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Magnetic head — Parallax Forums

Magnetic head

ArchiverArchiver Posts: 46,084
edited 2004-05-19 16:22 in General Discussion
I'm construct a system with card with magnetic stripe can anyone show me where i
can find magnetic head read/write/erase?

thank you


[noparse][[/noparse]Non-text portions of this message have been removed]

Comments

  • ArchiverArchiver Posts: 46,084
    edited 2004-05-18 22:55
    hello,
    does anyone have any idea how can i write to a
    magnetic stripe one bit with a simple circuit?
    I have a magnetic head one track who write & read.

    thanks

    ____________________________________________________________
    Do You Yahoo!?
  • ArchiverArchiver Posts: 46,084
    edited 2004-05-19 15:30
    Look up on the web information on how cassette recorders work. Due to the
    hysteresis in the magnetic head, the information is modulated on a "carrier
    frequency." But if you want digital info, you could try writing it without
    the carrier.
    Original Message
    From: andonis konstantinidis [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=X1isJup_zxvfgGhb3gG_eme5prf9qv4uwNtUVneONvl-oNSx1oVxa1-6wCboRfwhhTaZV3VauTi3Pjk]andoniskgr@y...[/url
    Sent: Tuesday, May 18, 2004 5:56 PM
    To: basicstamps@yahoogroups.com
    Subject: [noparse][[/noparse]basicstamps] magnetic head


    hello,
    does anyone have any idea how can i write to a
    magnetic stripe one bit with a simple circuit?
    I have a magnetic head one track who write & read.

    thanks

    ____________________________________________________________
    Do You Yahoo!?
  • ArchiverArchiver Posts: 46,084
    edited 2004-05-19 15:42
    Just to expand a bit....

    For analog recording on magnetic media, there's an ultrasonic bias frequency
    applied to the recording head (usually around 40 kHz or so) that is then
    modulated by the audio signal. This is done to keep the audio signal within
    the linear region of the magnetic record/playback process.

    For digital recording on magnetic media, they normally use saturation
    recording, where the record head is hit with enough current to saturate the
    magnetic media. If you scope at the signal on a floppy drive or hard disk
    head, it looks like distorted sine waves at two different frequencies, with
    one frequency representing "zero" and other frequency being "one".

    I've never messed with mag cards, but I assume it's pretty much the same
    thing....

    Mike Sokol
    mike@f...
    www.fitsandstarts.com


    " One should not increase, beyond what is necessary,
    the number of entities required to explain anything"...
    -William of Occam-

    Original Message
    From: "Grover Richardson" <grover.richardson@g...>
    To: <basicstamps@yahoogroups.com>
    Sent: Wednesday, May 19, 2004 10:30 AM
    Subject: RE: [noparse][[/noparse]basicstamps] magnetic head


    Look up on the web information on how cassette recorders work. Due to the
    hysteresis in the magnetic head, the information is modulated on a "carrier
    frequency." But if you want digital info, you could try writing it without
    the carrier.
    Original Message
    From: andonis konstantinidis [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=dh1UY4GYlrwSdIz0dn-I2ajght1cjHHTc75APh-FArLO1tiSDHMr3Ps5pko1hq-CGEVIkd3YiKgKWgA]andoniskgr@y...[/url
    Sent: Tuesday, May 18, 2004 5:56 PM
    To: basicstamps@yahoogroups.com
    Subject: [noparse][[/noparse]basicstamps] magnetic head


    hello,
    does anyone have any idea how can i write to a
    magnetic stripe one bit with a simple circuit?
    I have a magnetic head one track who write & read.

    thanks

    ____________________________________________________________
    Do You Yahoo!?
  • ArchiverArchiver Posts: 46,084
    edited 2004-05-19 16:22
    Is this a swipe card? ...If so, it is common to have a reference track
    i.e. two channels (a left head and right head). One channel would contain
    your data by shifting-up the frequency, shifting-down the frequency, or
    pulsing a fixed frequency to represent a "1" or "0". The other channel
    would be a baseline fixed frequency or fixed frequency burst representing
    a clock pulse. This way the "user"/machine could swipe the card at
    relatively any speed and the data can be recovered by simply comparing
    the two channels and noting the differences depending on the scheme used.


    >Just to expand a bit....
    >
    >For analog recording on magnetic media, there's an ultrasonic bias frequency
    >applied to the recording head (usually around 40 kHz or so) that is then
    >modulated by the audio signal. This is done to keep the audio signal within
    >the linear region of the magnetic record/playback process.
    >
    >For digital recording on magnetic media, they normally use saturation
    >recording, where the record head is hit with enough current to saturate the
    >magnetic media. If you scope at the signal on a floppy drive or hard disk
    >head, it looks like distorted sine waves at two different frequencies, with
    >one frequency representing "zero" and other frequency being "one".
    >
    >I've never messed with mag cards, but I assume it's pretty much the same
    >thing....
    >
    >Mike Sokol
    >mike@f...
    >www.fitsandstarts.com
    >
    >Look up on the web information on how cassette recorders work. Due to the
    >hysteresis in the magnetic head, the information is modulated on a "carrier
    >frequency." But if you want digital info, you could try writing it without
    >the carrier.
    >
    >hello,
    >does anyone have any idea how can i write to a
    >magnetic stripe one bit with a simple circuit?
    >I have a magnetic head one track who write & read.
    >
    >thanks
    >
    Beau Schwabe Mask Designer II National Semiconductor Corporation
    500 Pinnacle Court, Suite 525
    Mail Stop GA1
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