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  • RFID for starting PC

    I've had this idea for a while now, just can't figure out out how to 'tweak it'
    Using RFID (radio freq ID) (same as the "try to steal me detectors you see at the exit of most stores)
    Idea being::: RF detector in car,,,, the little metal thingy (for lack of the technical name) in your wallet.... as you walk towards your car,, the alarm turns off, doors unlock and your carputer starts up!!
    when you get out of your car and walk away, alarm turns on, doors lock, carputer does whatever you pre-determine!!
    sounds to me like an excellent idea,, I got all the **** worked out,, all except for the fact that most/all RFID kits/circuits only have a limit of about roughly 100mm (4") (which sucks, coz with that limit, to unlock your door, you'd probably have to rub your arse up against your car window, not my idea of a good look in a public place :~))
    anybody got any ideas how to extend the limit so that when you are about 3,4 or 5 metres away from your car it detects you??

    purpose== usefullness + geek factor :-)

    edit-- temporary brainwave,,, have one also in your house,, when you get home after work,, drive into driveway,, the one in your house also detects you and unlocks your front door,, as you walk towards your home pc it resumes from standby,, the possibilities are endless,, only the damn 4" limit
    I'm not sure who I stole my avatar from, but I hope they don't mind, I figured it sums me up perfectly...... a pi$$edIdiot

  • #2
    The problem is that you'd need a computer or device to read the RFID chip be on and functioning in order to start the car or the computer or whatever.

    To pull off what you're talking about, you're going to need to design a device with an extremely low power draw that will detect your RFID chip(s) and initiate startup of whatever you indicate. It would basically function similarly to a car alarm, only there's no button to press.
    Have you looked in the FAQ yet?
    How about the Wiki?



    Under normal circumstances, a signature would go here.

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    • #3
      I've been looking at these,,
      http://www.jaycar.com.au/productView...Max=&SUBCATID=

      http://www.jaycar.com.au/productView...Max=&SUBCATID=

      http://www.jaycar.com.au/productView...Max=&SUBCATID=

      .....run on 12 volt,,(can run on SLA,, charge via alternator or even solar power)and i'm figuring, if I went to the trouble of installing a car PC, and the extreme trouble of running all the other crazy, whacked out, please shoot me now projects, then theres really nothing stopping me from running something like this apart from the fact that I suck at making antennas, amplifying RF's etc etc
      I honestly don't think i need a PC to run it, I've come across a lot of (unnatended) boom gates that use rfid and there's no pc to be seen (god help it if there was one) I LOVE problems, so i'm pretty sure I can figure out a way to make something like this to throw a relay or something, which will give me what i want, only, as i said before,, i suck at RF,,all i want is to extend it's limit
      I'm not sure who I stole my avatar from, but I hope they don't mind, I figured it sums me up perfectly...... a pi$$edIdiot

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      • #4
        Nice idea, but it has some things in it you have to deal with. For a start: I think you only looked at short-range passive RFID (mostly used for Access & Control). Short Range is mostly limited to about 10 cm, sometimes a bit more. Besides there is Mid Range and even Long Range. For example with the credit card RFID tag you mention, we have a gate with its antenna's at a distance of about 1.85 m.

        But... what you need to accomplish your goals is active RFID Tags. These have a range of over 50 meters!
        Most readers are RS232 or RS485 so you need a controller to do something with the ID the tag sends.

        By the way... what you want is already being used in cars, for example Renault. No, not the starting, but opening the doors, and starting the car without putting a key in place.

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        • #5
          I wonder how far the RFID module in the second link you posted will reach. Also, is there an external bit writer device needed to program the module to the card? Or I wonder if it's more of like hold down a button for a certain amont of time with the card in range...

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          • #6
            Originally posted by XxAndyxX
            I wonder how far the RFID module in the second link you posted will reach. Also, is there an external bit writer device needed to program the module to the card? Or I wonder if it's more of like hold down a button for a certain amont of time with the card in range...
            It works with passive tags, it's quit a small coupler, so my guess is 40-50 cm max.. I even think it won't be more then 10 cm.

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            • #7
              Ive been playing around with this idea for a while. NOt so much that I want the car and carputer on but just to unlock the door then I could have a push start or something.

              Passive tags will not work, I read about one guy who had one implanted into his hand so when he reached for the knob the door opened. You can buy a very small active unit (prob be able to fit it into a keyfob). Theres always the danger of someone droping in and intercepting your rfid signiture, but if its only a very small amount of people that have it i dont think that would be a problem. Usually with the active tags you can alter the total distance, Im thinking an arms length would be good enough. You can also rig the car to have a dialog with the rfid tag for further protection (some premade units have this option built in) So unless someone is hugging you youd be fine.

              The only problem I can see is with the current draw (assuming youd leave the car for a few days) so youd need some sort of shut down for the system if the battery power ever droped to the point of just being able to start the car.

              If you have keyless entery it should be doable to just have a relay set up that would push the car open button on the factory system.

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