AVR-Chat

Make yourself an antenna with a spiral trace on a circuit
board! Resonate it with a capacitor to 125KHz and you
should be in. The more sprirals, you have, the better,
because the resonating cap will be smaller and the coupling
to the tag will be better. At 125KHz, the coupling is
primarily magnetic (like a transformer) rather than
electomagnetic (like a radio). More primary turns should
give you better coupling.

Jim


On Fri, 23 Sep 2005 09:22:53 +1000
 "Ivan Vernot" <ivernot@optushome.com.au> wrote:
> Thanks Zack,
> After seeing your post I checked Digi-Key.
> As far as I can see, they only carry the 'TIRIS' (Texas
> Instruments RFID) 
> stuff.
> It is at 132KHz and uses quite large (~1m) antennae.
> 
> I am after an antenna <100mm long  (65mm round would be
> perfect) for use in 
> a 125KHz proximity card reader (think of an access
> control application)
> 
> BTW: I am in Sydney Australia.
> 
> Thanks for the reply.
> Cheers,
> Ivan
> 
> 
> ----- Original Message ----- 
> From: "Zack Widup" <w9sz@prairienet.org>
> To: <AVR-Chat@yahoogroups.com>
> Sent: Wednesday, September 21, 2005 10:25 PM
> Subject: Re: [AVR-Chat] OT: Where to get Custom Coils
> would
> 
> 
> >
> > Hi Ivan,
> >
> > You didn't say where you are located.  Can you order
> from Digi-Key?  They
> > have a whole assortment of RFID antennas and coils in
> their catalog.
> >
> > Zack
> >
> > On Wed, 21 Sep 2005, Ivan Vernot wrote:
> >
> >> Hello All,
> >> Apologies for off topic post but I'm using an AVR for
> this gadget ;-)
> >>
> >> I  am looking for a supplier that is able to wind an
> open core coil to be 
> >> used in an RFID application.
> >> The coil is used for the antenna of the RFID system
> and is typically a 
> >> few tens of turns in reasonable heavy gauge wire
> (30AWG or so) so that is 
> >> it relatively self supporting.
> >>
> >> Does anyone know of a supplier that can supply such
> coils in <1K qty?
> >>
> >> Kind Regards
> >>
> >> Ivan Vernot
> >>
> >
> >
> >
> >
> >
> > Yahoo! Groups Links
> >
> >
> >
> >
> >
> >
> >
> > 
> 
> 
> 
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