RFID Tag Detector

[Eric Simon]

Hi all, I am new to the forum and was wondering if someone could provide me with some assistance on a project I am working on.

I am trying to create a small device that will detect passive RFID chips at a distance of about 12 inches away. I have no need to read the data on the chip, I simply want to detect its presence and have a light flash indicating that a chip was found.

I purchased one of these to get me started. http://www.ebay.com/itm/ws/eBayISAPI.dll?ViewItem&item=141668399650&rmvSB=true

I was hoping that there would be a simple polarity change in one of the pins when the chip was brought close by, but no such luck.

Can anyone help guide me in the right direction?

Thanks,
Eric

 

[AnalogKid]

12 inches is an enormous distance for an RFID tag. While shoplifting tags can be detected at this distance, they work on a different principle.

Separate from that, I think you need to read up on how passive RFID works. It is a broadcast-powered electric field modifier, and since anything metallic can modify an electric field, detection relies on being able to interact with the tag and read its response.

ak

 

[Eric Simon]

Ya, that is what I was getting from my research. I was hoping that this would be something more simpler as detecting instead of reading. I am really trying to figure out a way to place passive tags on objects and be able to have a detector pick them up at about 12 inches. RFID seemed like the way to go at the onset.

Thanks for the quick response.

 

[Colin Mitchell]

The distance depends on the power of the transmitter.

Elektor had an article on this.