Wireless Power Demonstrated

Necroloth and other readers sent in the story of Witricity's latest demo at the TED Global conference in Oxford, UK. The company is developing a system that can deliver power to devices without the need for wires. The idea is not new — electrical pioneers Thomas Edison and Nicola Tesla assumed that power would be delivered wirelessly. The BBC quotes the inventor behind Witricity's tech as saying that Tesla and Edison "...couldn't imagine dragging this vast infrastructure of metallic wires across every continent." eWeek Europe notes some hurdles the technology must overcome: "The 2007 experiment it is based on had an efficiency of only around 45 percent, but [Witricity's CEO] promised power delivered wirelessly would start out 15 percent more expensive than wires, and improve on that." Intel has also demonstrated wireless charging.

Standard interface?

[elwinc]

Resonant transfer is great stuff, but what we need even more is a standard interface so that all our rechargable devices can recharge at the same source.

Thomas Edison ???

[nurb432]

Electrical pioneer my ass, he just got lucky once and was able to afford to hire good talent ( like Nikola ). But i totally agree that Tesla proved it was possible ( and WAS a pioneer ). But he also proved that it takes more then tech to make such a project work, it also needs funding. As brilliant as he was, a businessman he wasn't, and we were set decades behind on projects such as this.

Retarded.

[girlintraining]

Blasting large amounts of EMI solely to avoid the need to put a battery in something is stupid. Right now EM radiation is controlled to the lowest levels it can practically be in order to achieve some transfer of information between two or more points. Any power transfer system is going to muck up what's already in the air. It's called Shannon's Law -- and no matter how you sex up the technology, the fact is you're raising the noise floor doing this.

Bad engineer. No cookie for you.

Re:Retarded.

[n3umh]

It's called Shannon's Law -- and no matter how you sex up the technology, the fact is you're raising the noise floor doing this.

Bad engineer. No cookie for you.

Except that energy transfer is not information transfer, and doesn't really require any bandwidth. Of course, every emission has *some* bandwidth due to noise, etc, but you should be able to do wireless power with very narrow band oscillators and I suspect you have confine emissions to the the ISM (industrial, scientific, and medical) bands. Maybe it needs a little bit of slow digital transmission if you need to sync devices and chargers beyond just whether or not there is another resonant device around (you don't want charging stations trying to feed power to each other).

But the fact of the matter is that resonant power transfer requires sharply resonant circuits, so you can't emit much power over a wide bandwidth even if something goes wrong.

Re:Thomas Edison ???

[kliklik]

...and by the way - it was Marconi that invented most of what was later attributed to Tesla... and returned to Marconi only recently by world courts.

Actually, it's the other way around. Check [wikipedia.org] your [tfcbooks.com] facts [wikipedia.org].

Re:Thomas Edison ???

[Corporate Troll]

Except perhaps that Stallman was pretty much always right in predicting abuses of software licenses..... The man may be difficult to cope with, but he most certainly is a visionary. That's where the analogy with Tesla is quite fitting.

Re:Standard interface?

[dgatwood]

I think that's massive overkill. Just provide a 12V rail, a 5V rail, and a ground using a polarized plug. Heck, you can probably dispense with the 12V rail. A 5V rail by itself should cover the vast majority of portable electronics these days. Amperage negotiation? Build the supply so that if it is under too much load, it sheds power connections, then periodically switches which jacks are shed. That's much cheaper to design, and it doesn't unnecessarily add to the complexity of the devices that use it.

Re:Standard interface?

[vivian]

DC to DC regulators are very cheap, for low power needs - which is what you are talking about for most small devices that use wall warts.

Here's a bunch of devices, with datasheets & prices.
ahref=http://www.semiconductorstore.com/pages/asp/category.asp?id=56rel=url2html-27418 [slashdot.org]http://www.semiconductorstore.com/pages/asp/category.asp?id=56>
They start at about $1 and go all the way up to 3.86 for a device that can do dual power rails of exactly that spec - 5v to 3.3v.

Of course, if you don't care quite as much about efficiency, or you are only stepping down your voltage a little, you can always use an LM78xx (where xx is the output voltage needed) they cost a buck or two also, and with very few additional components needed.