A couple years ago I called Airtouch to request exactly that - something was sending an (apparently) automated numeric page to one of the new pagers we got.
Airtouch's policy was that they couldn't stop it and they required a court order to tell me where they were coming from.
NiCds are a poor choice of battery [...] they get REAL hot when charging
If you let them overcharge (which is how nicads get trashed anyway). The actual charging is endothermic (the battery cools slightly). NiMH is exothermic but somehow the car companies have dealt with that too (NiMH also has even lower charging efficiency - 66%)
The low energy density is a problem, but for this application nicads' ability to charge/discharge quickly (faster than any other battery type) makes up for it. You don't need to run more than a half-hour or so on your battery pack.
There are already quite a number of nicad recycling points across the US. On a large scale for the customer, I don't think this would be any different than taking your old lead-acid car battery or used motor oil back to the car parts shop when you change it.
You're taking the mechanical power from the engine, converting it to electricity, losing some energy to heat, storing it in batteries (losing some energy to heat), converting it from DC to AC (losing some energy to heat), then running the motor (losing some energy to heat)
You don't actually need to invert the battery power - DC motors are plentiful. People used to make larger DC/DC convertors or AC frequency convertors by coupling two motors together (a motor-generator set) - a couple of google searches suggest efficiencies of 73% for 100hp systems can be reached - maybe sacrifice a couple percentage points for something reasonably lightweight, as that link discussed things that remain bolted down.
More google searches suggest the coulometric efficiencies of nicads at rapid charge rates (up to about 15 minutes per charge) is 83%. 83%*70%=58% efficiency (42% losses) for this setup.
I guess my question was, is this inefficiency greater than the inefficiency caused by carrying around a heavier battery and drivetrain and running the engine at suboptimal speeds? The car companies probably did this math a long time ago and came to your conclusion.
Economically, there's NO WAY a company can produce a hybrid for the same price as a comparable gas only car. It has more parts!
That depends on how you do it. The Prius and Insight use their engines to drive the wheels, and the motors to assist that, but it doesn't have to be done that way.
If you have the engine turn a generator charging batteries, with drive motors for each wheel, you can leave out the clutch, transmission, starter, drivetrain, and differential. The engine can run at a constant speed (and thus be designed to be quiet at that speed), the batteries can be relatively small/lightweight (limited by how often you want to cycle them), and the car will have a decent amount of low-speed torque as well.
Would anyone like to comment on why the Prius and Insight were not designed this way?
What if this doesn't work, even after a year? What if you swear at your director constantly during your quarterly review telling him exactly what you think of him and nothing happens? (Come to think of it, I actually got rated above average on that review - sick.)
I finally quit (hitting that magic 100%-turnover-in-three-months number for our department), was unemployed for 10 weeks, and now make more and am much happier. Of course, I had great references from my previous managers who got tired of the place before I did, and I had enough saved up to take the risk.
Go to Maxim IC's web site, and order an evaluation kit with a couple MAX787's to deliver the 5v rail (they handle 5 amps each) and a MAX765 to handle the -12V rail. Most motherboards don't actually need -5V but if yours does the MAX764 will do nicely.
The finished circuit doesn't even get that warm with the IC's bolted to the aluminum case, even when it's delivering 80 watts.
I've tried, but Maxim IC simply will not take your money for small orders, even after you explain to them that you will never ever need 3000 of the things. You have to have them ship you the stuff as an eval kit for free.:)
Let's say that tomorrow I wrote the best book that I had ever written, and it continues to be the best book that has ever been written by me.
Let's also say that in 20 years it is still selling modestly. But all of a sudden, wham, I no longer see a penny from it, despite the fact that at least _some_ people are still buying it.
So write another book. Article I section 8 of the Constitution says "limited times" - the fact that you believe you're entitled to royalties from such a book for your entire life shows just how perverted this law has become.
By writing another book, you're doing your part to "promote the progress of science and useful arts" just as the authors of the constitution intended.
Re:How is he powering this setup?
on
Cringely's Bank Shot
·
· Score: 5, Informative
I'm curious as to how he's powering this setup.
It's passive. No power needed. Basically, a wave received from one antenna will travel down a transmission line to an antenna connected at the other end and radiate out (and vice versa) with very little loss.
see, you technically Opt-In for your phone number and address to be listed in the phone book
At least in Washington state both Qwest and Verizon will automatically put you in the phone book when you buy a phone line. You have to pay a monthly fee to get an unlisted number.
No, the wavelength of an 800mhz anything is 299792458 meters per second (speed of light) divided by 800000000 cycles per second or.375 meters. Which.5" mesh will block with no problem.
Oh, and "800mhz" cell phones typically use the AMPS analog cell bands at 824.04MHz-893.7MHz, so it's more like 33.5-36.3cm.
If one were really serious (ly-screwed-up IMHO) about this, one could construct their home as a Faraday cage. Just lay chicken wire around the entire frame (through the double-paned windows and attached to the steel doors' frame, and use conductive weatherproofing in the door jambs) and connect it all together (solder/weld/twist all points of all corners together) into one giant grounded box. All RF with wavelengths less than about one-tenth the gap of the chicken wire will be blocked (the same principle is used for the window on your microwave oven, it's also why you can see through some satellite dishes). If you want this home to have power, you'll want to hook the breaker panel to a large iron-core transformer which will act as a low-pass filter. A similar low-pass filter can be used for the phone line.
Such a home would be unable to recieve TV or radio, DSL or power-line networking would never pass through, cellphones and government-planted transmitter bugs would be dead inside, and you wouldn't have to worry much about lightning strikes either. Of course it would be cheaper to move out into the boonies.
Not to me. I've seen the same 30-40% increase copying data between two disks on the same IDE chain as opposed to the exact same two disks on different IDE chains ever since UDMA support came out.
But it is broken, well, it is if you have a UPS. Why do AC to DC to AC to DC, when you could have a standard connector for battery backup on the power supply?
Chances are, your computer's power supply already does AC->DC->AC->DC, even without the UPS. 60hz magnetics are very large/heavy so almost all modern power supplies first rectify to 120V DC, then invert to an intermediate voltage at 20khz or so.
Anyway, would you want your UPS to need 12V, 5V, 3.3V, -5V and -12V battery sets? Would you want to have to modify it everytime Intel decides power supplies need a new connector?
it seems to be a rather interesting privacy/security problem that MS Exchange would include the username in the HTTP request referrer field.
The article prompted me to check this - it appears Outlook 2000 + IE5.01 at least does not send any Referer data when opening a URL sent as normal text in an email (which Outlook presents as a link). I'm very curious why ZDNet said that...
Can someone effectively execute a DOS attack by uplinking to the satellite with a powerful signal (the frequency would be easy to 'snoop' from our transmitting antenna), thus preventing us from commanding it?
Absolutely. Amateur radio operators have worked earth-moon-earth on 144 and 440mhz for decades - there's no reason someone couldn't build the equipment to do it on your frequency. However, the antennas and such are rather obvious-looking. Any nation's communications commission would be able to spot one of those very easily in case it needs to be hunted down, and it does raise the bar beyond what most crackers are motivated to do.
In general, how do receivers handle multiple command carriers (would there be too much noise to command)?
The mathematical formula for this is Shannon's Law. Run your numbers through it (and keep in mind some modulations have significant inefficiences of their own). I can't imagine missing a couple communications windows with your satellite would be the end of the world, though.
...tell me if you think it is secure, or whether you'd want to crack it.
For something with the replacement cost of a satellite, you want guarantees, not estimates of society's intentions. If you want your control center to be the only station capable of transmitting commands to the satellite, your satellite needs a way to make sure it's the control center that's doing the sending. If you want to make sure your telemetry data is from that satellite, you need to make sure it's the satellite that's doing the sending. Note that encryption isn't really needed here (a cracker knowing what you're doing with the satellite doesn't help much, as this is not a spy satellite) but some form of public key signing should be employed. It also guarantees that your control messages won't arrive corrupted (although I'd imagine you'd already have something to protect against that).
At 2400mhz, 3-4db is equivalent to the loss in 45-60 feet of LMR-400 coax (or 12-16 ft of RG-58), according to this calculator.
For those that would like to put an 802.11b antenna on their roof without worrying about weatherproofing their access point, this may be just the thing.
Re:I must be missing something
on
Review: SliMP3
·
· Score: 2
The hum you're hearing is from the 60hz AC power. You have a ground loop (multiple paths to ground). There's several ways out of this:
Run your amp and computer off the same power strip
Don't ground your computer (not really recommended)
Pick up a ground-loop isolator at an electronics store
Get a pair of baluns (balanced<->unbalanced) and use them for your line out
Get a different computer (can be diskless/fanless if you're concerned about noise) and plug it into the same power strip as your amp. Ssh into it and and play your music from there. This is what I did since I had all the parts lying around and I didn't want to put my amp on a UPS.
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Gigabit ethernet is actually a 250mhz signal.
Bits/second != Hertz
If American Airlines wins this case, what happens to froogle.google.com?
The lunar day is 24 hours, 50 minutes.
That quote may not have been written by Emerson.
Airtouch's policy was that they couldn't stop it and they required a court order to tell me where they were coming from.
We ended up changing the pager's number.
If you let them overcharge (which is how nicads get trashed anyway). The actual charging is endothermic (the battery cools slightly). NiMH is exothermic but somehow the car companies have dealt with that too (NiMH also has even lower charging efficiency - 66%)
The low energy density is a problem, but for this application nicads' ability to charge/discharge quickly (faster than any other battery type) makes up for it. You don't need to run more than a half-hour or so on your battery pack.
There are already quite a number of nicad recycling points across the US. On a large scale for the customer, I don't think this would be any different than taking your old lead-acid car battery or used motor oil back to the car parts shop when you change it.
You don't actually need to invert the battery power - DC motors are plentiful. People used to make larger DC/DC convertors or AC frequency convertors by coupling two motors together (a motor-generator set) - a couple of google searches suggest efficiencies of 73% for 100hp systems can be reached - maybe sacrifice a couple percentage points for something reasonably lightweight, as that link discussed things that remain bolted down.
More google searches suggest the coulometric efficiencies of nicads at rapid charge rates (up to about 15 minutes per charge) is 83%. 83%*70%=58% efficiency (42% losses) for this setup.
I guess my question was, is this inefficiency greater than the inefficiency caused by carrying around a heavier battery and drivetrain and running the engine at suboptimal speeds? The car companies probably did this math a long time ago and came to your conclusion.
Thanks for the response.
That depends on how you do it. The Prius and Insight use their engines to drive the wheels, and the motors to assist that, but it doesn't have to be done that way.
If you have the engine turn a generator charging batteries, with drive motors for each wheel, you can leave out the clutch, transmission, starter, drivetrain, and differential. The engine can run at a constant speed (and thus be designed to be quiet at that speed), the batteries can be relatively small/lightweight (limited by how often you want to cycle them), and the car will have a decent amount of low-speed torque as well.
Would anyone like to comment on why the Prius and Insight were not designed this way?
Are you posting anonymously because you don't want everyone to know you listen to the same music as your parents?
I don't think it'll be an issue.
What if this doesn't work, even after a year? What if you swear at your director constantly during your quarterly review telling him exactly what you think of him and nothing happens? (Come to think of it, I actually got rated above average on that review - sick.)
I finally quit (hitting that magic 100%-turnover-in-three-months number for our department), was unemployed for 10 weeks, and now make more and am much happier. Of course, I had great references from my previous managers who got tired of the place before I did, and I had enough saved up to take the risk.
Go to Maxim IC's web site, and order an evaluation kit with a couple MAX787's to deliver the 5v rail (they handle 5 amps each) and a MAX765 to handle the -12V rail. Most motherboards don't actually need -5V but if yours does the MAX764 will do nicely.
The finished circuit doesn't even get that warm with the IC's bolted to the aluminum case, even when it's delivering 80 watts.
I've tried, but Maxim IC simply will not take your money for small orders, even after you explain to them that you will never ever need 3000 of the things. You have to have them ship you the stuff as an eval kit for free. :)
So write another book. Article I section 8 of the Constitution says "limited times" - the fact that you believe you're entitled to royalties from such a book for your entire life shows just how perverted this law has become.
By writing another book, you're doing your part to "promote the progress of science and useful arts" just as the authors of the constitution intended.
Chuckle, cough, roll eyes.
It's passive. No power needed. Basically, a wave received from one antenna will travel down a transmission line to an antenna connected at the other end and radiate out (and vice versa) with very little loss.
At least in Washington state both Qwest and Verizon will automatically put you in the phone book when you buy a phone line. You have to pay a monthly fee to get an unlisted number.
That's clearly not opt-in.
Oh, and "800mhz" cell phones typically use the AMPS analog cell bands at 824.04MHz-893.7MHz, so it's more like 33.5-36.3cm.
If one were really serious (ly-screwed-up IMHO) about this, one could construct their home as a Faraday cage. Just lay chicken wire around the entire frame (through the double-paned windows and attached to the steel doors' frame, and use conductive weatherproofing in the door jambs) and connect it all together (solder/weld/twist all points of all corners together) into one giant grounded box. All RF with wavelengths less than about one-tenth the gap of the chicken wire will be blocked (the same principle is used for the window on your microwave oven, it's also why you can see through some satellite dishes). If you want this home to have power, you'll want to hook the breaker panel to a large iron-core transformer which will act as a low-pass filter. A similar low-pass filter can be used for the phone line.
Such a home would be unable to recieve TV or radio, DSL or power-line networking would never pass through, cellphones and government-planted transmitter bugs would be dead inside, and you wouldn't have to worry much about lightning strikes either. Of course it would be cheaper to move out into the boonies.
Pure bliss huh?
*groan*
Not to me. I've seen the same 30-40% increase copying data between two disks on the same IDE chain as opposed to the exact same two disks on different IDE chains ever since UDMA support came out.
Chances are, your computer's power supply already does AC->DC->AC->DC, even without the UPS. 60hz magnetics are very large/heavy so almost all modern power supplies first rectify to 120V DC, then invert to an intermediate voltage at 20khz or so.
Anyway, would you want your UPS to need 12V, 5V, 3.3V, -5V and -12V battery sets? Would you want to have to modify it everytime Intel decides power supplies need a new connector?
The article prompted me to check this - it appears Outlook 2000 + IE5.01 at least does not send any Referer data when opening a URL sent as normal text in an email (which Outlook presents as a link). I'm very curious why ZDNet said that...
Acceleration is actually any change in velocity.
Absolutely. Amateur radio operators have worked earth-moon-earth on 144 and 440mhz for decades - there's no reason someone couldn't build the equipment to do it on your frequency. However, the antennas and such are rather obvious-looking. Any nation's communications commission would be able to spot one of those very easily in case it needs to be hunted down, and it does raise the bar beyond what most crackers are motivated to do.
In general, how do receivers handle multiple command carriers (would there be too much noise to command)?
The mathematical formula for this is Shannon's Law. Run your numbers through it (and keep in mind some modulations have significant inefficiences of their own). I can't imagine missing a couple communications windows with your satellite would be the end of the world, though.
For something with the replacement cost of a satellite, you want guarantees, not estimates of society's intentions. If you want your control center to be the only station capable of transmitting commands to the satellite, your satellite needs a way to make sure it's the control center that's doing the sending. If you want to make sure your telemetry data is from that satellite, you need to make sure it's the satellite that's doing the sending. Note that encryption isn't really needed here (a cracker knowing what you're doing with the satellite doesn't help much, as this is not a spy satellite) but some form of public key signing should be employed. It also guarantees that your control messages won't arrive corrupted (although I'd imagine you'd already have something to protect against that).
For those that would like to put an 802.11b antenna on their roof without worrying about weatherproofing their access point, this may be just the thing.