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Graham Stabler
03-13-2012, 03:58 PM
Hi all,

I have lost a library book and have looked "everywhere" including the last place I would look and I checked the first place I looked twice.

I'd like to find it, to avoid a fee and to read it (The C programming language by Kernighan and Ritchie).

It has an RFID tag, what are my chances of creating some sort of simple tracker? It must be in my house or the family home, I would have thought that I could get a device within a metre of its location. Not expecting the device to know what book it is of course just detect RFID devices.

Low tech solutions prefered.

Graham

Bobb Fwed
03-13-2012, 04:38 PM
I use the Parallax RFID on a daily basis, and my experience is that it won't work beyond a few cm (maybe up to 15). Other RFIDs use very different protocols (different frequencies and other specs), some common ones might work up to 30 to 60cm away. Though, I've heard tales of spec-built RFIDs that work at further distances.
The problem with getting a meter of range, is both the RFID reader/detector and the RFID chip itself must be able to handle the distance.

Also, because there are different frequencies you'd have to know what band the chip uses, and get a reader to match that.

Edit: changed over to metric...the correct measuring system.

blittled
03-13-2012, 04:42 PM
Since the book uses a passive RFID label I believe your range at best would be 8-10 cm. To get a range over that requires an active RFID label. This is just off the top of my head but I know that you have to be very close to the RFID label with the type of RFID reader Parallax sells.

Edit: Bob beat me to the post!

Duane Degn
03-13-2012, 04:50 PM
Low tech solutions prefered.


Sorry Graham, I don't have anything useful to add about RFID. I did notice there are a lot of used copies of K&R for sell at Amazon (http://www.amazon.com/gp/offer-listing/0131103628/ref=dp_olp_used?ie=UTF8&condition=used). $25 for "Very Good", and there was one "Like New" for $35. Buying a replacement is probabably cheaper than building a RFID circuit (but not nearly as much fun).

You've probably already thought of this though. Good luck with the book finding.

Have you seen SparkFun's video about RFID? It's embedded in this page (http://www.sparkfun.com/products/8628).

Graham Stabler
03-15-2012, 02:03 PM
I'm actually wondering if it is RFID at all, the library uses the tags for security and you walk through sensors on the way out.

Graham

RS_Jim
03-15-2012, 03:19 PM
Graham,
Most of those security devices are magnetic. It seems to me you could use a compass module as a magnometer. Not sure of the range but might be greater than rfid.
Jim

johnfos
03-15-2012, 03:28 PM
Have you tried asking the library staff? I bet you're not the first to have had this problem, so if there's a solution they'll probably know about it.

Graham Stabler
03-16-2012, 03:18 PM
Well I did talk to the library and it is much much worse than just losing a book. It turns out I returned it before Christmas!!!!!

Well at least I didn't start a thread asking people to help me make a book tracker!

DOH!

p.s. I bought my own copy a few days ago :)

Duane Degn
03-16-2012, 06:17 PM
Well I did talk to the library and it is much much worse than just losing a book. It turns out I returned it before Christmas!!!!!

Well at least I didn't start a thread asking people to help me make a book tracker!


Oh, but you gave comfort to the rest of us who are starting to have senior moments. I had something like this happen to me not long ago. I can't recall what it was now.

Oh, I remember, I was sure I lost my nice set of needle nose pliers while helping a bunch of cub scouts breadboard a LED circuit (this was several months ago). I found the pliers in a drawer yesterday along with the neatly trimmed wire I had planned to bring with me. The pliers hadn't ever left the house (nor had the wire I had cut for the occation).

Toby Seckshund
03-17-2012, 12:06 PM
It was 50/50 whether you found the book, or the council shut down the library first!