~jan/eniacproj.html
You would STILL need heavy busbars with 12VAC, for the same reason you would need them with low voltage DC--VOLTAGE DROP. To transfer a given amount of power at low voltage, the current must be correspondingly higher. High currents cause excessive voltage drops at connections and in conductors. Wire sizes become impractical, both from a physical as well as a cost standpoint (copper costs money!).
The 120 VAC standard is a good compromise between required current and voltage hazard.
But many government bodies then go on to make compliance with UL or ANSI standards mandatory.
Ever seen the price of geting a copy of a UL or ANSI standard? How about national building codes drawn up by "Non-Profit" organizations like the NFPA?
If such privately-written standards are enacted into public law, they should be freely available to the public, no?
Slashdot Mirror
An incandescent bulb will usually burn out SOONER when run on DC, compared to AC.
The phenomenon at work here is "filament notching". Tungsten atoms evaporate from the negative end of the filament, and migrate through the vacuum to the positive end. Once enouch material is removed, the increased current density causes a "hot spot" near the negative end, and the filament fails open.
With AC operation, the evaporated tungsten redeposits as quickly as it evaporates.
And once you have packed the walls with improper wiring, are you going to completely remove it when you go to sell the house? Even if that requires ripping out walls, etc.? Otherwise, you are forcing an unseen hazard on the next buyer. A hazard that they DIDN'T have the "freedom" to knowingly assume for themselves. Issues like this are why we HAVE little things like electrical and fire codes...
[quote]Although many many disagree, the US government doesn't actually control the news media.[/quote]
Correct. Here in the land of the "free market", private corporations control both the news media AND the government. Much more efficient, you see...
The N2O disassociates into nitrogen and oxygen at combustion chamber temperatures, and the oxygen allows additional fuel to be burned, producing the horsepower increase. The nitrogen content acts as a "detonation buffer", preventing preignition of the mixture from the increased chamber pressures/temperature.
The other thing that nitrous does is to act as a "chemical intercooler" when injected into the intake manifold. When the liquified gas flashes into a vapor, it absorbs large amounts of heat, cooling the intake charge and increasing it's density.
In order to be compliant with various building codes (such as the National Electrical Code), all materials used must be "listed as suitable for the application" by UL or another "Nationally Recognized Testing Lab" (NRTL).
When these building codes are adopted into law, this creates a "captive market" for the NRTLs through government coercion. Not quite "Capital-"L" Libertarian philosophy, now is it?
Not to mention the organizations that publish the (copyrighted!) building codes in the first place!
IMHO, once a code is adopted into public law, it should become public domain! But people can and have been sued for making things like bulding codes freely available online.
to build a computer that will be in a landfill in 10 years because it is completely obsolete. :(
If they restored the original Predicta as a TV set and sold it to a collector, they could have purchased one of the modern repro cabinets to hack up for a computer case.
Ever notice that those 2 verses are hardly ever taught to kids when they learn that song in public schools?
It simply wouldn't DO to have kids questioning the class structure or the concept of "property rights", now would it? Hell, next thing you know, the kids might listen to some of Guthrie's OTHER songs, like "Pretty Boy Floyd", with commie/pinko lyrics like this:
"There's a many a starving farmer
The same old story told
How this outlaw paid their mortgage
And saved their little home.
Others tell you 'bout a stranger
That come to beg a meal
And underneath his napkin
Left a thousand dollar bill.
It was in Oklahoma City
It was on a Christmas Day
There come a whole car load of groceries
With a letter that did say:
You say that I'm an outlaw
You say that I'm a thief
Here's a Christmas dinner
For the families on relief.
Now as through this world I ramble
I see lots of funny men
Some will rob you with a sixgun
And some with a fountain pen.
But as through your life you travel
As through your life you roam
You won't never see an outlaw
Drive a family from their home"
Woody must be spinning in his grave over this lawsuit. Looks like the bastards with the fountain pens won...:(
When I used to repair VCRs, both Sony and Panasonic had "consumer" and "commercial/industrial" units where the only difference was the model number, the color of the cabinet, and the video connectors (consumers got RCA jacks, the industrials got the much more robust BNCs).
When you include costs like veteran's benefits and the interest on the national debt (about 80% of which was caused by past military spending),the "defense" budget accounts for nearly 50% of the US federal budget each year!
http://www.warresisters.org/piechart.htm
But the ones who entered science fairs tended to be, I guess.
FWIW, I went to a Vo-Tech HS, and studied electronics technology. Myself and another student made a project out of a child's toy robotic arm (IIRC it was called an "armitron") that we rigged up with a half-dozen DC motors and controlled via the parallel port on a ZX81. Programmed in BASIC to execute simple moves. This would have been during the junior year of HS.
Is that all there is to it? A mouse moving the stylus of an etch-a-sketch? Now if it incorporated a "drag and drop" or "selective erase" feature, it might be interesting. As it is, this would make a neat high school science fair project, but a final project for an EE degree?
Why was a microcontroller even NEEDED here? Rewiring the mouse to provide the raw X and Y encoder wheel pulses, and applying them right to the stepper drivers would give substantially the same results without the MCU and all the programming. If the stepper drivers need step and direction signals rather than quadrature pulse trains, run the encoder signals through one of the LSI/CSI encoder interface chips to get whatever you want without writing code or burning it onto a chip. A programmable solution for something this simple seems like complexity for complexity's sake...
You might want to narrow your sweeping indictment there. I run a pair of homebrew tube monoblocks (4X 6550 per channel), and you won't find any "gold plated super mojo cables" in my system anywhere. The patch cords are mostly homemade from RG-58 coaxial cable, and the speaker cables are 14 gauge zip cord from Home Depot. :)
At least the homebrew/techie users of tubes are generally knowledgable enough to avoid the audiophool snakeoil out there. Many of us make a living in electronics design, afterall.
The Tube vs. Transistor sound debate is subject to too many variables (source material, speakers, room acoustics, individual hearing variations, etc.) to make a solid pronouncement on one side or the other. There are great solid state amps and shitty tube amps out there.
To me, the primary advantage of tubes is aesthetic (can't beat the warm glow in a dark room!), and the utter simplicity of the circuit designs. After working with semiconductors all week at work, it makes a nice change to work with "retro" technology as a hobby. A polished metal chassis full of heavy iron and glass bottles has a "soul" that the black/silver plastic riceboxes from Best Buy never will.
Back during the first Gulf War, the US military was having constant reliability problems with modern solid state HF receivers. The solid state front ends were getting blown out by static charges developed by sandstorms blowing past the antennas in low humidity.
They solved the problem by pulling old tube receivers out of mothballs. The rigs they used, the early-'50s designed R-390A/URR, are still recognized as probably the best HF receiver ever built, tube or SS. Renowned for freedom from overload in strong signal conditions, with a noise floor close to the galactic limit. They even had a "digital" frequency readout, with a mechanical odometer-type display. These rigs have a cultlike following these days, with many websites dedicated to them, including:
http://www.r390a.com/
and
http://www.r390a.net/
To be fair, 2 megawatts worth of transistors would probably weigh somewhat less that a pair of these tubes. The solid state weight savings would be in the output transformer and filament transformer, which the tubes would need, but a solid state amp wouldn't.
:)
The other weight comparisons would probably be a wash. Transistors would need massive heatsinks and blowers, while the tubes would need a water cooling system. And both would need a 2+ megawatt power supply.
Tubes have advantages at high power levels, but weight reduction isn't among them! There is a REASON that they call old tube radio equipment "boatanchors", ya know!
The primary advantage would be reduced circuit complexity and component count. Only 2 active devices versus hundreds/thousands.
Solid state has pretty much taken over AM broadcasting at the 50 kW level, but AFAIK, the higher powered shortwave rigs as you describe are still running tubes. CERTAINLY rigs at the megawatt level are.
FM broadcasting is still dominated by tubes, but solid state is starting to make inroads at lower power levels.
"Indeed, thats why tube amps need a coupling transformer between the tubes and the speaker." And why vacuum tube RF transmitters use a matching network (Typically a Pi-network) between the final amplifier tube and the antenna. The concept of impedance matching is the same, only the components used are different. BTW, solid state RF power amplifiers use ferrite broadband transformers for the same reason.
"You have a source for tubes than can handle (assuming we are hooking up some magically-able-to-handle-3kw-home-speaker) 20 amps of current? If so, show me the money. Otherwise, you know the old saying, shut up or put up."
Ok, how about:
http://www.cpii.com/eimac/catalog/169218.htm
This little baby will handle a plate current of 125A at 22.5 kV! In class B audio service, a pair will get you a bit over 2 MEGAWATTS of output.
when the FCC capped AM broadcasting at 50 kW maximum. And their current (50 kW) transmitter is fully solid state. Lotsa info at http://hawkins.pair.com/wlw.shtml
The ITU (International Telecommunications Union) regulates the HF spectrum on an INTERNATIONAL basis, because HF signals to not respect national borders. If BPL causes international interference problems, the ITU may well regulate it out of existence. http://www.itu.int/home/
Researchers at the Moore School of Electrical Engineering, U. of Penn. (Home of the original ENIAC) made a functional equivalent on a custom silicon chip to commemorate the 50th anniversary a few years back. Info at:http://www.ee.upenn.edu/~jan/eniacproj.html
Open filament? Excessive gas? Cathode interface? Low Emission? Loss of vacuum?
And to add to the fun, some cars have bolts with SAE size hex heads and metric threads, or vice versa.
You would STILL need heavy busbars with 12VAC, for the same reason you would need them with low voltage DC--VOLTAGE DROP. To transfer a given amount of power at low voltage, the current must be correspondingly higher. High currents cause excessive voltage drops at connections and in conductors. Wire sizes become impractical, both from a physical as well as a cost standpoint (copper costs money!). The 120 VAC standard is a good compromise between required current and voltage hazard.
The i960 also shows up in some industrial control equipment like PLCs and motor controllers.
But many government bodies then go on to make compliance with UL or ANSI standards mandatory. Ever seen the price of geting a copy of a UL or ANSI standard? How about national building codes drawn up by "Non-Profit" organizations like the NFPA? If such privately-written standards are enacted into public law, they should be freely available to the public, no?