Picture of Magnetic stripe card spoofer
This instructable demonstrates how to use an electromagnet, a simple amplifier circuit, and a personal music player to induce signals into a magnetic stripe card reader, causing it to think that you have swiped a card through it.

This instructable assumes that you have basic knowledge of electronics and a cursory understanding of C++.

NOTE: This device is useless unless you already know the contents of a particular magnetic stripe card that you want to emulate. Thus, you can't use this device to do Something You're Not Supposed To Do unless you've already done something naughty to obtain the data from a magnetic stripe card you're not supposed to have.

Don't do naughty things. Your mother wouldn't like it.
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Step 1: How it works

Before going any further, read the document I've attached to this step, "A Day in the Life of a Flux Reversal" by Count Zero. This document is pretty much the bible on how magnetic stripes work, and you need to understand how data is encoded on to them and the basic formatting of the tracks on a given magnetic stripe card. I'm going to go get a cup of coffee; have it read by the time I get back.


Finished? Good.

As you will have learned from your reading, data is encoded on to magnetic stripes by means of magnetic flux reversal in the segments on the stripe. When the card is swiped past the card reader, the changing magnetic field of the passing flux reversals induce a current in the reader element, which is then decoded into binary bits, and the original data stored on the magnetic stripe is reconstructed.

So, in order to emulate a particular magnetic stripe, all we need to do is find a way to recreate the pattern of the way its magnetic field changes as it's being swiped past the reader. How are we going to do this? With an electromagnet!

As you may already know, an electromagnet is basically just a solenoid (coil of wire). When an electric current is passed through the coil, a magnetic field is created. By turning the electromagnet on and off rapidly, we can replicate the changing magnetic field of a magnetic stripe swipe.

The final piece of this puzzle is how to control the electromagnet. Well, we're trying to recreate a particular waveform of current through the solenoid in order to create a particular waveform of magnetism. What's a common way of storing waveforms and converting them to electric current? Sound files! So, all we have to do is encode the highs and lows representing the desired flux reversal pattern into a .wav file and play it back on an iPod or similar music player through the solenoid.

Music players designed to play sound through headphones do not produce enough current to drive the electromagnet in this project, so we will also have to construct a basic amplifier that the signal must be passed through before going to the electromagnet.
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loko1908 months ago

software automatic wav (sound) to ascii (track2) those interested I'll see how it works with live video skype ,, software decode automatic wav to track2 ,,, contact icq 677360044

mardinli1 year ago

any body know how is it work ?

Jstrjad1 year ago
What should the power output be? I am looking to purchase an amp but I don;t want to get it to small to be useful.

Output Power: 150mW (16Ohm), 16mW (300Ohm)
SNR: >=95dB (A weighted)
Distortion: <0.009%(10mW)
FR: 10Hz-100kHz
Impedance: 16Ohm-300Ohm
Power Supply: Built-in rechargeable Li-ion battery
asconine4 years ago
There is an app for the iPhone called square and when you sign up for it they send you a card reader that plugs into your headphone jack ( see The way this app works is by converting the info on the mag-stripe into audio. So could you use an audio file recorded off of the Square card reader rather then using this C++ app to create one?
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Yup, totally.
goiano1 year ago
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lokivoid3 years ago
This type of spoofer will only work single track cards sadly.
So will the direct output from a Square Register cut it?
~CableGuy2 years ago
oh, and if you need a high-tolerance pre-amp for the reading process, Find a cassette player! and unsolder the nearest ic to the mechanical parts and the read head. Good luck!
~CableGuy2 years ago
dude you gave me BILLIONS of money! thanks!
janny1303 years ago
hello i was wondering if do anybody know anyting about tracks
maxell37754 years ago
Good Morning, Is there a way to get the data come straight from a usb port?, instead of having is to come from a audio source, that you could connect the spoofer to a USB port and send the data, and if it is not possible with this king of design, is there a USB SWIPE CARD like Justin longs in DIe Hard 4? when he tries to bypass woodlands server room door.

THank you
The first thing that comes to mind is a cheap USB sound card. All you'd need to do is crack it open and stuff a signal amp in, and depending on the particular card, a headphone jack that connects to the amp's output.

For the amp stage, you could cut size *way* down by using surface mount ICs and draw the power you need straight from the card's power supply (just make sure you keep the current below 500mA or you'll overload the USB port!)
Dlowe0893 years ago
would it be possible to amplify the output of the initial card reader to record directly as audio through a microphone jack (mixer, some form of audio in), and then run that recording of the magnetic pass into the mp3 player and spoofer? It seems to me like a perfectly reasonable analog solution. But I am no expert in magnetic stripes, nor did I read the "A Day in the Life of a Flux Reversal" article (later, I'm just browsing instructables right now.)
maxell37754 years ago
another form would be to be able to connect to the mini usb port of an android smart phone and be able to send the signal.
jaycwallace4 years ago
Someone should start a website with known data formats for different card types and make this conversion to audio track on the server side. Seems it would be pretty handy to know the data format and just fill out the form with the required information encoded on the card, since most the information is often pretty apparent and/or in sight. It would generate the audio track and you could play it locally wherever you are.
fub19854 years ago
you say that a old powered computer speakers can be used.. what do you mean by this?
Pooloop4 years ago
You could make a video tutorial explaining how to create the .Wav file
Pooloop4 years ago
where did you buy the parts?
Pooloop4 years ago
where a put the card code in the c++ code?
Giggles126 years ago
I think nerds are hot!
Fact Check:  We are ugly.
speak for yourself
now if only i could find a girl who was hot AND as smart as me
Nice to hear someone has some love for us, but it doesn't make the cold nights any warmer :P
exactly, knowing C++, C#, in highschool doesnt mean a thing to anyone.. we stay nerds cuz we know one day it will mean something..
 that kinda sorta just really made my day
nam20004 years ago
I wonder if you could somehow use the 12, 5 or 3.3 volt connections on the ipod 30 pin plug to power the device. It would be more expensive but smaller... here is a good website with the 30 pin port specs
seth3d6 years ago
WIP: I've created a PCB trace. The yellow lines signify where I'll be using wire jumps. If anyone is interested I'll post my results, negs, and Digi-Key part list.
There is an error in your pcb layout if i am not mistaken, the potentiometer is not hooked up as an adjuster, but rather as a simple 5k resistor, you need to change one of the traces to that center post instead.  I recommend Eagle for your pcb layout, it is lightweight and free, give it a try.
Seth3d, This would be excellent. But seeing as it has been going on 2 months since your last post, I still hope you provide the details :) Nonetheless, I have subscribed to your Instructable area, just waiting on you to create a Instructable with the details of your PCB board. In the interim, I will try and contact you otherwise. Thanks for offering this Seth3d :) Keep us the cool work :)
OK, here are the files in the zip file. The express PCB layout has top layer flipped for your printing convenience. I used the oxy-hydrogen-chloride etching method described here.

I haven't had much time recently to work with this much more. The amp is essentially a simple "square wave" modulator. I'm not 100% certain that the wave files would even work without the amplifier though others have stated it does with the right miniaturized electromagnet.

Additional materials not included in the part list include some solid core wire to use for jumpers, copper clad, an audio jack which was wrenched from the end of a broken headphone, and an LED with resistor to display power state. The LED can be excluded.
seth3d seth3d6 years ago
Here are both layers to the PCB, no sense wasting two sheets of transfer paper.
amp1b_copper_silk.pdf(612x792) 40 KB
Seth3d, You are the MAN! Very prompt reply indeed with all the necessary details :) Going to send you a Email shortly regarding some other stuff I think you'll find interesting. Thanks much Seth3d. You DA MAN!!!!!!!!!!!!!!!!!!!!!!!!!!! :)
is it possible to use these on say a card reader without a track?  I.e. a system wherein you simply hold the card to the reader?
Unfortunately, no.  That type of system is usually RFID (
finfan75 years ago
Could one use this setup but with a file that would enter all possible codes?  It might take a while to go through them all but unless there is a failure counter or a notification setup on the system it would be able to open any normal keycard door.
joe570056 years ago
Is the amplifier really necessary? if you put the coil a little closer to the reader, you only need as much power as the ipod normally gives to speakers. you could probably draw a suitable coil using conductive ink on a real [blank] card. depending on the size of the coil and the resistance of the lines, amplification should not be needed. Card readers use the same parts and very similar circuits as a cassette players, and you don't see any cd adapters use amplification or large coils, they just get the tiny coil very close.
could you put conductive ink on the magnetic strip on a card somehow and just have the coil at the end of the card so the card could go in the insertion readers instead of just the swipe readers like the movie showed?
not sure what you mean.
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