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Scientific Grandstanding at MIT Answered

witricity at MIT.

Am I missing something here? It's a transformer. This is how my wife sonicare charges.

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The difference is the range - toothbrush chargers are almost in contact, witricity works at a range of >2m. I don't get all the details, but it's not a strict magnetic link. The witricity "resonates" - the power-transfer starts small, and each cycle of the signal pushes the power up in the receiver a little more (like small pushes on a swing), until it's enough to do something useful. As I understand it, the plan is to create a system that charges mobile devices (laptops, phones, mp3 players) just by having them in the right room, not connected to the mains via a knitted mess of cables and chargers.

Oh, and if a normal transformer was operated over that range, it would have to have a strong enough field to drag cutlery across the room.

So it's a resonant LC circuit? Like a Tesla coil? BTW The actual range cited in the abstract is 8r, so that 2 m range requires a 1/2m dia. coil.

It's the too cutesy name that makes it suspect.

I'd like to see you transmit energy over 2 meters at 45% efficiency with a transformer.