or a simple metal detector using nand gate, but you's hand have to ware
something. its more immune compare to unltra sound.

On Feb 17, 2008 10:27 PM, cllow2020 <cllow2020@gmail.com> wrote:

> a ultra sound transcerver with PIC should do the job. simple school
> project
>
> On Feb 17, 2008 2:57 PM, Cedric Chang <cc@nope9.com> wrote:
>
> > What would be lowest cost method of detecting
> > a hand moving through a volume of space.
> > Imagine a media center and you wave your hand
> > in front of it to turn on illumination for all the buttons
> > and knobs.  Interrupting a beam won't work since
> > I don't want anything to extend beyond the amplifiers,
> > cable box and stuff.  Room may be in nearly complete
> > darkness.  Hand waving must occur within 6 inches of
> > target.
> >
> >
> > Cedric
> >
> > --
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>
> --
>
> Best Regards
> -----------------------
>     cllow




-- 

Best Regards
-----------------------
    cllow
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