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Wireless Power Over Distance: Just a Parlor Trick?
Lucas123 writes "Companies like U.S.-based WiTricity and China-based 3DVOX Technology claim patents and products to wirelessly powering anything from many feet away — from smart phones and televisions to electric cars by using charging pads embedded in concrete. But more than one industry standards group promoting magnetic induction and short-distance resonance wireless charging say such technology is useless; Charging anything at distances greater than the diameter of a magnetic coil is an inefficient use of power. For example, Menno Treffers, chairman of the Wireless Power Consortium, says you can broadcast wireless power over six feet, but the charge received will be less than 10% of the source. WiTricity and 3DVOX, however, are fighting those claims with demonstrations showing their products are capable of resonating the majority of source power."
i mean, the amount of effort it took you to make that rock round and then roll a log over it? you could have carried 10 logs in that time. quit with the making new shit, gorg, it isn't useful at all and it isn't like anyone will ever find a way to improve on it. ...
oh, nice vette, gorg.
Back in the day, Tesla had achieved even greater success. Though if you can charge from anywhere, how can you be billed? That is what will permanently stop this type of technology.
Have they tested its ability to charge the phone of someone with a pacemaker or other medical device? Sure, it charged the phone, but he was no longer around to make a call...
Tesla figured out how to broadcast power miles away, wirelessly, using technology available in the late 1800s. People around his lab routinely reported switching off the lights in their house, only to find they didn't turn off. Six feet? I'll be impressed when it's ten miles -- that was the standard at the turn of the last century.
#fuckbeta #iamslashdot #dicemustdie
Very cool actually, if we can ever direct magnetic waves into a coherent beam like form cheaply and conveniently. Right now wireless power charging radiates much like light from a lightbulb, the amount of energy your device receives drops off exponentially as you move away from the charging coil. And any of that energy that's not charging something is wasted.
If we can, so to speak, target individual devices, and bring the resulting energy transfer up to acceptable levels of efficiency at a good distance then we'll be good. Because if you have to have your device sitting very close to specific spot then there's not really much point in not just plugging it in.
... the marketing department and the vaporware wizard are trying to mess with inverse-square law.
at least until there's a patent on it. *runs, ducks*
Give or take a few details, radio waves and wireless power behave pretty much the same. For a signal source that broadcasts in all directions, the signal strength necessarily will drop proportionally to the square of the distance. The only thing that can prevent this is when the signal is made to be directional, e.g. by broadcasting it from the focal point of a parabola and aiming it at another parabola where it's collected at the focal point again. If you don't make your power signal directional, most of the power is just gonna leak away into the atmosphere.
With regards to using a parabole to make the signal directional... note that a parabolic shape may not necessarily be needed. Since the power signal is an electromagnetic wave, perhaps the power signal can be made directional using the electromagnetic equivalent of a fresnel lens. So I wouldn't be as fast as to discard the possibility straight away.
But accomplishing high efficiency by simply embedding a run-off-the-mill charging pad in a concrete wall? Fat chance.
I think these are a great idea and I would not be surprised if Apple start to support them in the future. A phone could be built with no open connections at all. Just wireless data and inductive charging. But over longer distances the laws of physics catch up with up. Obviously the shorter the wavelength the less doffraction you get over a given distance so if you direct power with a laser and convert it into electricity with a photovoltaic cell then you could easily get more efficiency over a few metres than with induction. Maybe in the future it will be considered normal to transmit power that way.
http://michaelsmith.id.au
...but, the further you go the more it resembles eating your lunch sitting on power lines.
At the one end, there is no measurable danger in charging handset on a pad charger. But do you really want to spend all your television watching hours in a room where 200 watts of power is being beamed to your TV (and 19x being radiated) from the wall to save you the bother of the unsightly cord?
If you have magnetic wave energy, you have electric wave energy, which means you have RF. You can shape the way you transmit RF energy, but there are no perfectly absorbtive receivers, and splatter is a function of distance. So at contact distance (phone on the pad) it's pretty fine.
The claim was "most"of the power gets there. Let's assume they are not full of crap. So 49% of the power is splatterd around. So your 1800 watt cordless hairdryer splashes 1730 watts around the bathroom? And people worry about .1 watt GSM transmitters in their phones?
I guess I need you to trust an A/C on this point, the extra four orders of magnitude makes a difference.
The problem is inefficiency. Power drops with the square of distance. That means you need a bigass transmission source to get a small amount of power any distance away, hence why things like FM stations have 5 digit wattage transmitters.
Yes we have been able to transmit power wirelessly for a long time, no it is NOT practical or efficient. If you are enthralled with Tesla, spend some time reading some actual books on him, not just the silly piece by the Oatmeal. He was a fascinating man and worth your time to learn about, but you need to learn about him if you want to go spouting off.
He didn't invent some magic transmission technology we can't replicate, he invented an inefficient transmission technology that we can replicate, but don't, because he was not able to solve the efficiency problems (and it may not be physically possible to).
They've seen people who live under high voltage power lines seem to have a higher rate of cancer
So I would think it would be possibly dangerous to come close to fields where energy is passing through your body. The more energy involved the worse off I'd think people would be. I don't tend to worry much about low energy fields like cell phones or wifi. Yet if a job powered all the computers with remote energy so I'm exposed all day long, I'd have to decline that job. No sense risking cancer for any amount of money.
God spoke to me
I'm as big a Tesla fan as anyone, but I'm also a practical electrical engineer.
Someone above already raised the end-point billing issue the utilco's will have, so we needn't bother with the bean-counter side of things. MBA's, rest easy. Your obscene profits are safe.
However, going from a theoretical ability to blast x amount of joules across an air gap to capturing a useful fraction of x without frying the adjacent wildlife and neighbors is quite another thing. As TFA points out, they seem impressed with a 10% capture rate, which to an engineer means a 90% loss of efficiency.
There is also this unpleasant fact of biophysics: sufficiently strong electro-magnetic fields, regardless of frequency, are inevitably fatal. The required grounding, shielding, etc. would be so outrageously expensive that the cost of copper wires pales.
Some science fiction does eventually become science fact. However, Thermodynamics, biochemistry, and basic engineering discipline relegate most of it to forever remaining fiction. Sorry, no Nobel Prizes here.
Scruting the inscrutable for over 50 years.
The error in the critics is that they are talking about magnetic/induction.
RF information (and thus power) can travel over E fields as well.
As for focusing the beam - that is called antenna gain. Higher gain antennas have greater focus.
Higher frequency is easier to focus than lower frequency.
In the case of RFID, at 900Mhz, 1 Watt of power, and 6db gain antenna, you can power an RFID tag at 90ft! - a larger 6x6" tag - with a metal back plain.
Yes there is loss - lots of it in fact - but it can work. The more common, 10cent tags are on the order of 20ft (same chip - just efficiency of the receiving antenna).
There are practical limits on how much gain a planer antenna can have.
>Menno Treffers, chairman of the Wireless Power Consortium, says you can broadcast wireless power over six feet, but the charge received will be less than 10% of the source.
He is correct, although you don’t provide any details of his exact statement. If you built a complete sphere around the transmitter you could theoretically get far more than 10% of the source, but he is probably assuming a much smaller antenna 10 feet from the transmitter. Most of the power from the transmitter is not going anywhere near the antenna and therefor can’t be transmitted even if the antenna is 100% efficient.
>WiTricity and 3DVOX, however, are fighting those claims with demonstrations showing their products are capable of resonating the majority of source power.
I don’t think you read the page you linked to very carefully. Where does 3DVOX say anything about “resonating the majority of a source power?” They are just stating they can power some household electronics and make no claims whatever about the efficiency of their system. The Witricity doesn’t make any claims about efficiency either. If you want to buy their “Prodigy” system for a thousand bucks and light up some low-power LEDs a few feet from a transmitter, you go right ahead. Even there promotional page just says you can send power through a “desk top, glass window, (or) a brick wall.” That’s quite easy. Sending it though 10+ feet of space, that’s the hard thing.
In my book, lighting up a few LEDs is exactly the kind of thing I consider a nice "parlor trick."
"...capable of resonating the majority of source power."
Where are the "hyperreality" and "quantum continuity" marketing scam words so popular on other idiotic claims?
Are there no "ethereal vibrations" or "ionized ions" or "magic ponies" in the announcement?
I guess it's time I throw away my EE texts...and, for that matter, Physics texts, eh?
Marconi and Braun, Nobel prize winners. Tesla was like 10 when they did this.
The Kruger Dunning explains most post on
Looked at one of the demo videos. There is a 4000watt transmitter (in middle of floor, nevermind the radiated power someone is gonna trip on it!) a few feet away from most of the stuff and i don't see 2000w worth of stuff.
Don't know how it works, don't care so much to look. I don't plan on adding a 4000watt transmitter to each room, seems like a half dozen power cords would be a bit cheaper. Not that i have any interest or hope for anything called 3D power...sigh.
But...Does the green carpet in the one vid play into it? The TV didn't come on til he touched the floor.
Wonder how good the wireless internet is 18 inches from that transmitter where he set the laptop down.....
What if i add this 4000 watt transmitter to my apartment, as does my neighbor, etc. Before we finish the complex we will enough power running to add a couple TV channels much less the recievers :O
why can't they transmit it with lasers
(mental image of toddler looking into the power transmitter)
never mind
intellectual property law is philosophically incoherent. it is your moral duty to ignore it or sabotage it
There seems to be some confusion on this thread between magnetic resonance, which is the type of power transfer used by WiTricity and others, and radiative RF which is the radio technology we are used to. For example, received power does not fall off with the square of distance in the case of magnetic resonant systems. There are definitely a ton of challenges to this technology, but it is good to keep in mind that they are NOT talking about transmitting a high power RF signal and having it received at range. Here is a link to a paper that describes both types of systems so you can understand the implementation and trade-offs. The author's have achieved 80% efficiency over a few meters using magnetic resonance. Experimental Results with two Wireless Power Transfer Systems http://sensor.cs.washington.edu/pubs/WISP-WARP.pdf Video and other good info: http://www.alansonsample.com/research/wrel.html
The referenced paper actually describes two systems based on RF power transfer. Here is one on magnetic resonance: http://www.alansonsample.com/publications/docs/2010%20-%20TIE%20-%20Magnetically%20Coupled%20Resonators%20for%20Wireless%20Power%20Transfer.pdf
If you want to avoid 1/r^2 effects you need a beam. You won't get that with 60 cycles/sec power; wavelength is too long and a transmitting array will be too unwieldy. Microwaves can be beam-formed. However, if your beam is carrying, say, 1KW of power in a narrow beam, the power density is going to become large. You like to run your microwave oven with the door open? No? Right: the power density could become dangerous. You'd need some way to power your computer, lights, engines, whatnot, with no coupling of that power to flesh. That's tough: we conduct electricity pretty well at most any frequency. Then too these narrow beams need to be aimed at whatever is to be charged. You don't just carry your devices into the house and they magically get power.
If you can do the "get power anywhere" trick, they're not using a directional beam. They won't survive distance power loss either, and you would want to be careful about spending time in the area. If they can do distance, the energy must be concentrated into a beam or narrow area. (It is easier to achieve this with the technical marvels called "wires".) If the beams are sent through free space, caution is advised in crossing such beams. Remember the microwave open-door example again...those devices work by dumping lots of EM energy into a region of space. A power beam would be such a region.
It could get hot to be in such. Might ignite walls too.
Wireless power extension cords.
There are a lot of hard engineering problems to overcome, even if the system was efficient... For example, a second resonant load nearby severely de-tunes the system, antenna mounting considerations are of supreme importance (good luck putting one on a laptop full of metal), and antenna alignment is absolutely crucial! The whole WiTricity concept might be sound in theory, but the engineering challenges are monumental.
Chapter 4 of the ARRL Handbook has a section on coupled resonant circuits. The critical coupling coefficient is equal to the inverse of the geometric mean of the loaded Q's of the two resonant circuits. With the coupling coefficient dropping with the 6th power of the spacing, once the spacing significantly exceeds the radius, the required Q's really quickly become unrealizable.
A Shadeless room is a brighter room.
Anyone interested in wireless power transfer should look into Magnetic Resonance imaging systems. They are doing excatly the same thing ie transferring large amounts of rf energy through air into the patients undergoing examinations. One of the most difficult problems is keeping the patients cool during the imaging. The rf fields cause local induced rf currents in patients and is some cases these result in burns. The fields are generated by antennas similar to the ones they are using for wireless power transfer.
It requires a lot of work to supress the induced rf currents even in the highly controlled environment of a MR imaging system. No external conducting wires are allowed anywhere near the transmitting coils. This includes conducting surgical equipment etc. There is a lot of education for the nurses before they know what can and what cannot be done inside the volume exposed to rf fields. Anyone claiming that the same problems would not appear in home or office environments is lying or does not know what he is talking about. I have seen sparks flying and plastic insulaton of the cable melting when a cable without rf supression devices was used...
I have designed rf coils in MR systems for > 10 years. If there was an easy way of handling these problems I'd heard about it by now. Ask them about the SAR http://en.wikipedia.org/wiki/Specific_absorption_rate for humans close to the wireless transmission coils. Does the system fulfill the SAR limits for general public? Do not accept anything but specific and definite answers to the regulatory questions before even considering to invest into this kind of tech.
I used to have some cool books from Yugoslavia, wish I could find them. As I remember, the big problem was ground conduction, as far as the losses went. The New York shore looked promising. -hoboroadie
No matter what kind of technology is used in the antennas a local RF magnetic field is produced. This will necessarily cause induction currents in any exposed conductors. In MR systems these currents are always supressed by special traps inserted over all electrical conductors in the proximity of the transmission coils. A cable without supression devices can become a focussing device for RF fields and cause high SAR. Why should we accept high SAR from this tech but at the same time be wary of SAR effects from cell phones?
A home equipped with long distance wireless power transfer antennas would need to have supression devices inserted on any and all cables that can be brought near the transmission antennas. This is impossible to guarantee. A mismatching or non-supressed cable could become a fire hazard due to uncontrolled induction heating. I have seen this happening in MR systems.
.....? So how many of Heinlein's novels did you have to read before finally concluding his non-cursing creeps you out? Was it a growing sensation, a feeling of unease slowly building inside you, nibbling away at your very soul as you shifted restlessly on your seat, brow furrowed in discontent? I can just imagine you sitting there with feet kicked back in your overstuffed blue armchair by a cozy fire, suddenly shooting straight to your feet when it dawns on you: "Holy shit! Now I realize what's been bugging me the fuck out about this crazy ass novel! It's been six chapters now and not the first fucking sign of a cussword. I'm starting to think the guy is a goddamn prude, honestly. There sure as hell better really be something lewd or crude in this incestuous intra-family love triangle / murder he's currently setting up, or I just might throw this book across the room......before hurriedly snatching it up and continuing reading to confirm that he did indeed not curse once. By God if I have to suffer through every single one of his bullshit Puritanistic preachings to get my satisfaction I will! And if I don't get it.....? Well I suppose Heinlein is a really fucking creepy guy."
Personally, I think the Tesla worship among geeks has gotten WAY out of hand in recent years. Yeah, I know the Evil Rich Guy Edison vs. the Poor But Plucky Tesla makes for a great literary narrative. And I don't discount the guy's work (particularly with alternating current, which he was right to argue for over DC as a practical means of long range electrical transmission). But he wasn't a god, he wasn't 100 years ahead of his time (as some recent hyperbole would have it), he didn't invent anything which subsequent engineers haven't since replicated and improved on, and he didn't certainly didn't invent EVERYTHING (the list of claimed inventions seems to get longer every year, in spite of the fact that he remains decisively dead).
I think we do him an honor to recognize his REAL work. But we do him a dishonor to exaggerate, or even mystify, his accomplishments.
SJW: Someone who has run out of real oppression, and has to fake it.
WHY was Marconi on Radio revoked & Tesla posthumously awarded as "The Father of Radio" then, hmmm?
* See here -> http://www.tfcbooks.com/articles/tws8a.htm
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PERTINENT QUOTE/EXCERPT:
"In 1943, the year of Tesla's death, a landmark ruling by the U.S. Supreme Court ,b>invalidated the Marconi patent because the fundamental radio circuit had been anticipated by Tesla. It is worthwhile noting the following definition of radio that was developed as a result of this case"
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(Now, be a good boy, & "EAT YOUR WORDS", & tell us - HOW DO THEY TASTE?)
APK
P.S.=> Compared to Nikola Tesla? His "peers" like Marconi & Edison were NUMBSKULLS... & Edison KNEW it if anything (hence, his 'campaign' to SMEAR alternating current & to have Tesla "wiped from the histories"). This was a GIGANTIC BLOW to his "ego"... no questions asked, based simply on noting Edison's "effete retaliation" reaction... apk
Sending out power for wireless charging is inefficent, but the radio and TV stations are already sending out tens of thousands of watts. Also your wifi is already transmitting. Absorbing that energy 24/7 would at least help keep a phone or some low power device charged, so why not.
The magnetic field drops off rapidly with distance. At very close range, south American monkey in treetops near the line during winter range, there is so much induction that there is enough heat to be felt so the monkies kept warm. A field strength that high was the cause of many miscarriages among women that used poorly shielded RF plastic welding machines in the USA in the 1950s-60s. You've got to be almost close enough to worry about arcing to get that much RF from a power line, but there are known problems. Where things get odd is people insisting that twenty metres from a line is a problem, when at that range you'd be getting a tiny percentage of what you'd get from an electric blanket.
These are inductive near-field communication devices. They use a linear transformer (two circuits with self inductances, and a mutual inductance), with capacitors, to transfer power to a load. The capacitors cancel out the self-inductances of the transformer. There is no magic. Greg Durgin of Georgia Tech has a good lecture available on Youtube, that goes over the circuit analysis of such systems : https://www.youtube.com/watch?v=qwEl5Up4AIU&feature=plcp
The range of these systems is quite poor.
A static magnetic field falls off by the cube root of the distance 1/(4pi u_0 d^3)
A static electric field falls off by the square root of the distance 1/(4 pi e_0 d^2)
Flipping (alternating), or directing the field will not change this, its game over for power transfer if you want to put any distance between you and the receiver.
The reason geek bring up tesla worship so much is because your average non geek, not aware of edison real works, but rather of the aura he got, worship edison as if he was the inventor of many many things. The edison worship is much more irrational than the tesla worship.
Billing can occur by the address of the device. And while it will be able to be spoofed, and all forms of security will be developed, it will be no worse than your neighbour 'borrowing' your cable.
It's all relative. It may seem useless to only get 10% efficiency from this power source, but if someone is willing to live with that inefficiency, what's the problem?
Am I the only one who noticed the green mat on the floor?
A Tunable Phased Array should get you a roughly linear beam in an almost arbitrary direction. If you can detect the location of your receiver, you're all set - just keep tracking it as it moves. If you can switch your array quickly, you can even feed multiple receivers by time-slicing.
You could do the same thing with parabolic reflectors, or masers.
Not nearly as efficient as wired power, and not something I'd want pointed at me at high power, but not impossible.
I always use FACTS - & that's what you little trolls can't seem to handle very well (since I use those facts to UTTERLY DISPOSE OF "YOUR KIND", with ease... truth's LIKE that boys - get used to it!).
* However, then again? That's what "your kind" is used to in this life - being "blown away", lol!
APK
P.S.=> All you have now, as per your AC trolling usual? Off-topic b.s. that has nothing to do with the subject @ hand - it's ALWAYS the same, blowing away b.s. artists that spout utter b.s. like you have...
... apk
IF the "best you've got" is going off-topic and doing impersonations of myself (not a first here by ANY means on this forums) OR attempting to "mock me"? You only prove my point more.
* You FAIL, and you know it, I KNOW IT, as does anyone else reading.
APK
P.S.=> The funniest part that backs my last reply to you, and regarding custom hosts files? None of you EVER has disproved a single point of my posts on them... not a one. No, instead? All you have/"the best you've got", is b.s. like what you posted... speaks WORLDS in MY favor vs. you & those like you (trolls)...
... apk
I think it would be amazing if a giant solar panel could be built in space that could wireless transmit power back to the planet.
I'm sure Mitt finds the tale of Nikola's humble unfettering of American Enterprise inspiring.
Back during WWII, some enterprising folks stole power from the near field of a UK radio station. Neat trick -- but they were prosecuted for hurting the war effort. Inductive charging works, but earlier comments regarding inefficiency are spot on. in a warming world, where we actually worry about the cumulative effects of all those chargers plugged into the walls 24/7, let's hope this technology never catches on.
"many people have disproved your points about hosts files with well reasoned, factual arguments." - by Anonymous Coward on Thursday November 01, @12:28PM (#41843299)
Considering you RAN (lol, like the "beyotch" you are) from disproving them here today no less -> http://news.slashdot.org/comments.pl?sid=3222163&cid=41843523
?
(Please... lol!)
* QUESTION: What is it like being a totally cowardly waste of life like yourself?
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"You just chose not to listen and made it into some kind of bizarre crusade" - by Anonymous Coward on Thursday November 01, @12:28PM (#41843299)
Ok, I'm listening - go for it!
Disprove my points on custom hosts files that benefit end-users of them in terms of:
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1.) Better speed-bandwidth & electricity usage they pay for out of pocket
2.) Better "layered-security"/"defense-in-depth"
3.) Better reliability (vs. downed or DNS-"poisoned" redirected DNS servers)
4.) Better speed via hardcodes of favorite sites as hosts file records properly resolved
5.) Better anonymity (to an extent vs. DNS request logs)
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If you keep running from that challenge, just as you did here -> http://news.slashdot.org/comments.pl?sid=3222163&cid=41843523 you're only showing us further that you truly ARE, a cowardly little worm that likes telling lies... nothing more.
(Just how BADLY have I utterly "dusted" you here or elsewhere in computing technical related debate that your "geek angst" is so "up" that you must continue to stalk & harass me as well as impersonate & libel me as well, hmmm?)
APK
P.S.=> I mean that - is your life SO "f'd up" that you "get off" on trolling others online?? Are you really THAT pitiful, ALL THE TIME???
"And I'm not the timecube guy" - by Anonymous Coward on Thursday November 01, @12:28PM (#41843299)
Sure, you stalking freak... bullshit!
You posted about it here in this thread -> http://hardware.slashdot.org/comments.pl?sid=3222519&cid=41842433
AND
You did your MILES LONG b.s. post designed to "mock me" -> http://news.slashdot.org/comments.pl?sid=3222163&cid=41832417
(& others called you a nutjob there for it -> http://news.slashdot.org/comments.pl?sid=3222163&cid=41832445 also - GROW UP, or get professional psychiatric help already...)
"just someone else who finds you intensely obnoxious" - by Anonymous Coward on Thursday November 01, @12:28PM (#41843299)
Oh yes, lol - stalking, harassing, libeling, & trolling others is SO "not obnoxious"... give us a break, freak!
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"and likes winding you up to waste your time" - by Anonymous Coward on Thursday November 01, @12:28PM (#41843299)
Yes, stalking & harassing others is "CONSTRUCTIVE" use of YOUR time!
Please... all you end up doing is wearing egg on your face for your blatant lies, and looking even more foolish running from an honest challenge YOU say you can 'back up'... ok, do it then.
(Good luck - nobody here EVER has disproved my points on hosts files & 100's here agree they're great!)
Seriously - Go get professional psychiatric help already (you freak)...
... apk
At this point though, the volcano powerplant makes more sense.
dude, you forgot the link to your Kickstarter page!
the preceding comment is my own and in no way reflects the opinion of the Joint Chiefs of Staff
Isn't effective data rate directly correlated with power levels?
So yelling at grandpa really does make him understand quicker?
the preceding comment is my own and in no way reflects the opinion of the Joint Chiefs of Staff
Next you're going to try to tell us that Telsa didn't invent the teleporter! [*]!
[*] granted, it was more a remote matter duplicator than a true telporter, but there's ways of dealing with that.
the preceding comment is my own and in no way reflects the opinion of the Joint Chiefs of Staff
They drop off with the CUBE of distance.