Blog Image

RFID sniffer

About this project

RFID is everywhere. Use the easy to build RFID sniffer to find out if objects are tagged.
The RFID sniffer is a simple analog electronic circuit which can detect the presence of 13.56 MHz RFID tags. These tags are commonly used in all kinds of plastic cards like access badges, bank cards, library cards, loyalty cards and so on. Also many other objects may carry RFID tags without you knowing it. Books, toys, and even clothing might be tagged. Carrying tagged objects with you can reveal your identity or whereabouts to anyone equipped with the appropiate tools to read RFID tags.
The RFID sniffer helps you identify which objects are tagged, and which are not.

RFID sniffer workshops at Mediamatic

RFID sniffer Posted on 2009-03-09 14:44

On March 27 and April 4, Mediamatic will host two RFID sniffer workshops in Amsterdam, where you can build your own RFID sniffer under my guidance.
Cost is €25, including all parts for the RFID sniffer.

Sign up here for March 27th, or here for April 4th.

Capacity is limited to 16 people per session, so sign up soon!

Workshop at CMD Breda

RFID sniffer Posted on 2008-11-10 00:11

On November 14th I will be giving a guest lecture and hands-on workshop to students of the Communication & Multimedia Design department of the Avans Hogeschool in Breda, The Netherlands.
The students will all build a RFID sniffer during the workshop.


RFID sniffer Posted on 2008-08-26 18:11

The circuit board for the RFID sniffer kit has been improved for easier manual soldering
(slightly larger pads and traces) and the battery is now mounted in a hole
in the board to reduce the overall height.

Blog Image
Included in the kit is a soft plastic sleeve with ziplock and a lanyard with clip for carrying the RFID sniffer around your neck.

The improved RFID sniffer kit can now be ordered at for €15 (world-wide shipping included).

Blog Image
A fully assembled version is also available for €40 (world-wide shipping included). The assembled version will use the first generation circuit board until stocks are exhausted.

Both versions will be in stock after September 10, 2008.


RFID sniffer Posted on 2008-07-08 11:26

Make your own RFID sniffer using my new RFID sniffer kit. It contains a professional quality circuit board and all components, including a battery. Just add solder!

Blog Image
The kit can be ordered for € 10 (plus shipping) by sending an email to marc at marcboon dot com. Specify the delivery address and I will send instructions for payment and the cost of shipping.

On July 17th 2008 I will host a hands-on soldering workshop at V2 in Rotterdam where you can build your own RFID sniffer on the spot. For more information go to or This workshop is free (except for materials) and open for everyone.

Tagged, or not?

RFID sniffer Posted on 2007-11-12 12:56

tagged cards
Some of these cards are tagged with RFID chips, some are not. Do you know which?

tagged keyring
This RFID tag was used during Picnic ’07 to activate some interesting
installations using RFID in the context of a social network. Innocent,
or not?


RFID sniffer Posted on 2007-11-11 18:18

I assembled the first prototype of the RFID sniffer on one of the printed circuit boards. Soldering the small SMD parts requires a good soldering iron with a fine tip, a pair of tweezers and a steady hand. I first tinned all solder pads and removed excess tin with the help of solder wick. This makes soldering the parts much easier.
Then I placed the SMD parts one by one, holding them with the tweezers and heating one of the solder pads to fix it in place. Then applying a little bit of solder to each of the other pads. Again using solder wick to remove excess solder if needed.
The trimmer and potentiometer were the hardest parts so solder, due to the small contact surfaces on these tiny components.

Blog Image
After connecting the battery, I pressed the switch and the LED came on. I just had to adjust the level of the potentiometer to set the threshold to light the LED only when a RFID tag is near the loop antenna.
Measuring the frequency with an oscilloscope revealed that the frequency was about 16 MHz, quite a bit higher than 13.56 MHz, but it could still detect tags. I adjusted the trimmer capacitor anyway, to set the frequency to approximately 13.56 MHz.
The full range appeared to be from 12.7 to 16.2 MHz, but it hardly affects the detection of tags. I can probably get rid of the trimmer and use slightly higher values for capacitors C1 and C2 to fix the frequency to within a few percent of 13.56 MHz.

The oscillator frequency can be measured without having a oscilloscope probe making contact with the circuit. You can construct a coil from a few turns of solid copper wire and hook it up between the tip of the probe and its ground clip, and then holding it close to the loop antenna. This will pickup the emitted RF signal just like a tag would do.

PCB etching

RFID sniffer Posted on 2007-11-10 13:23

I fabricated a few printed circuit boards using the photographic method. I sent my layout in pdf format to a printer, and had it transfered to film with a photoplotter. This gives a mask with high contrast and resolution. You could also try to use a laser printer to print on transparency sheets, such as used by overhead projectors, but the resolution and contrast of these prints are not as good.
Then I used a UV light box to expose a piece of photosensitive printed circuit board with the mask. The board is composed of a fiberglass-reinforced epoxy base (FR-4) with a thin layer of copper on top, coated with a photoresist which, when exposed to UV light for a few minutes, will dissolve in a solution of caustic soda.
The opaque black pattern of the layout masks the photoresist in the places where the copper should remain. The exposed part of the photoresist is dissolved, and will expose the bare copper surface. The board is rinsed with water, and then placed in a solution of ferric chloride. This will etch away the exposed copper, but the pattern covered with the unexposed photoresist is protected from the etching liquid and remains untouched.

RFID sniffer etching
When all copper is etched away, the remaining photoresist is removed with acetone. The result is a well-defined pattern of copper, forming the traces and pads of the electronic circuit, including the loop antenna.

RFID sniffer board


RFID sniffer Posted on 2007-11-03 04:02

I entered my revised schematic into the freeware Eagle layout editor. I had the bright idea to put the whole circuit, including loop antenna and battery, on a circuit board the size of a standard ISO 7810 card. This way, the RFID sniffer has exactly the same size as the cards to sniff…

RFID sniffer schematic
The circuit is powered by a 3V lithium coin cell. These are small and flat enough to be included on the card. I also added a small push button switch, so the circuit is only powered while the switch is pressed. This will guarantee long battery life, since it can’t be left powered on by accident.

The first design of the single-sided layout fits nicely in a corner of the card, leaving enough room for a square loop antenna and the battery. Since the layout is single sided, the circuit board can easily be fabricated on the kitchen table, or even silk screened with conductive ink! All parts are surface mounted, so there are no holes to drill. The underside is totally flat and free of electrical circuits.

RFID sniffer layout
Total parts cost (excluding board, including battery) is about 5 euros.

« PreviousNext »