Jinx,
        It's in your own back yard!!!!!! No kidding.... Microchip calls it
RFID and manufactures a chip to do just that and more. Check the Microchip
web site, there is more info there than you may won't..

Good Luck

Gordon Varney

> My nephew got a Star Wars thingy for Christmas which is activated
> by a small transmitter key being brought close to it. I'm pretty sure
> it's the type of thing used for ID chips eg put under the skin of race
> horses and other valuable property. My understanding is that the
> main unit or wand supplies enough radiated power to the key to
> enable it to in turn transmit although over a very short distance (1 or
> 2cm). The key has a clear case and the PCB is visible. There's a
> small (4mm) encapsulated chip and a couple of SMT caps, all
> surrounded by a spiral trace that must be the key's aerial. I'd like to
> find out more about this technology. But what's it called ?
>
> Jinx