The 'rub'
Want to detect the presence of RFID readers? Want to control when a RFID tag is active or readable? We describe how to do both using bits of copper and card, and some readily available electronics hardware.

Longer preamble
Radio frequency identification ( RFID) is rapidly growing in popularity. RFID tags are found everywhere. They're attached to container freight, in those funny-looking white labels you find in newly purchased books, embedded in many corporate ID cards and passports, etc. The tags have a few common properties: they transmit a unique ID number, are optimized to be 'read' from predefined distances, and are usually small so they can remain unobtrusive or hidden.

RFID readers are used to track nearby tags by wirelessly reading a tag's unique ID (see Figure 4); a tag simply has to be brought into physical proximity with a reader to be read. Readers are mostly used for industrial or commercial purposes, e.g. asset tracking or electronic payment. Wal-mart use RFID tags and readers in their supply chain. The technology is also used in mass transit systems in cities like London and Hong Kong. In Japan, many mobile phones incorporate readers to enable e-money payments in shops and vending machines.

For those of us who want to experiment with RFID, the problem is that the technology is almost always black boxed. That is, the inner workings of a tag and its interaction with a reader is hidden from view, and thus difficult to have much control over.

In the two exercises that follow (building a RFID reader detector and a tilt-sensitive RFID tag), we offer an example of how you can start revealing some of the workings of RFID and thus gain some control over the technology. The two exercises also hopefully show that the technology is relatively simple and how it can be extended to support some interesting interactions. We offer some other possibilities that build on our examples at the end.

Step 1: Material and Tools

This section provides an overview of the necessary materials and tools.

Materials (see Figure 1):
We need the following material to built the basic RFID reader detector.
- Cardboard (around 100x70 mm)
- Conductive copper tape (e.g., order number 1218478 at www.farnell.com)
- Capacitor 82 pF (picofarad) (e.g., order number 1138852 at www.farnell.com)
- Low current LED (light-emitting diode) (e.g., order number 1003207at www.farnell.com)

Tools (see Figure 2 and 3):
- Craft knife and scissors
- Insulating tape (e.g., order number 1373979 at www.farnell.com)
- Soldering iron and solder

RFID reader for testing (see Figure 4):
To test our RFID tags we need an RFID reader that can operate at a frequency of 13.56 MHz.
There many readers for this widely used RFID standard, for instance the Sonmicro MIFARE USB reader (http://www.sonmicro.com/).
Note: The Phidget RFID reader does not work with the tags created in this project, as it uses a different frequency for communication with the tags (125 kHz).

Advanced material (see Figure 5):
The following material is necessary to build the second part of the project: the tilt-sensitive RFID tag.
- Micro tilt switches (e.g., www.digikey.com)
- RFID ICs (e.g., MIFARE Standard 1k, part no. 568-2219-1-ND at www.digikey.com)
<p>Very Interesting!</p>
<p>Can we make a custom RFID tag? or even a dynamic tag in which we could enter the unique ID ourself for testing purpose? </p>
<p>Is there any way we can use a custom number in the RFID chip? Like, if I want to clone my office card into this? or will I have to go through some other methods? </p>
<p>Made the reader part. The LED glows very softly, but it works!</p>
<p>Interesting work </p>
<p>nice project thanks.</p><p>How forgiving are these antennae with resonant frequencies. Can the size be adjusted without much adverse effect or do you have to recalucate turns dependent on air core size etc? I would like to make an antenae that is about 2cm by 2cm. would that seem doable.</p>
<p>Great project. Thank you for documenting and posting it. I would like to make one and have a few questions for anyone who might know....</p><p>1. Does it matter how the LED is oriented when attached to the antenna (anode/cathode)?</p><p>2. Do you know of any common stores that use 13.56MHz RFID readers where it would be easy to test without needing to purchase a reader?</p><p>3. Can the NFC in a cell phone (mine is a Galaxy S4) be used to test as a reader? Is it strong enough?</p><p>4. Does anyone have plans for a 125KHz version?</p><p>5. If you don't have an 82pF cap, can you group a couple 333s with a few 103s and be 'close enough'?</p><p>6. How important is the spacing between the copper strips?</p><p>Any help is appreciated. Thanks!</p>
<p>are you a pet stealer?</p>
<p>why do you want to disable RFID tag? to steal something not yours?</p>
<p>what is the process of data transmission from tag to reader.</p><p>is there any boud rate consideratiion?? </p>
<p>How do you determine the loops?</p>
<p>How do you calculate the windings for the flat planar coils?</p>
<p>I am new to RFID technology, but really enjoyed this! It is finally making some sense to me. I am going to try to do this project on my own, but one of the materials you listed does not seem to be still at the same product number as before. As I said, I am new to this and don't know the difference between the other products available when I search for similar ones. Could you provide a link that would replace or is the same product as this material:</p><p>Capacitor 82 pF (picofarad) (e.g., order number 1138852 at www.farnell.com)</p><p>Thanks!</p>
hi. I am new to electronics. I have some basic knowledge of some things work but nothing about radio frequencys. would this light up or react to a cell phones rf? or something such as WiFi? I'm trying to make something that will light up or react when my cellphone goes off or I receive a text.
Thanks for this great post! Can't wait to do it myself on my next weekend project.
This is a nice tutorial but it would also be interessting to see how you connect your antenna to the mifare RFID Chip. Is there also a tutorial for? Thanks!
Hello, <br> <br>I want to make UHF tag with 865 to 868 MHz . what you should i have to change in above material to make RFID tag?
Hi, <br> <br>Nice RFID instructable! I have a project in mind for an RFID reader, I have a specific requirement for the antenna's placement and wondered what I need to take into consideration. What materials are suitable power requirements number of loops etc etc. Are you able to help me? <br> <br>Thanks
You should change &quot;stripes&quot; to &quot;strips&quot;... otherwise, a very nice instructible.
&quot;Instructable&quot; <br>
Who cares.
I am new to electronics and RFID, but how does the LED get the power to light up? Thanks for the great post!
Magic.<br> <br> In this particular instance, it takes the form of a series of ripples in the fabric of the universe that can propagate across space. This form of magic is commonly referred to as an 'electromagnetic field'. The RFID reader creates an electromagnetic field nearby it that induces (induction is the process through which a changing electromagnetic field creates voltage across metal objects) a voltage (a term used to refer to the total difference in the amount of positive and negative magical energy between points) along the length of the antenna. The LED then allows the positive and negative magical energies on either side of it to pass through it,&nbsp;annihilating&nbsp;each other in the middle, and creating another type of magical ripple (commonly called electromagnetic radiation) that you observe as light..<br> <br> That is also the same reason that metal sparks when you put it in the microwave (I have personal experience doing this...), because the microwaves induce a (pretty high) voltage across the metal, enough to make sparks jump.
Wow! Thanks! <br> <br>-Doctordv
I used some of the information here to successfully design and create a RFID Reader Detector that operates at a very low standard frequency, 125 kHz. SparkFun and others sell devices that operate at 125 kHz. <br>Because of this much lower frequency, my antenna coil and capacitor have much large values that the device described here. My Instructable also includes the math that underlies the selection of coil and capacitor sizes. You can find more about this if you can successfully go to <br>http://www.instructables.com/id/RFID-Reader-Detector-Easy-to-Build/. <br>Also, it is important to remember that a RFID Reader is a completely different device than a RFID Reader DECTECTOR. My device merely lights up if it is close enough to a Reader that is using/emitting a 125 kHz signal...
This is a fascinating project. I've been looking for a way to build a (very) cheap RFID reader, and I was wondering, have you tested this as an aerial for a reader? <br>
i would like to know about the RFID reader if it is universal.. <br>or it can read any tag... <br> <br>this is so nice...it really helps... <br> <br>thank you..
do you know how to make an rfid &quot;reader&quot;?
Can you make the antenna as big as anyone would want it to be? For example: half a metre? I am making an gramophone-like player for kids. Where they can place cubes that represent different tones on the &quot;installation&quot;. But all RFID antenna's that are for sale are to small for the radius. <br> <br>
You should enter this in the kit challenge. <br>-Doctordv
Please tell me why the tilt switches are required?

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