The first device I saw that had wireless charging was my Sonicare tooth brush, slow but it works.......
Hi Greg,
That is an example of an "inductive" charger, which is very similar to how a transformer works. Two induction coils
(one at the 'transmitter', one in the receiving device) in close proximity inductively couple with each other and essentially form a transformer.
To get more distance between transmitter and receiving device, resonant inductive coupling techniques are being used. This is where the receiver's coil it 'tuned' to resonate a particular frequency that the transmitter coil outputs - much like how an opera singer hits a note with her voice to break glass (she hits the resonant freq. of the glass).
The main disadvantage of these technologies is that the efficiency exponentially decreases as the distance increases (that inverse square law).
Very cool stuff - but at higher power, one has to look into safety issues with the electromagnetic field exposure.
Vinnie
