This inspired me to whip out my soldering iron and attempt my shot at it. The LED shines brighter it seems like, but my phone won’t read the xSIID at all, just see the normal read cycle. I’ll check it up to a successful task in the form of knocking the rust off my soldering skills onto the antenna XD
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It may be that your right tail on the capacitor is not isolated to the single antenna wire. When I folded my cap over I put some paper over the coil just in case some of the enamel coating is weak and it interferes.
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It is isolated, just a bad angle looking at it.
I will try the paper though!
Also an odd thing, I get reads from the capacitor not the coil
I need this on my front door keypad so I don’t stand out in the heat for 5 minutes contorting my hand trying to get it to read only to eventually be defeated and just put the number code in.
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Oh thanks for this! I was literally just thinking of posting a thread asking about the possibilities of an NFC repeater or ‘booster’ since my phone as absolutely terrible NFC performance (on a good day I might be able to read my Apex Flex one out of every 10 tries).
This looks like an easy and cheap enough hack that even if it fails miserably I won’t care all that much.
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I’m already so ready for this post
begins reading
EDIT:
I mean you fuckin nailed it. Looks like the Capacitance of the chip you removed was 23.5pF so it’s perfect.
If anybody else is trying to make one and doesn’t know which capacitor to use, you can figure out the correct inductance using that calculator I made, or one you find online.
Once you have an idea of the inductance, you can figure out which capacitor to add to make it resonate at 13.56MHz using this.
Sorry I didn’t deliver on the crucifixion. Fuck up better next time and I’ll be back.
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Do they increase scanning range?
I guess you could describe it that way, for some types of transponders anyway. Particularly the small implantable kind. I don’t think you would get any difference in range if you were talking about a full size card, in fact you might get slightly less range with a full size card. It’s more of a magnetic field concentrator then booster or extender.
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I suppose the same principle applies to LF? Approximately what value should the capacitor be for let’s say one of those cheap EM4100 keyfob antenna? I don’t have a LCR meter 
That gives me ideas 
I have a load f old mifare cards …
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Something like this.
If it is genuinely a n EM4100 and not just a T5577 I’m not sure what the capacitance is, but you can find the datasheet somewhere.
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It didn’t cross my mind to check the datasheet 
. Thanks!
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If it is a T5577
you can find it under
T for T5577 in here
To confirm whether your fob is a t5577 or EM 4100, run
lf t5 detect
on a proxmark
but Satur9s link above for his post will be very useful for guiding you through your project
Replaced the ceramic with an smd capacitor and it honestly feels like the range has increased.
But none the less this was incredibly successful for such little invested time.
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Not that I have seen on the forum.
I have a few “Bullseye” stickers that I considered using, but went with the copperr wire because I had ceramic caps, and I wasn’t going to achieve the low profile I was after for the whole thing plus the stronger mechanical bond (solder) onto the foil would actually become the weak point; also they may be fine secured in phone case etc, but the stickers are not very robust.
I decided it was a better experiment than a “product”
Amal did look at / consider a sticker
and Satur9 at a flexible pcb version , but thats probably down the list for both of them
If someone has silicone molding skills they could make Iphone case with an integrated nfc booster I feel like there’s demand for that
If you can get the solder to work on that foil. IIRC, it’s aluminum and that’s not easy to solder, if that’s even possible.
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