Unlocking windows 8 tablet using NFC ring



  • @Lokki, any recommendations on antenna ?

    I did purchase the ACR122, Ill Pop that open to see what kind of antenna it has, but I'm guessing another circuit board. but to do this mod Will I need a loose antenna ?


  • Community Helper

    Yeah, you're most likely going to need to form your own antenna if you can't acquire one from somewhere. The "standard" 5 turns at ~50mm diameter coiled antenna might be interesting to try, refer to my sweet spot tester post that's here somewhere. If I get a moment I'll link it. I formed mine out of relatively thick transformer wrapping wire, that stuff is enamel coated so you don't get short circuits between loops.



  • @Lokki said:

    Yeah, you're most likely going to need to form your own antenna.

    That's hard core uber geek !!!

    ill give it a shot!!!


  • Community Helper

    Ah, here 'tis. For some reason I was looking for a picture. What I'm talking about is the horrid looking big test tag with the 5mm LED. Something like that connected to the board instead of a LED might be interesting to test.

    Thread with video here



  • @Lokki said:

    Ah, here 'tis. For some reason I was looking for a picture. What I'm talking about is the horrid looking big test tag with the 5mm LED. Something like that connected to the board instead of a LED might be interesting to test.

    Thread with video here

    @Lokki, thanks for that, I get the idea of what I have to do now. so basically
    1- I cut the antenna wires on the NFC express
    2- I get some transformer wrapping wire.(is that like from a special electrical store like a dick smiths or any hardware store?)
    3- I take 1 piece of wire, run it around 5 times to make a circle but try to make the circle have a 50mm diameter.
    4- I solder both ends to where I cut the NFC express antenna off

    And then the magic happens ?

    Cheers Jason


  • Community Helper

    If Dick Smith still sell useful electronic parts where you are... Jaycar/tandy(radio shack) or anything similar should do it. If you can't find proper wrapping wire you might get away with some solid core wire of a reasonably heavy gauge.
    When you make your cut, try and leave a good amount of track on the top there from the vias for you to solder to, and bear in mind it's going to be delicate after the cutting, scraping and heat from soldering - so don't move your new antenna around too much once it's connected.

    Sounds like you've pretty much got the steps as they should be. Good luck, dude. Prepare to become a practitioner of the Dark Arts.

    Actually, this project shows a 'normal' home made antenna for 125kHz. What you're doing with the wire is basically the same, just you're making yours smaller so that it couples with the ring better than a large antenna would.



  • @Lokki good point, I will have to get to JayCar



  • @Lokki so the guys at JayCar had no idea what i was talking about. they were trying to sell me normal copper wire. Instead I bought a pre wound inductor, I figure at least its probably the correct type of wire and I can just unwind it. and use it.

    what do you think ?

    link text

    Cheers


  • Community Helper

    yeah, that'd do it man.
    I've been trying to find something I saw, where an inductor was used as an antenna.



  • @Lokki said:

    yeah, that'd do it man.
    I've been trying to find something I saw, where an inductor was used as an antenna.

    so this is the coil with a 5 cm diamater, 5 turns.

    basically I just solder this onto the spot you pointed out before. FYI, I wont cry if I kill it.

    link text


  • Community Helper

    yup, basically do that and have a play with it.
    Possible results could include magic smoke release. But something should happen. Test it with a mifare card too, to see what goes on.

    You're gonna have to strip and tin that other end.



  • @Lokki said:

    You're gonna have to strip and tin that other end.

    any tips on doing that ?


  • Community Helper

    just apply heat and solder for a little longer then usual before you try to connect it. You should see the enamel melt back and the wire take up solder.


  • Community Helper

    Once you verify whether it works or not you can start playing with different shapes and sizes for the coil. Have a look at @MrStein's thread with the nfc arduino for tips.



  • @Lokki said:

    just apply heat and solder for a little longer then usual before you try to connect it. You should see the enamel melt back and the wire take up solder.

    you know last time I tried to solder a basic circuit board together it only ran for about a minute until a capacitor popped. Hopefully I do better this time. with it just being an aerial and all.


  • Community Helper

    Lol. You'll be fine!



  • @Lokki , @johnyma22

    some awesome progress with the NFC express, readability on the inlay is way up, not enough for the ring yet though...sadly, can either if you make any suggestions re antenna, see pic followed by the video of it in action.

    Cheers Jason

    Pic
    link text

    video
    video here



  • the video link seems not to be working, its

    https://dl.dropboxusercontent.com/u/39091739/NFCRingHack1.mp4

    cheers


  • Community Helper

    Sorry, was trying to make the video and pic show up properly ;-)
    put an exclamation mark before the pictures to get them to show.
    Good vid, dude - ok lets make the diameter of the coil about half that size for the next attempt, basically making it smaller will concentrate the RF field and make it more likely to interact with the ring. You'll get to a point though where the coil is too small and simply doesn't work properly, so start with half the size and see how that goes.



  • @Lokki said:

    Sorry, was trying to make the video and pic show up properly ;-)
    put an exclamation mark before the pictures to get them to show.
    Good vid, dude - ok lets make the diameter of the coil about half that size for the next attempt, basically making it smaller will concentrate the RF field and make it more likely to interact with the ring. You'll get to a point though where the coil is too small and simply doesn't work properly, so start with half the size and see how that goes.

    OK will give that a shot, Its going to have to be next week now when I get another free night, Thanks for all your help this far :)

    Iv put it back in the case now and ever through the case the inlay is working, where as it wasn't before, so things are definitely better.

    Cheers Jason