Re: [Phys-l] Anti theft Tag

[chuck britton <cvbritton@mac.com>]

The rectangular stuff looks like it was intended to resonate when the 
'stolen' goods passed by a large rf field - setting off an alarm with 
the phase shift??


At 2:05 PM -0500 9/5/10, brian whatcott wrote:
>   Norma brought home a garment, and she noticed an anti-theft tag still
> attached.
> This was a kind that I don't often see -  a plastic tag  two inches
> long, with a
>   trapped wire loop.  it looked rather bulky.
> I cut it open to check the contents. I numbered the pixs 1 to 8
>
>   http://s880.photobucket.com/albums/ac6/betwys/Anti%20Theft%20Tag/
> *http://tinyurl.com/24pfdah*
>
> The operating principle was still not completely obvious after inspection.
> Yes there was a sprung cone ball pin collet to trap the wire at its end pin.
>
> But what are the spring leaves for? There is no mechanical connection.
> I supect they may vibrate when exposed to an AC coil, and allow the
>   pin to be pushed in a little further, allowing the balls to
>   rattle - which permits the pin to withdraw.
> The ferrite rubber may increase the flux density at the collet end.
> It holds the flapper shims when not energized.
> Otherwise, the pin collet holds the pin with surprizing force - ten
>   pounds would not extract the pin.
>
> Brian W
>
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