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Low Voltage Power Distribution?
thesp asks: "As I look around my apartment, I am continually struck by the plethora of high-voltage AC to low-voltage DC power adapters I use to power my various devices. At a recent estimate, around 30% of the power consumed in my house is via these adapters. From my laptop to my digital music player, and from my mobile telephone to my PDA, each device is down-converting its own power through its own adapter. Double this number to include my partner's devices. Many of these run hot, and are inconvenient to remove/replug to conserve power and outlets. Does Slashdot know of any moves to standardize power delivery to such devices, or of hobby/home-brew projects to distribute low-voltage power from a central power converter? Alternatively, are there reasons as to why this would not be a simple and effective solution to the proliferation of wall-warts."
"On closer examination, these adapters seem to fall into four major categories, 7V, 5V and 3V, with the most common being 5V. Despite this, each device uses a different DC plug configuration, which makes efficient use of adapters difficult. It seems to me that, just as AC power is standardised, portable electronics power requirements should be also be standardised, with a standard wall outlet and car outlet at, say, 5V, and a standard device cable and interface. Electronics manufacturers would save money on power adapters, and the consumer would have the cost of the converter written in to home construction or automobile construction costs. No longer would we have to lug 4 separate power adapters with us on an overnight business stay to power our various equipment."
Article is a dupe...original discussion can be found here, which amusingly enough, is itself a dupe of this discussion. Even more amusing is the fact that all of these submissions share the same editor.
Way to go, Cliff...a dupe hat trick. Zonk has nothing on you.
____
~ |rip/\/\aster /\/\onkey
Good luck distributing 5Vdc over any distance.
I agree, this is a big problem that I have considered as well. The problem of course is that there is no standard.
I was however encouraged once when visiting a high tech summer house located off the coast. Though there was no electricity, they had a rather ingenious power system. A small windmill attached to a battery powered DC haloge lights throughout the compound, with cooking provided by gas and heting with wood.
It got me thinking, wouldn't having a low power DC system be rather energy efficient? Lighting and electronics with standardised DC, cooking with a 220AC and heating, well, oil or district.
Sounds good to me!
Some say he is made with ascii, others that he is eyeballed daily by millions. All we know is, he is known as the Sig
I read somewhere about new poweroutlets that have "Universal AC/DC Adapters" built into them. They looked kind of neat, they had your regular outlets, and a retractable DC cord with multiple connectors on it. That would be much more efficient than distributing 5V around a house.
If you like what I've said here, and want to read more, go to http://www.krillrblog.com
Just a hunch, but my best guess is that we will slowly see the USB power "feature" become the standard for (very) lower power devices. You can already find cell phones, mp3 players, cameras, PDA's and a few misc. accessories that are USB powered - and I've seen USB "power only" hubs available for charging these devices while you're on vacation.
The natural next step is for more devices to switch to USB power. Routers and hubs and other things that are typically "near" a computer come to mind.
1. You can't (simply) transform DC voltage to a different voltage. This can be done very efficiently with AC. The 120v to 5V (or whatever) in your power supply is done before the AC is rectified to DC.
2. Low voltage == High losses, esp. with DC.
TODO: Something witty here...
Power is transported at high voltage to diminish losses in cables, any long-range transportation with low voltage is inherently lossy.
This would be a very bad thing. USB was never designed as a power source, and it's not good to use it as if it was.
43rd Law of Computing:
Anything that can go wr
fortune: Segmentation violation -- Core Dumped
Check out iGo, sold at Radioshack =( but manufactured by Mobility Electronics =) which is based in Phoenix (hence the smiley face...). May be helpful...
Care to back that up? It sounds handy to me, and it's not like providing power through USB isn't included in the specification.
The 12VDC cigarette lighter plug is a de-facto standard. Redo all your devices to use 12VDC with a simple voltage leveller - eg, a zener diode followed by a 5V regulator IC - and then standardise on cigarette lighter sockets throughout the house.
Wrong! Google HVDC... there's plenty of DC power distribution (read: across many km).
Actually, such a change would cost manufacturers a huge amount, because they'd have to retool every gadget that doesn't fit the new standard!
Getting people to accept new standards is hard, even when there's a cost or safety benefit. Wall power is standarized because the system wouldn't work without it. That's obviously not true for DC devices.
"Care to back that up? It sounds handy to me, and it's not like providing power through USB isn't included in the specification."
/that/ handy. USB provides power for a reason - to allow small devices to draw their required power from the host, and not require extra cables. It was never supposed to be used for solely supplying power. To have all your routers and other small devices plugged into your computer for power does seem a little strange to me, especially if you need them where there is no computer with USB connectivity (my router is across the room from me, and plugs into the wall there. It would be crazy for me to extend a cable along the floor and use USB to power it). To resolve this one might come up with a sort of USB hub that plugs directly into the wall and supplies power only, and no serial connection, but if you're going to go to those lengths, why not create a new standard and design it for powering things, instead of re-using an old standard?
Firstly, I see that I mis-read the original post. I didn't see the part about "very low power devices", but I think my point still stands.
It does sound handy to use USB for powering small devices, but not
Powering devices like LED lights that require a tiny amount of power to operate is okay, but when you move on to devices that would otherwise require a wall-wart (like the OP was suggesting), you're (ab)using USB for a completely different purpose to what it was made for. The USB specifications state that the maximum voltage that should be drawn by a single device is be 5.25 volts. Just looking around the room, I can find plenty of things (for example my network switch) that require more than that.
I am not suggesting that a universal power connector would be a bad thing at all, in fact, I can imagine that it would be hugely useful, but there are a couple of reasons why I doubt the emergence of such a thing.
Firstly, manufacturers can make a small amount of profit by making 'proprietary' plugs, because if you lose the one that came in the box, you have to go back and buy a new one instead of using a spare that you may have lying around.
Also, if all the connectors looked the same, then you would get people plugging the wrong type in and breaking something, and they'd complain about that.
43rd Law of Computing:
Anything that can go wr
fortune: Segmentation violation -- Core Dumped
mod parent funny. nice catch. and I do agree there's nothing wrong with it.
Technically USB was designed to provide power, however, the limitations do preclude supporting many devices, since there is a 500mA limit for "high power" devices. Many devices need more than that. A group of devices would likely draw more than the source could provide, in any event. So, I agree USB is not a viable power distribution option.
http://www.usbdeveloper.com/UnderstandUSB/underst-- Dan Jenkins, Rastech Inc.
yeah, did you mean to add 12v to the list?
the real reason is already stated, efficiency of power distribution.
-Tim Louden
At a recent estimate, around 30% of the power consumed in my house is via these adapters.
You're new here, aren't you. By "new", I mean, new to this planet. Apparently you have no idea how much a TV uses, or how much a refridgerator or microwave uses.
So this article is a "tripe", and also has a stupider premise than the others. Thanks, "editors".
I want to delete my account but Slashdot doesn't allow it.
Standardized connectors. It's one thing to have a variety of devices that use different voltages, but having a variety of 5V devices each of which uses its own style of plug & jack defies all common sense.
For that matter, even on devices that use the same voltages and connectors, there is no standardization for polarity! Is it really that difficult to agree that ring is negative, and tip is positive, or even vice-versa?
Adaptor lock-in is just plain obnoxious.
There's a Starman, waiting in the sky / He'd like to come and meet us, but he hasn't got the time.
3-phase AC is much more easily converted to DC, and also allows for simpler and more efficient motors. (So it is also ideal for things like air conditioners, refrigerators, furnaces, and such.) Overall, I think the advantages far outweigh the cost of an extra conductor, and it is unfortunate that it isn't more common outside of commercial settings.
Toward the end it lists many HVDC installation spanning distances up to 1100 km and power up to 3150 MW.
While I'm sure that most power (units of MW*km ?) is transmitted as AC, HVDC provides more advantages than just avoiding power losses in capacitive underwater transmission lines.
From Wikipedia:
* Undersea cables. (e.g. 250 km Baltic Cable between Sweden and Germany).
* Endpoint-to-endpoint long-haul bulk power transmission without intermediate 'taps', for example, in remote areas.
* Increasing the capacity of an existing power grid in situations where additional wires are difficult or expensive to install.
* Allowing power transmission between unsynchronised AC distribution systems.
* Reducing the profile of wiring and pylons for a given power transmission capacity.
* Connection of remote generating plant to the distribution grid, for example Nelson River Bipole.
* Stabilising a predominantly AC power-grid,without increasing maximum prospective short circuit current.
It seems to me that, just as AC power is standardised, portable electronics power requirements should be also be standardised
TYPICAL Euro-troll. Why can't everything be the same? (i.e. the way I want it) Isn't everything arbitrary> (so why not MY whim)
Other nice things:
One world currency
One world religion
One world governing body
One world form of government
New World Order
I want to delete my account but Slashdot doesn't allow it.
IANAP, and I'm not good with anything hardware-related, but... isn't one of the reasons that you'd need thicker cables for lower voltages? When the voltage goes down, the current goes up, and thinner cables would melt. I distinctly remember being told that that's at least part of the reason why long-distance power cables uses voltages in the hundreds of kV range.
:) (Of course, don't do this at home, at least not until you know what you're doing and how to do it safely.)
There's also neat experiments you can do in school with transformators - put a coil with, say, 5000 windings opposite of one with, say, 5, and you'll be able to quite literally melt nails.
quidquid latine dictum sit altum videtur.
USB 2.0 Spec download
Read 7.2 of usb_20.pdf
Devices default to low-power and as such can only pull one "unit load" (100mA.) If a device is configured to be High-power, it can draw five "unit loads" (500mA.) This is at 5V, so it will supply about 2.5W to a device (if you are lucky.)
IEEE 802.3af (better known as Power over Ethernet) would be a much better solution for the applications you mentioned (routers and hubs,) as well as others including IP phones, IP security cameras, and RFID tag readers. It provides power at 48V and around 15W. More info can be found here.
There are two types of people in the world: those who divide people into two types and those who don't.
If you have a cluster of devices of all the same voltage at the same location, then it would make sense to have a common power supply. Otherwise, it makes more sense to use a higher voltage for distribution purposes. The electric utility generally brings power down to your street in the 11kv to 14kv range, and a permanent transformer drops it down to the 120 to 240 volt range you get into your home. Distributing power at 240 volts would not even be considered beyond at most 100 to 200 meters. Every time the voltage goes up by 2, the distant can go up by 4 since the current is cut in half, which means the voltage drop is cut in half, which has even less effect on twice the voltage. When they run the voltage at 50 to 100 times as much, they can deliver power over substantial distances. Cutting voltage to 1/10 as much means you can deliver the same amount power to only 1/100 the distance.
Incandescent lights actually work better at lower voltage, especially for bulbs of lower wattage. Normally a low wattage bulb requires greater resistance in the filament. That means the filament must be longer and/or thinner. That means it is more prone to mechanical shock damage. It also has to run at a lower temperature, producing a more orange light (which in some cases is what is desired). The lower temperature wastes power since more is emitted as infrared instead of usable light. By changing the bulb design to a low voltage like 12 volts, the same power level can have a shorter, thicker, hotter filament, which can run more efficiently, even making up for the loss involved in having a transformer converting the voltage.
The reason I mention low voltage lights is to point out that they are rather standard at 12 volts (a few use 24 volts), yet transformers are generally located close to where the lights are, rather than in a central location which would require the power be distributed in low voltage form. If a central low voltage source were practical, low voltage lighting would be the first to use it. But with very few exceptions, they don't do it this way.
I once considered running lots of stuff in my house on lo
now we need to go OSS in diesel cars
Yeah, standardization is just a Satanic conspiracy.
Like that one time, Satan decided that all railroad tracks should be the same distance apart, so that every train could work on every track, so people would ride around on the trains, which sucked out their immortal souls.
Oh, and then they standardized screws and bolts, so that you didn't need to carry around one screwdriver for each screw manufacturer, which put some screwdriver makers out of business. Their children were thrown out to starve in the streets. Satan watched, and he laughed.
And home power standardized on 120V AC, so that everyone could plug their computers in anywhere, allowing Satan to tempt everyone with porn.
Don't even get me started on what Satan thinks of the USB 2.0 interface.
You want the truthiness? You can't handle the truthiness!
I've thought about the same thing for years. It seems to me that a standad DC cord, with several connectors that would provide various voltages at specified currents, could make a lot of opportunities available. Standard DC transformers, with several outlets, could be used. Planes, etc., could provide standard plugs. Conference tables could be built with plugs provided for each seat. Battery replacements would look like standard batteries, with a cord that would plug into the standard outlet. Etc., etc. It seems to me that the place to pursue this is IEEE. I don't think Slashdot can help.
I have a 2,000 Ah deep-cycle battery bank charged via PV panels and wind generators. Because the distances from source to consumers aren't great, I elected to go with a 12V instead of 24V or 48V system.
Because of my work I'm lucky enough to get cable at no cost, so I over-specced it: 25 sq mm from the cells to the regulators, and 16 sq mm from PV panels and wind gens.
Lights are low-consumption flouros, and computers, radios, etc are direct from the supply. Cooking and heating is gas-powered, except water which is solar heated.
The few sub-12V devices I have are powered by custom controllers at the distribution board.
No problems or outages so far, and no bills from a powers co. The initial outlay isn't tiny, but I feel it's worth it in the long term, even in the satisfaction-value I get out.
I agree, 2.5 Watts isn't a whole lot of power with which to play. Technically, USB isn't a good choice. But because USB is already everywhere, I really think that it will inevitably be the closest thing that we have to a low power standard. There's no extra equipment required, and it's incredibly flexible -- it's pretty cool that with all the PC's around the house and office, I'm seldom more than 30 feet from a USB "charging" or "power" outlet. For longer term use, I imagine that cheap USB power hubs will be readily available. Plus, there's no reason for "wall warts" with USB connectors to cost more than any other 5V power adaptor (excluding a few dimes for the slightly more complex connector).
What would really make this work is some sort of higher power extension to USB, as you say, something in the range of 15 W. Heck, a 17inch LCD is right around 20W (I think)... maybe in "USB3".
Satan was surely responsible for RS-232, and he's getting his britches into USB 2.0. Ever seen how many USB connectors and cable combinations there are?? It's RS-232 all over again. Some speculate that life on Earth is already hell. It isn't. Hell has no hope. Purgatory, on the other hand, gives you hope. That's why we keep clutching to new standards, because surely THIS one will solve all the old one's problems.
-russ
Don't piss off The Angry Economist
Have we all forgotten what companies charge for $2 wall warts? I've even seen a Brother label maker wall adapter that has an odd voltage (7.3v), odd amperage, a non-uniform center pin, and inverse polarity. They go overboard with the accessory business. This particular wall wart costs $24 at OfficeMax. Then another $18 for the label cartriges. Then there are the power-hungry devices like cameras that don't come with a wall wart at all (computer controlled, time interval shots). Us mere mortals have to guess when we go down to the store what size connector to use. Face it, the money is in the connectors. If they can find a cheap way to make you use a new connector and charge outrageous amounts of money for adapters, they will. Cheer up. Atleast your iPod doesn't have any custom connector on it. Oh, wait. Never mind.
So maybe a better solution would be a single brick with different connectors for different voltages - this would conform to ISO standards. Then they could just pull the old printer "this box contains no cables" trick, and it would reduce the number of unused transformers out there eating away at copper supplies.
> To resolve this one might come up with a sort of USB hub
> that plugs directly into the wall and supplies power only,
> and no serial connection, but if you're going to go to
> those lengths, why not create a new standard and design it
> for powering things, instead of re-using an old standard?
If there was any chance of this to happen then it would have already happened one or two decades ago. I see the obvious absence of such a standard as a very good proof that creating such a standard is not in the interest of the gadget manufacturers.
But with usb powering it is an entirely different story, manufacturers include the usb power option not because they have been waiting for a low-power plug standard all the time but because the devices need usb connectivity anyways and if you already have that then it's just convenient to have it as a power option too.
And being able to charge your phone, camera, mp3 player or pda virtually anywhere where power is available without bringing a vendor-specific cable would be such a great thing, sadly we are not there yet, most of those toys do not come with a standard usb type "b" jacks but need custom adaptor cables. and taking a powered hub + _one_ wall with you while traveling is definitely less of a mess than one for each device (multiply wall-warts by two for in-car power supply, but soon we will see usb blugs in cars, only for attaching mp3 media first but i guess once that becomes mainstream people/carmakers will soon understand the usefullness of a whole array of usb jacks under the dashboard, for powering stuff)
Oh, and i'd bet that before we see a specialized low-voltage short range (the first implies the second) power distribution standard that actually makes it to widespread real world use we will see an usb specification that is updated to the needs of more power-hungry applications, like quick-charging batteries.
[i have an opinion and i am not afraid to use it]
I for one welcome our new globally conspiring standardized power overlords.
Buy one beefy transformer for your common DC voltages - start with 5 and 12 - at Radio Shack. If you are enterprising, you could also repurpose a PC power supply for this task. Then buy a couple of these adaptaplug extensions. For each device, buy the appropriate adaptaplug connector for that device, and a "y" connector. Use Y connectors and extensions to daisy-chain as many devices as you need to the appropriate voltage chain (careful not to go too long on the wires though), until you reach the current capacity of your transformer. For those pesky devices that have the cord attached inside the device, just lop off their crappy wall wart or connector and solder on a hobby connector.
If you don't know where you are going, you will wind up somewhere else.
I envy you if your devices fall into three major categories. I've been toying with the idea of building an equiptment rack with a few DC power buses for things like my DSL modem, TV antenna amplifier, mic preamp, router, various chargeable devices, etc. In addition to power, the rack would provide real power switches; many of my devices lack power switches. Since all the equipment will be in the same rack, transmission losses should not be great. Now, it may be the case that most of these devices can handle a fairly wide range of voltage input, but the provided adapters I've checked thus far include (DC unless otherwise noted): 16V AC (DSL modem and mic preamp), 16V (laptop), 15V (speakers), 12V (router), 7.8V (camcorder), 5V (TV antenna amp), and 4.3V (camera). My goal now is to have 120V AC, 16V AC, 16, 5, and one or two adjustable voltage sources. This isn't much better than individual transformers unplugged when not in use.
By the way, if anyone knows a supplier of small quantity panel mount voltmeters and ammeters of so-so or better quality that don't look like ass, please speak up.
To be honest, I still can't imagine why it was necessary to invent Firewire and USB. Ethernet was already ubiquitous when they got popular and the chipsets were already cheap. If the IC industry could simply have invented some new protocols (e.g. for some of the Firewire capabilities) and a new connector (e.g. to provide power, like USB) they could have re-used existing chips and drivers to give us completely new functionality.
Honestly, how many serial buses do we need?
Sit, Ubuntu, sit. Good dog.
I've been considering this since the last time this was on slashdot. While over any real distance DC is inefficient for power transmission, the inside of a rack might benefit. I figure with a large UPS and some sort of redundant power-supply, you could feed a number of computers with 12V lines and a picoPSU-120 12V DC-DC ATX power supply. Has anyone tried this yet? I've never worked with high-density hardware (like blades) but I'd imagine that each blade is certainly not using its own PSU.
what the hell is a 'junk character', anyway?
Friends don't help friends install M$ junk.
Since DC current can't travle far - you should really only convert to DC at each outlet. That accounted for - there's no reason we can't settle on 12V DC as it's already standard in the car and is even offered on buses, trains, planes etc. To convert at the outlet to 12 DC car plug you need this:4 .8956.1.html
c tId=2102590&cp=&kw=dc+adapter&parentPage=search
http://www.nugadgets.com/products/ProductDetails/
if you have multiple devices you'll need a spliter:
http://www.outletpc.com/c6331.html
if there are any devices that didn't come with a car adapter you can use one of these:
http://www.radioshack.com/product/index.jsp?produ
Of course higher power versions of these cost more....
Honestly, how many serial buses do we need?
Many. I'd rather not get into it, but I'd say most of the serial protocols listed on this page bring something different and necessary to the table. (Price/Speed/Expandibility/Fault Tolerence tradeoffs) To sum it up, you wouldn't want to use a serial protocol capable of 10Gbps over 100Km of fiber to communicate between your keyboard and your PC.
There are two types of people in the world: those who divide people into two types and those who don't.
As some may know, this standard provides for approximately 15W of power at a nominal 48V. See http://en.wikipedia.org/wiki/Power_over_Ethernet for an introduction.
We can reuse and/or extend the probe/negotiation phase to provide additional power levels, let's say up to 150W (approximately 4A max).
Advantages
1. Enhanced safety because unused outlets provide a high-impedance (power-limited) source2. Unified power connector for low-voltage/low-power appliances
3. DC outlets could be provided either through centralized power controllers, plug-in power strips, or wall-box mounted controllers
Disadvantages
1. Power controllers will always waste power2. Centralized power controllers will require point-to-point wiring
3. Significant additional component cost compared to linear regulators
4. Modest additional component cost compared to DC/DC regulators
Some device manufacturers won't want to support this because it would increase the size of the in-device charge controller. For example, I have an iPod, a Treo, and a Bluetooth headset. All support a wide range of input voltages for charging (this implies an internal DC/DC regulator), but none support an input voltage higher than approximately 15V. Designing a DC/DC regulator that supports 48V requires more robust (therefore larger) components. In addition there will be an in-device power controller to communicate with the central power controller. Fortunately this last part is already available for 802.3af applications.
You heard it here first.
One true ring!
Because this Slashdot article is so frequently accepted, just rewrite it a little for "many serial buses" and ask everyone for a serial bus solution.
One way to fix this problem is to just STOP buying weirdo voltage appliances and stick to 12 VDC.
The mobile/trucking/marine/RV alternate energy market is full of neat stuff that runs off of 12 volt natively. Just about any gadget you can think of. Around the home then it's not too hard to run separate circuitry, or on the cheap and easy to pull off, stash a few 12 volt (mat/gel cells probably) batts, one in each room you want to have that power in. A cheap float (not trickle, "float") charger is all you need then..that's the cheap way, there are others, but that's enough to get you going. I keep one big truck batt under my desk for immediate use when the power goes out. I can slap one of my old laptops on it that has a built in 12 volt input and be back on the net within minutes. Also have a TV, some radios, a room light/drop light, etc.
I try to avoid devices that use propietary built in batteries, they *suck*, for me they have to have "standard" sizes,AAA, AA, C, D or else they have to be 12 VDC. I can't say I am all pure there, but pretty close.
And that is one of the things that whizzes me off about the damn cellphone companies, there outta be a law on standard batts for them things. Jerks, screw you on replaqcement batts to make you get a new phone all the time. Bastiges. Or make them take regular batteries. I have a nice transceiver that can take regular AA alkaline batteries in the powerpack OR you can add two more of the rechargeables (they are usually lower voltage, 1.3 volts as opposed to 1.6) to get the same voltage. Your choice, neat.
most of the serial protocols listed on this page bring something different and necessary to the table.
I'm not sure I can agree with you, there. Don't get me wrong: I'm not trying to suggest that one size fits all. I'm just saying we have way more than we need. For instance, I'd love to see ATA over Ethernet or HyperSCSI replace Fibre Channel and Differential SCSI in the data center. Instead, they've created yet another serial bus, Serial Attached SCSI. I realize AoE and HS are experimental, but if they had some industry backing, they'd mature in a hurry.
To address your other statement:
you wouldn't want to use a serial protocol capable of 10Gbps over 100Km of fiber to communicate between your keyboard and your PC
True, but 10M Ethernet was plenty mature when USB was invented and, with the addition of PoE, would have fit that niche just fine. (I don't mean to suggest the Ethernet is the end-all and be-all of serial buses, either, but it's a good example of hardware that's cheap and everywhere.)
It just seems like the industry keeps re-inventing the wheel and making it difficult for their customers.
Sit, Ubuntu, sit. Good dog.
You probably already use plug strips that have a switch on them. While it may be inconvenient to plug/unplug them on a regular basis, it's rather easy to hit the power switch. Just get 2 or 3 strips and categorize the plugs. One for things that have to stay on (answering machine), one for things that are only on while home or only when awake (router, dsl modem, cordless phone), etc.
When you leave home, hit the switch. When you go to bed, hit another switch. When you're getting busy in the bedroom...oh wait this is slashdot nm.
Distance is still a problem.. why do you think that you have a big fat wire on your car battery? A lot of car manufactures are looking at using 47v or something for cars in the near future to reduce the weight of wire in cars.
-- I have a private email server in my basement.
Darn, I forgot to mention in my previous message: that's a very cool link. Thanks.
Sit, Ubuntu, sit. Good dog.
I wired it all up and: 16 watts again.
It was exactly the same between using all the individual supplies and using the centralized PC supply. Admittedly, 16 watts isn't exactly ideal for a 90-watt supply (hmm ... maybe I'll try a smaller source supply ...) but at least I get a nice solid 5 volts going to the USB hubs.
If you get one of those Kill-A-Watt (or equivalent) meters, it's a great help in figuring out what you might want to put on a power strip and switch off manually. My stereo components when off drew a total of about 50 watts so I started switching them all off. The battery chargers in the basement used about 10 watts total, but since I was only using them to keep batteries topped-off, I could reduce it by putting them on a timer and running them an hour a day instead.
In essence, do your experiments and figure out how much you'll really save.
--- Jason Olshefsky
Karma: Poser (mostly affected by adding this line long after everyone else did)
If % Power loss = Power * Resistance / Voltage Squared then when would % power loss = 100%? In the given example, 100% = 120W * 10 Ohm / V^2 when V = sqrt(1200V) Hmm, that doesn't sound right. 100% power loss means no power gets to the destination, right? Does that mean no electrons will reach your house in this scenario? Here's another one. Another poster said P = I ^2 * R so as the current through the transmission line increases, so does the power dissipated by the transmisstion line. but P = V^2 / R so the same could be said about voltage. What is actually happening is that there are two resistances connected in series: the resistance of the transmission line (R1) and the resistance of the load (R2) (your laptop or whatever). If both resistances are equal then both dissipate the same amount of power, but if one is larger than the other, then the largest resistance will dissipate proportionally more power (I.e. R1=1ohm, R2=9ohm then R2 dissipates 90% of the power.) So the load should have as high a resistance as possible in order to get as much of the available power as possible. But if the load has a high resistance then a high voltage will be required in order to push electrons through the load. The first equation could have been corrected by taking into account the difference between power into the system (from the power plant) and power used by the load (your laptop). For another confusing read, check out http://en.wikipedia.org/wiki/War_of_Currents
As a BSEE, AND I do lots of house wiring (pay is good, I like my boss- ME!) I think this is feasible, but may be impractical. As noted above, most low-voltage devices, say under 20V, use fairly low current. My hungry Athlon-based laptop wants almost 5 amps at 18.5 V, but even that is no problem for say 14 gauge wire, which is rated for a 15 Amp 120 V circuit.
/. article on the growing scarcity of Cu. Yes, I recycle my scraps and so do many electrical contractors.
Additional circuits would have to be run in houses, and copper wire is getting very expensive (not to mention the cost of my installing it!) A year ago a 250' roll of 12 gauge was about $32, now it's over $55. I don't have the link, but I think I remember a recent
Amps are "drawn" by a device. The power supply provides voltage and makes current available. The device draws the current, as in Volts / Ohms = Amps. So a centralized DC system would need current limiting on each port so that a wayward (broken) device doesn't draw too much current and cause a fire in the device. This would be a major problem. You could do current limiting, but someone would have to set the amount for each device.
And obviously the voltage and polarity would have to be set too.
A possibly much bigger problem would be that most devices have some kind of electrical interface which connects to other devices, like A/V wires, USB, FireWire, etc. The devices usually have one of the power supply connections connected to the device interconnect ground pins, and not necessarily the (-) pin. Power bricks provide an isolated power source so that device designers can ground (+) or (-). It's usually (-) but there is no guarantee. The result could be lots of sparks and smoke!
I think a great product would be a multi-output power supply with 6 or 8 isolated outputs with switchable output voltage and current limiting. It would be a pretty easy design project, and I could envision it being programmable through a USB port. Anyone want to start a business?
Recently, I did my own experiments on low voltage power distribution, mainly because I plan to install a large scale solar power charger with a lot of Pb accumulators. The best result is: 24V/35kHz AC home backbone, with a lot of switching voltage changers on rooms, those provide multiplicity of output voltage of 5V, 6V, 9V, 12V DC as well as 230V/50Hz for UPSes and consumer grade devices. LED lights are quite fine with low voltage already. It will take some 6-9 years to return the costs, but only because I design and build the circuitry myself.
Unlike DC or 50/60Hz AC, 35kHz (or even more) AC requires a lot cheaper wiring, very small transformers and have very little losses.
There you are, staring at me again.
USB PlusPower was developed in the late 1990s by IBM, Fujitsu and NCR in response to retailers' demands for self-powered cash register peripherals. Cash registers have several peripherals that require more power than USB alone can provide -- scanners, vacuum fluorescent displays, scales, PIN pads, printers and cash drawers all demand more current than a USB port can provide.
Most cash register stands have at most two electric outlets wired beneath them. In many locations electrical codes and fire codes prevent commercial building tenants from permanently using extension cords, octopusses or power strips. New outlets can cost anywhere from $100 to $1500 to $5000 each to install. So the retailers refused to accept a USB equipped cash register that required half a dozen wall warts, and told IBM (and the other vendors) to come up with a better solution. USB PlusPower allows the cash register's power supply to provide all the power required on all the devices, no rewiring required, no external power cables, no wall warts.
I'd love to see USB PlusPower ports on my home computer. A quick glance with the flashlight just revealed over a dozen wall warts under my desk. A charger for my camera, three powered USB hubs, speakers, cable modem, router/firewall, two scanners, three printers, a weather station, a TV tuner, a Palm charger plus a couple others I don't recognize at the moment. My power supply can deliver 500 watts, and it's currently drawing less than 200, so I know it's got ample capacity to drive the rest of this junk. There's just no good way today to get the power from it to the devices that could use it.
Sadly, the USB PlusPower spec seems firmly planted in the POS space, with no driving force to push it to the consumers' PCs. The spec itself is moribund, not having been touched since 1999. Now, if consumers could somehow unite to demand a replacement to the dozen wall warts we all seem to suffer from, we could have something like USB PlusPower start showing up on high-end machines and motherboards. That would be incredible.
John
It seems like USB, FireWire, and Ethernet have now almost converged to do the same thing, but it wasn't always like that. Remember that almost 10 years ago USB was 12Mbps, FireWire was 400Mbps, and Ethernet was up to 100Mbps but was unpowered and expensive.
Even if power-over-Ethernet existed back then, it wouldn't work. It's 48V because it has to power IP phones (up to 15W) over long runs (up to 100m). If every USB device had to run on 48V, every single USB hub/port would need a 5V-48V converter and every single keyboard/mouse/flash-drive would need a 48V-5V converter. This would increase the cost, power usage, heat dissipation, and size of every USB device.
And don't forget that Ethernet is still an order of magnitude more expensive than USB. Sure, an Ethernet chipset might be only $1, but a USB chipset is only $0.10. Nobody's going to pay double the price for a mouse just because it has a fancy new mouse-over-Ethernet interface.
Ethernet is a great networking protocol, but it is not a good data bus. It is only now that it's running at 1Gbps full-duplex that it's being adapted for things like disk protocols.
Now do we need both USB2 *and* FireWire? Probably not. Do we need FC, SAS, *and* SATA? Probably not. But I do think that we'll be needed separate buses for peripherals, storage, and networking for the forseeable future.
dom
We all owe a debt of gratitude to the USSR for fighting Satan on that one...
Really? I was confused by the fact that I need 20 different screwdrivers to disassemble a damn stereo...
Satan must stick to the USA, since most of the rest of the world goes for 240V.
That's my favorite, of course (good old European politics), but a close second is the split over digital TV standards.
Slashdot gets worse every day... Pipedot: News for nerds, without the corporate slant
I've also wanted to do this for a long time. It's been a lot of work over several years, so I'm not sure if it was a worthwhile obsession, but I have combined a DC power bus with battery backup and supplemental solar power.
http://ecloud.org/index.php?title=DC_power_system
Actually I believe there is no incentive for manufacturers to standardise wall-warts/connectors, because currently they sell lots of highly profitable plugpacks as accessories - one for every device! It's a license to print money compared to just selling the consumer one plugpack.
For every expert, there is an equal and opposite expert. - Arthur C. Clarke
Many telecom devices use 48V DC. Not only PoE-devices. Vendors of consumer electronics should move towards single 48V standart. This is not a problem today because efficient DC voltage convertors are common. This will allow us feed all those wireless routers, cable modems, speakers, phone chargers et cetera from single 48V power bus.
Seven years ago I was a student in Riga Aviation University. Each room in every university building had three sets of power outlets: ~220V 50 Hz, ~115V 400 Hz and DC 27V because airplanes use these voltages and almost all aviation-related devices required them. I think that every aviation-related buildings across ex-USSR has these three power grids. Do other countries use the same system in aviation training centres and labs?
definitely won't work. The power (actually current) limitation is due to the size of the wires and current carrying capacity of the "RJ-type" connectors which must be assumed. One cannot safely provide anywhere close to 150 W of power. There is a new specification in progress (802.3at, aka PoEPlus) to allow delivering more power, but the practical limits are on the order of 30 W using 2 pair, 45 W using all 4 pair.
"National Security is the chief cause of national insecurity." - Celine's First Law
A question of DC vs AC for electricity distribution was the subject of conflict between Edison an Tesla in 19th century. You can read more on that:
/ >
<URL:http://en.wikipedia.org/wiki/War_of_Currents
When I worked with Homer at the Nuke Plant... HVAC=Heating Venting Air Conditioning, but that is at the begining of the power struggle.
Sig Hansen?
that's damned brilliant. how come I never thought of something like this
I might actually build a half bridge DC-AC widget for my car to take advantage of this; I've got more space dedicated to wall warts than I do the computing gear its powering. USB2.0 hub... 1 cubic inch. Power supply for USB2.0 hub... 6 cubic inches.
as long as you get the harmonics right, you could probably build a nice PWM uC to do power modulation straight from a bridge, sans transformer. do it wrong and you'll be feeding your devices a most unusualy waveform, of course. I guess considering the price you can get transformers for, pretty silly idea I guess.
The voltage to amperage ratio involves higher voltage and lower amperage vs lower voltage and higher amperage, the power consumed would be theoreticaly the same, however transmission problems abound as voltage decreases. A car battery is perhaps twelve volts, supplying several hundred amps to turn the starter motor, hence the huge and relatively short battery cables. At 12 volts and 500 amps you have only 6 kilowats of power. Many "wall warts" are for charging batteries. Battery life tends to involve number of cycles and the rate of charge, so most of these tend to use very little power over several hours, vs lots of power over several minutes. Perhaps a better solution would be for electronics manufactures to standardize power usage, batteries, and charging systems, making them more interchangable, with a view to some universal charging system. Many if not most, power converters are transformers (they are heavier), so a mechanism could be included on the secondary (appliance) side to disconnect the primary (power) side, to save power, reduce fire danger, etc., when the appliance is not being charged, used, or whatever.
First, power requirements for common peripherals (small hard disk drives) exceed the
standard capacity of USB (0.5 A at 5VDC); there are some laptop plugin drives that
come with TWO USB cords, because it needs power from both ports to spin up.
Second, high power variants of the USB port (Apple tried this, on the cube, for
some high-power speakers) give rise to odd incompatibilities. Breaking
the standard is a bad idea. Trust me. I've diagnosed/dealt with it and don't
care for a repeat of THAT.
Third, there are devices that need other voltages (like EIA-232 serial ports) and
the 'universal' +5V is just plain wrong. Converters are used, of course, but
the converter isn't notably simpler than an AC power brick; you save on cables,
not on hardware. Cheapo converters for EIA-232 are energy inefficient, but
there isn't much energy required, so that's OK.
Fourth, it's cheap to make high voltage parts and expensive (in terms of chip area
and yield from a semiconductor processing plant) to make high current ones; if
you knew you were gonna convert the DC voltage, your choice of input voltage
would be higher, 48VDC (about like telephone company power handling) or the
new automotive standard, 42V. Power-over-Ethernet is standardized
at 48VDC (negative voltage) for this reason. The price difference makes little impact on
the customer, but some pennypincher engineer will always choose for you.
Then, the marketing department won't show the brick in the pretty boxtop picture.
Firewire does use higher voltage power (12 to 24V), with similar current (so the wire
isn't stiffer than USB wires). As a result, Firewire power DOES support a hard drive
with appropriate conversions inside the peripheral.
I highly recommend Anderson Power Poles as a very convenient means of distributing DC to various devices. I have a Ham Radio setup, which has a multitude of devices that all run on 12vdc (Actually 13.8v) and a large (20 amps) power supply. That supply feeds a DC "power strip" of Answerson Power Pole connectors. Each device gets a set and they all plug into the "power strip". Each "outlet" is fused individually, and there is an LED under the fuses (standard automotive blade type) to show you at-a-glance if a fuse has blown.
This "power strip" is called a "RigRunner" and it is sold by West Mountain Radio. http://www.westmountainradio.com/ and no, I don't work for them... I just really like thier products!
This 12v power distrubtion box is the best investment you can make for DC power distribution. The Anderson connectore are universal- there is no "male" or "female" connection. Thus, you can put them onto a battery pack, and then bring the battery pack with you to run a device, then plug the battery pack into the power strip when you get home to charge it. It's extremely convenient.
I have also made a few adaptors, which have the Power Poles on one end, and the standard "barrel" type power plugs on the other. The possibilities are almost limitless!
The Power Pole connectors come in various sizes, from 15 amps up into the hundreds. The ones I'm using are 25 amp.
Willie...
I've seen USB "power only" hubs available for charging these devices while you're on vacation.
As have I. And most USB hubs that provide any significant amount of power have a provision to plug in auxillary power with a.... get this.... wall wart.
Come to think of it even the nonwallwart devices I have, really switch it down to mostly 12V. Opened up various machines: PCs step it down to 12V and -5v. Routers etc all step it down to 5V or 3.3V. So its just the TV/monitor, microwave and incadescent bulbs. Even bulbs can easily run with lower voltage if you remove their resistance. The bright halogen lights use 12v or less. LCD panels use about 25V in one spot, the rest are all 5V inside. Mircowaves and CRTs upconvert power to way above 110V anyway, theres no reason why they cant do that with a 12V input.
I think all electronics as they stand today can take 12V inputs. One can wire his house in this voltage. Even better would be a setup where you'd only use 5V electronics and the wall sockets would look like female USB plugs. In your average PC, it takes 12V too but I dont know where that gets used. The datasheets of the CPU, chipset, GPU, PCI/AGP busses, IDE connectors, USB connectors etc all show 5V at best. I think its more than 5V for the monitor connector and the RS232, but who uses RS232 anyway, and I suspect the DVI connector uses 5V at best.
Thats it. I'm building a USB-socket house. Even better we can build a central switch whereby all USB devices will be connectable to any host out there, so you can switch your living room dvd player to your pc in the bedroom for control through their power sockets (5V USB). Can also use the ethernet this way so you dont need an ethernet connector either.
Possibilities...
"Give orange me give eat orange me eat orange give me eat orange give me you." -Nim Chimpsky
Either he's only looking at his Palm Pilot charger and ethernet router, or he's managed to somehow not end up with a truly representative sample. Upon closer examination, you'd also find 20V, 16V, 12V, and a few 9V. Upon even closer examination you'd also find that some of these show up as AC sometimes. Herein lies the problem. There is no "standard" low voltage. It ranges from 3V to 24V, can be AC or DC, and randomly requires one of forty-odd connectors wired at no particular polarity.
Conclusion: the Empire squashes the Federation like a bug. Accept it.
By one of two methods:
Increasing the voltage, and using DC/DC switching regulators for "legacy" hardware. (There is a push now towards 24 and 48v automotive systems, because even with incredibly thick cables, the current draws from the battery/alternator on modern cars are just getting to be too great. 48v batteries also make pseudo-hybrid systems such as GM's FAS system feasible.)
Increasing cable thickness to reduce resistance. This gets to be expensive, difficult to manage, and heavy.
There is one problem with the GP post - Incandescent lights do NOT get more efficient as voltage decreases - low-voltage incandescents tend to be MUCH less efficient than higher voltage ones. This is the main reason why (in addition to cost), LEDs have only replaced incandescents in small battery powered devices. Low voltage incandescents have horrible efficiency and horrible bulb life (10-20 hours per bulb), while 120v incandescents have much higher efficiency and much longer bulb life. (120v incandescents are more efficient than LEDs, or at least that was the case 3-4 years ago, LEDs were improving steadily though. Neither could touch fluorescents in terms of efficiency though.)
retrorocket.o not found, launch anyway?
Edison, for some unknown reason, hated Tesla and tried to kill his ideas of AC power distribution. He apparently had the (AC-powered) electric chair created as a PR stunt so that people would know that AC power was being used to kill people -- but it turned out to be relatively difficult to reliably kill people with AC power because an AC charge turns out to be an impromptu defibrulator, so you essentially have to cook your victim.
DC on the other hand, causes the heart to go into a constricted mode which is harder to recover from. I was taught to always handle AC with one hond only, if at all possible (to avoid a possible circuit across the heart).
Free Software: Like love, it grows best when given away.
Your locality (and nation) may be different, but if you are in the United States, watch out! You may be legal to build such a thing, even wire it as such, but you may find it hell to get homeowner's insurance. Heck, many insurance carriers in the US look at you funny if you so much as think about daring to be different. Look into the issues with getting HO insurance to cover such radical building systems like rammed earth or straw bale construction. Never mind the fact that both are techniques with hundreds, maybe thousands of years of history in construction, never mind the fact that if constructed right, both are way more fire resistant than a stick-frame house - never mind a myriad of things - you will find it near to impossible to get such insurance, or if you can, your rates will be extremely out of whack vs regular construction.
Don't get me started on trying to get insurance for an old school bus to drive as a private vehicle - here in the Phoenix area you have to pull all kinds of weird trickery just to get it "recognized" as an RV...
Reason is the Path to God - Anon
Build or buy a few DC power supplies delivering about 12 V and a sufficient number of amps, with a number of Powerpole outputs. Then build a connection cable for each device, containing the following, from end to end:
The proper plug can be obtained from the original power supply. For travel, get a 12 volt wall wart or two, install Powerpoles, and you can use any device you have cables for.
(If you still do want to use the original supply for its intended purpose, just add a few connectors (preferably non-Powerpoles to avoid costly mistakes): female on the originall power supply, and on the output side of the DC/DC converter; male on the cable leading to the device plug. Mind the polarity. This does add one possible failure point, though.)
Place the power supplies strategically to balance convenience and transfer and core losses. An enterprising soul may build* several connection panels with individually and/or collectively switchable outputs.
*) A body may be required to assist in the assembly process. Should the enterprising soul not have one of its own, it is generally considered good manners to ask for permission to possess someone's body, even if it's for a good purpose.
--js--
Usage: km/h for speed (kilometers per hour); kph for very slow impulses (kilopond hours).
I've been shocked with 60 cps 120 VAC dozens if not hundreds of times. It doesn't particularly bother me regardless of humidity or capacity of the circuit. It's possible that I have a high pain threshold, but I'm certainly not a masochist. My doctor says my heart is normal, too.
For the last few decades I've double-checked 120 VAC lines to see if they were "live" by touching them with my bare hands. One hand on the neutral or ground, one finger tapping the (supposedly dead) screw holding down the hot lead. Every once in a while (more often now that I live in a building with over a hundred years of wiring by accretion) I get shocked due to inaccurate labels in a breaker box or carelessness. It's no big deal - if it was, I'd use a voltmeter, which is less convenient.
440 VAC, now I can tell you that hurts. I don't recommend taking a hit of more than 120VAC. And while some hackers will taste connectors for current (RS-232C feels like a weakish 9-volt battery on your tongue) you have to watch out for toxic metals like lead and cadmium and you should not stick a live phone wire in your mouth (if the phone were to ring, you'd have a non-fatal but really unpleasant experience).
Oh, and just because you can tap a live 120 VAC line with your finger and only feel a sharp tingle, doesn't mean you can't hurt yourself with house current. A short circuit with a metal object such as a screwdriver will produce noise, molten metal, and a flash bright and actinic enough to give you a nasty burn and a mild case of welder's eyes. And don't get yourself in a situation where high amps will be forcibly pumped through you by a collapsing circuit, I'm pretty sure that would be bad.
Presumably, you won't need cooling for his "high-temperature" superconductor.
Off-grid houses sometimes use 5/0 wire or welding cable to minimize DC losses over distance. Most of the posters in this topic are saying high voltage AC power transmission is for reducing line loss, but I believe it's more for reducing the size of the conductor needed to prevent excessive loss. If your wire had the surface area of a football field, you probably wouldn't lose much juice at all.
In Real Life [TM] that is. I don't know much about theory but I've done a few miles of wiring.
You can spot poorly designed solar gadgets, such as are sold at Home Despot and K-Mart, by the thin wiring. It should be thick thick thick if you want to squeeze all you can out of a PV cell.
This subject is constantly discussed in the alternative energy community, with the battle generally being fought between the "wrenches" (guys working in the field, who build working systems for real customers and operate entirely on empirical evidence) and the "theorists" who usually claim that what the wrenches are doing is unsafe, impossible, or illegal.
I fall somewhere in the middle; I don't have decades of experience with multiple installed systems like the real wrenches (guys like Windy Dankoff, Bob-O Schultze, Richard Perez, Ian Woofendon, etc.) but what knowledge of electricity I do have was mostly gained in the field and not in a classroom.
Another guy "in the middle" (also with far more experience than I) is John Wiles. John has been living in a solar-powered house for quite a while, but he's a researcher at a New Mexico university whose work is funded by Sandia Labs. John has made multiple recommendations to the NEC, a few of which have been adopted (they all will eventually be adopted, I predict) into article 690, which deals with PV wiring specifically and low-voltage wiring in general.
This I know: In the field, wrenches use welding cables (specific brands of it) and DLO (Diesel Locomotive cabling) instead of huge, inflexible solid or thick-stranded wiring. They've been doing it for decades, illegally, without encountering any of the problems that the theorists have convinced the regulatory authorities will surely result. The theorists generally point to a single known instance where a welding cable's insulation cracked in use - ignoring dozens of similar instances where this did not happen, and dozens of instances where approved cables also experienced insulation failure - and say "welding cables are not safe".
In Real Life [tm] off-grid systems, fatter cables work better for low-voltage runs from power producing equipment to battery boxes, and from battery boxes to inverters. Surface area seems to be a factor since more strands works better (this is not true in AC wiring) for the same weight of copper. Within battery boxes, wrenches often use copper pipe tinned and flattened at the ends to bolt together battery strings at the lugs - this is cheap, safe and effective in actual use though most definitely not to code. I personally use 3/8" by 3/4" copper bar stock jacketed with rubber hose or heat-shrink tubing for battery interconnections (because I had some on hand) and I've noticed that the local telco uses even larger solid copper bars to connect their huge glass 2 volt lead-acid cells.
"Works better" in this context means that you can squeeze more run time off your loads given a set input of solar or hydro energy (wind is usually wild AC, a whole nother problem space). It also can mean "easier to install" since stranded cables are more flexible, but that's a secondary concern really.
As for focusing more light on PVs, a well designed installation might incorporate reflection or concentration, but it's rare because it's usually not as effective as increasing the surface area under sunlight. You have to remember that reflection is not perfect (to put it another way, mirrors get hot too) and a reflector has to be survivable in real use, which means it's going to be almost as expensive as adding solar panels. The same caveats apply to lenses, only more so; a lens that can survive as long as a PV panel might even be more expensive than additional PV - and if your lens gets dirty, power production degrades much less gracefully than with a reflector system. If you go overboard with concentration or reflection, you will burn up your PVs, or you will have to buy special super-duper high temp PVs that again cost more than just putting in more panels instead of lenses or mirrors. The "browned off" PV panels you can buy cheap, that have less than half their rated output, were burnt up by reflection/concentration schemes.
Is this him? Don't much care for his website design, I must say. But I'm not much good at that either so I shouldn't really criticize!
I suspect given the NASA data on insolation of my area (rough average 3.5 kWh/m2/day, according to the site) and the amount of unshaded space on my property (roughly 100 m2 if we're being really, really optimistic) it would be pretty hard for me to get ROI from this technology. Cutting down trees would be a big mistake since the buildings would all wash away in the next flood.
Looks pretty cool for people in Oz and the US desert southwest, though.
That's him! I agree the website is terrible :) Just been reading a book called 'permaculture' by david holmgren - you might find it very interesting. You might also consider solar heating your house - 3.5kWh/m^2 day is still a lot of energy, and a cheap 4x3 greenhouse might cost you $200 in materials for 42kWh /day (what's your heating bill like?)
Here is an example of the current waveform of a switching power supply in a computer. Scroll down to diagram 8.
now we need to go OSS in diesel cars