Though these " smart cards " are read in the same way as cards with magnetic stripes - that is, they are swiped through readers -they are capable of holding substantially more information. In 2000 computer chips were added to some credit cards. A strong magnet will align all of the magnets in the stripe, effectively erasing it. These stripes can be made of several different materials, but can all be damaged by strong magnets. While the first and second stripe contain "read-only" data, the third stripe is designed to be both written to and read while it is being swiped. The second and third stripes contain credit card or identification numbers, and are in binary coded decimal (BCD) format. The first stripe contains letters in the ANSI/ISO ALPHA format, and can contain a name or other text. On most cards, there are actually three independent stripes. These bits are used to represent letters and numbers just as they are in a computer. In this way, no matter how rapidly or slowly the user moves the card, so long as the card is moved at a relatively constant speed, the machine reader can differentiate a one from a zero. So, long pairs (zeroes) are exactly twice as long as short pairs (ones). At a high speed, the same pair will look shorter. At a low speed, a single high/low pair will look longer than it actually is. The card is usually swiped through the reader by a person's hand, and it is difficult or impossible to regulate the specific speed at which the card should be swiped. The difficulty in this system is that it depends on the reader measuring the distance between the peaks. Each pair is interpreted as a bit -a short pair as a binary "1" and a long pair as a binary "0." In this way, the preceding sequence of magnets encodes the bits "110". The reader converts the analog signal into a digital one by turning positive peaks into transitions from low to high and negative peaks into transitions from high to low.įinally, the reader measures the length of each high/low pair. The head senses the field at a north-north junction as a positive voltage and the field at a south-south junction as a negative one. A magnetic stripe reader has a head, much like the one in an audio tape player, which can detect that field. This results in a strong magnetic field at those junctions. The like poles of two magnets repel each other.
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#How to make a magnetic card reader and writer series#
If several sections of magnets are reversed, the stripe looks like a series of opposing magnets. If a single or a continuous group of bar magnets is reversed, the stripe will act like three opposing bar magnets. Unlike usual bar magnets, these tiny magnets can be made to reverse their polarity. The north pole of each magnet is therefore adjacent to the south pole of the next magnet and, like other bar magnets, all of the aligned magnets act as one larger magnet. In an empty, horizontal stripe, all of the bars are aligned left to right so that the north poles are facing one direction and the south poles the other. Like larger bar magnets, one end of each microscopic magnet is a north pole (N) and the other a south pole (S). Most other cards use this encoding as well. However, all credit, banking, and automated teller machine cards use the same type of encoding. High securityĬards encode the data in proprietary, undisclosed formats that prevent intruders from even reading the data. The magnets can be used to encode the data in an infinite number of ways. The magnetic stripe is actually an area of dense microscopic bar magnets, of which there are approximately 200 million per square inch.
![how to make a magnetic card reader and writer how to make a magnetic card reader and writer](http://images.51microshop.com/3156/product/20180409/deftun_msr_x6bt_mini_portable_msrx6bt_bluetooth_3_tracks_magnetic_credit_card_reader_writer_20180409165551745_1.jpg)
The stripes can also contain encrypted information and information not printed on the card which can only be created or read by specialized computers. The data cannot be read without a correctly programmed machine, and the cards must be created with special equipment, both of which make cards hard to falsify. Magnetic stripes make card usage much less prone to error because the data are not entered manually.
![how to make a magnetic card reader and writer how to make a magnetic card reader and writer](http://www.jmprime.co.uk/images/msr606_1.png)
By "swiping" the card through or inserting the card into a reader, a computer can read the data on the stripe. Most identification, credit, automated teller machine, and membership cards have a thin magnetic stripe across one side of the card. These cards are paired with readers and writers, and are used in a wide variety of applications for storing information. A magnetic stripe card is a card (e.g., a credit card) that contains a stripe of magnetically-encoded data.