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rfid help??

Discussion in 'Radio and Wireless' started by tmartellc, Dec 2, 2010.

  1. tmartellc

    tmartellc

    3
    0
    Dec 2, 2010
    I am completely lost. I'm doing a project using rfid. I want to use a transponder powerd by 12v that will power a 12v light from at least 3 feet away from the reader and cut off when I gain distance.:confused: I found this kit on the net but it doesnt have the distance I need:

    The kit consists of an RFID reader coupled with a 125KHz antenna. The kit comes with two RFID keyfob tags. Extra tags are available in two formats, Keyfob or Disc. The Keyfob as it's name suggests can be attached to a keyring, whilst the Disc can be put into a wallet or purse.

    The read range is 50mm - 75mm.

    The tags have unique serial numbers allowing only tags which have been programmed in to the RFID reader by the master programming fob to activate the reader output.

    The reader has a 12v output which is active for as long as the keyfob is held in front of the RFID reader's antenna.

    This output can be used to drive a relay which in turn unlocks a door latch.

    The reader unit runs from 9V to 15V DC.

    You can program up to 25 RFID keyfobs per reader.


    I need to atleast have a distance of a foot or two. Thanks
     
    Last edited: Dec 2, 2010
  2. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,192
    2,694
    Jan 21, 2010
    For larger range, you typically have larger antenna coils (the normal antenna is a coil) and/or higher power.

    The range is limited mostly because the signal received by the RFID tag, not only has to be received, but has to power the electronics, and power the returned signal.
     
  3. tmartellc

    tmartellc

    3
    0
    Dec 2, 2010
    Thanks Steve,

    Can I change the antenna on the kit and get a battery powered keyfob for longer range:confused:


    The kit consists of an RFID reader coupled with a 125KHz antenna. The kit comes with two RFID keyfob tags. Extra tags are available in two formats, Keyfob or Disc. The Keyfob as it's name suggests can be attached to a keyring, whilst the Disc can be put into a wallet or purse.

    The read range is 50mm - 75mm.

    The tags have unique serial numbers allowing only tags which have been programmed in to the RFID reader by the master programming fob to activate the reader output.

    The reader has a 12v output which is active for as long as the keyfob is held in front of the RFID reader's antenna.

    This output can be used to drive a relay which in turn unlocks a door latch.

    The reader unit runs from 9V to 15V DC.

    You can program up to 25 RFID keyfobs per reader


    What would someone knowledgeable suggest on how to get a 1ft and or 3ft range ?
     
    Last edited: Dec 2, 2010
  4. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,192
    2,694
    Jan 21, 2010
    I can't tell you if it will be better or worse, but you could try creating a larger coil, with the same number of turns.

    It may give you more range, or it may just reduce the flux to such an extent that it won't work at all.

    You would be best off trying to increase the power too. This would (practically) involve finding out what chip that is used and then trying to find a datasheet telling you how to deliver higher power from it.

    Do you know what chip is used?
     
  5. tmartellc

    tmartellc

    3
    0
    Dec 2, 2010
    I was thinking that about the coil but I didn't know it may make it worse. I think I got ahead of myself proposing this as my project, I have to do some more research. Hopefully I find someone who has already built this or something close.no idea about the chip, thanks again
     
    Last edited: Dec 2, 2010
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