possible to get electricity without wires?

dpopiz

Diamond Member
Jan 28, 2001
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are there any feasible ways to "transmit" energy that can be converted to electricity to power wireless devices so that they can run completely wirelessly, even without a power cable? 2 things that come to mind are the tesla effect, and the technology behind inductive battery chargers.
 

RossGr

Diamond Member
Jan 11, 2000
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Yes, trouble is that is is simply not cost effective. Low efficency and the real killer no way to moniter use. There was a thread on this several months back.
 

Shalmanese

Platinum Member
Sep 29, 2000
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Yes, you can do fairly high powered, long distance beaming using microwaves. I believe that they managed to get a decent amound of electricity across ~1km without horribly unacceptable losses.

Its still more a toy than any serious application though.
 

f95toli

Golden Member
Nov 21, 2002
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Microwaves can not be used for mobile devices, you need a real "beam" of microwaves and anyone who gets in the way will get fried. Not a good idea.

 

Smilin

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Mar 4, 2002
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I saw this thing once where they were basically using a pilotless aircraft to hover over an area (for recon, or something weather related or some military crap..can't remember). Anyway it was nearly a glider but did have an electric motor on board to run a prop. They kept the thing in orbit for hours beaming up microwave energy.

I also saw this stun gun these people were working on that didn't use wires. It basically fired a laser or some sort of beam that would ionize the air in a straight path to the target. Then a moment later it would discharge and reach the target through thin air-no wires.

I swear I'm not pulling this stuff out ma butt...if anyone seen anything on either of these, lemme know I'd like to read more about them.

Didn't Nikoli Telsa experiment with transmitting electricity through one of the upper layers of the atmosphere? I think they coined the term mad scientist just for him.

 

syberscott

Senior member
Feb 20, 2003
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You can build yourself a small radio and have it run without power if you have a long enough antenna.
 

pm

Elite Member Mobile Devices
Jan 25, 2000
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Thermocouple. Use the temperature differential between two surfaces
Photovoltaic. Uses light to generate electricity
Piezoelectric. Uses vibrations to generate electricity. For example, sound, or the vibrations of traffic.
 

DannyBoy

Diamond Member
Nov 27, 2002
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www.danj.me
Originally posted by: f95toli
Microwaves can not be used for mobile devices, you need a real "beam" of microwaves and anyone who gets in the way will get fried. Not a good idea.

Thats exactly what I was thinking regarding people getting fried.

 

everman

Lifer
Nov 5, 2002
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I remember seeing something a while ago where a company made this mat which plugged in, and you would be able to put things on it like a laptop, cell phone, whatever and it would receive power through the mat. I guess the devices would need to be made for this or some attachment, I don't remember too clearly now. But basically you put things on the mat and it would power them, no wires needed. At least it sounds safer than beaming high powered microwaves :)
 

Mingon

Diamond Member
Apr 2, 2000
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The FBI have a device which can power anything from 1000metres away its torch shaped and microwave iirc.
 

RyanM

Platinum Member
Feb 12, 2001
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Originally posted by: everman
I remember seeing something a while ago where a company made this mat which plugged in, and you would be able to put things on it like a laptop, cell phone, whatever and it would receive power through the mat. I guess the devices would need to be made for this or some attachment, I don't remember too clearly now. But basically you put things on the mat and it would power them, no wires needed. At least it sounds safer than beaming high powered microwaves :)

That technology is the future of electronic devices, I shat you not.

Seriously.

Imagine having your desk plugged into the wall, and everything you set on it recieved a charge - Your cell phone, your PDA, your monitor, your computer. Everything. Entertainment systems would plug into walls and power every device sitting on them.

I think this technology, combined with further enhanced Wi-Fi, will change the world of everyone using electronics, and anyone who doesn't think so is extremely shortsighted. All you have to do is look at the writing on the wall and follow it to its logical conclusion.
 

Shalmanese

Platinum Member
Sep 29, 2000
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Thats the inductive charger technology referred to in the first post. I dont know how well it scales with current though, it might be impractical to run your stereo off it. Its more for things that need to be moved around and on abttery a lot, not for fixed items. There is still a non-negligible loss associated so people will still wire things where possible.
 

rimshaker

Senior member
Dec 7, 2001
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Electricity = movement of electrons

There's electrons all around us in the air but how are you supposed to control their movements?

Besides that, how are you supposed to create the 'free' electrons to conduct in a wireless fashion?
 

dpopiz

Diamond Member
Jan 28, 2001
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yeah I thought an inductive charger style thing would be the best. here's my idea: make a standard for "trasnsparent power delivery" -- it would be an intelligent system that would work sort of like wireless stuff. you would have several of these inductive chargers integratred into all kinds of devices like keyboards, laptops, wireless routers, etc and whenever you bring a device that needs to be charged close to any one of the chargers, it would start charging. if you had enough of these chargers spread out around, you'd get the impression that the battery-powered device never needs to be charged hence "transparent". I think one particularly good application would be a wireless mouse with an inductive charger in the side of the keyboard. during normal operation, the mouse would quite often end up close enough to the keyboard to be charged. then you'd never have to worry about charging the mouse manually or changing the betteries.
 

Lanik

Senior member
Oct 9, 1999
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The Exxon Speedpass and EZTag tollway tags are examples of powered, non-wired devices. They are powered by a radio signal sent by an interrogating device. When the unit receives a signal, it responds back sending a unique ID (RFID). Then the interrogating device takes the ID number and does something with it (like charging an account, etc).

So, we're already using devices like these. Their very low power usage and the technology is not there yet for more power hungry devices.
 

Smilin

Diamond Member
Mar 4, 2002
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Originally posted by: everman
I remember seeing something a while ago where a company made this mat which plugged in, and you would be able to put things on it like a laptop, cell phone, whatever and it would receive power through the mat. I guess the devices would need to be made for this or some attachment, I don't remember too clearly now. But basically you put things on the mat and it would power them, no wires needed. At least it sounds safer than beaming high powered microwaves :)

Yeah I saw that. The mat actually has a bunch of metal nodes on it to transmit the power - nothing real nifty there. The cleverness came in when the mat and the device on top of it figured out which nodes to let electricity pass through. The trick was to let someone have their laptop on the mat that gets power while not electrocuting someone if they put their hand on it or spilled some coffee. It was cool though...they should pump data throught the mat too.
 

Shalmanese

Platinum Member
Sep 29, 2000
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AFAIK, inductive chargers still suffer from the good ole inverse square law which has been what made wireless power so impractical. Move something twice as far away and you get 1/4th the efficiency.

The reason why inductive chargers work so well is because there is only a few mm gap between the charger and the target and because the target is so large relative to the charger. something like a mouse and a keyboard might work but something like a laptop in a house would definately not work via inductive charging. but seeing as wired mouse are perfectly adequate right now, I dont see much point in having an inductively charged on, perhaps a mousemat charger might catch on though.
 

f95toli

Golden Member
Nov 21, 2002
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Originally posted by: Lanik
Their very low power usage and the technology is not there yet for more power hungry devices.

And the technology will never exist for power hungry devices. The problem is that you want to transfer energy, you could in principle put a powerfull radiotransmitter in you room and let it power you laptop but the problem is that the energy in the radiation would heat everything else in the room (including you), there is no way to make the transfer "selective" enough (tranfer energy only from transmitter->reciever) for it to be safe.
 

grant2

Golden Member
May 23, 2001
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Originally posted by: Shalmanese
AFAIK, inductive chargers still suffer from the good ole inverse square law which has been what made wireless power so impractical. Move something twice as far away and you get 1/4th the efficiency.

the tesla article linked above promises 90-94% efficiency, transmitted all the way across the world.

Apparently Tesla figured/proved that transmission in the upper atmosphere was much more efficient than copper wire.

I guess it's probably never going to come, at least not soon... but damn that would be great for the planet if electricity could be safely transmitted wirelessly.

 

RyanM

Platinum Member
Feb 12, 2001
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Originally posted by: Shalmanese
AFAIK, inductive chargers still suffer from the good ole inverse square law which has been what made wireless power so impractical. Move something twice as far away and you get 1/4th the efficiency.

The reason why inductive chargers work so well is because there is only a few mm gap between the charger and the target and because the target is so large relative to the charger. something like a mouse and a keyboard might work but something like a laptop in a house would definately not work via inductive charging. but seeing as wired mouse are perfectly adequate right now, I dont see much point in having an inductively charged on, perhaps a mousemat charger might catch on though.

That's incorrect. The company which is developing the charging pads are targeting them towards cellphones, PDAs, and yes, LAPTOP computers. Full-fledged ones.

Understand this isn't a "few mm" gap - The electrodes on the notebook would be flush with the bottom surface, and would be a few hundred atoms away from the pad when resting on top.

Personally, I see no reason why this can't be expanded to other devices in the next few years. How big do you think a stereo reciever will be in 2008? By that time, I see stereos existing on a single chip or three, with the majority of area being consumed by the PCB to feed the inputs and outputs. How much power would a stereo the size of a paper ream consume?

As for devices that will always be higher consumption, such as monitors and TVs - There's always the ability to put multiple leads instead of one set. The entire bottom can be decked out with them.

To write this technology off without seriously considering the exponential increase in the complexity of technology is, as previously stated, shortsighted.
 

Mday

Lifer
Oct 14, 1999
18,647
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induction chargers are the most commonly used form of charging wirelessly. piezoelectric is used too, but it's not really wireless. the boot-heel charger developed for the military uses this. um, photoelectric is wireless too, but so inefficient.
 

Mday

Lifer
Oct 14, 1999
18,647
1
81
induction chargers are the most commonly used form of charging wirelessly. piezoelectric is used too, but it's not really wireless. the boot-heel charger developed for the military uses this. um, photoelectric is wireless too, but so inefficient.
 

Shalmanese

Platinum Member
Sep 29, 2000
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Yes, but that would still mean you have to put the charger within a few mm of the device. Yes, you can charge laptops on them put you have to place them on a PAD. I said that your not likely to see a laptop being charged anywhere within the house using this technology because it gets impractical after a few cm.

I still think that TV's and the like as they exist now would not benifit from inductive charging, they are heavy and never move around so why bother. However, I can envision really cool "smart windows" which are basically something like a semi-adhesive polymer which you could stick onto a wall and it would recieve both power and signal via an inductive charging device. You could stick one anywhere and get a "window".