Blog - All Comments

RE: NFC antenna tuning without a VNA

Luka851 — Mon, 11 May 2026 21:32:02 GMT

Hi, lot of time has passed. Have you ever tried to measure impedance of a hand winded copper coil? I have an nfc keyfob, blue ones that usually come with the reader, I wanted to measure its impedance for learning purposes, and then to tune it fo it matches the rc5180 reader module matching circuit. Do you know if it is possible to measure it without VNA, and then what shall I use and how? with just a coild be enough, should it have an nfc chip on it, or resistors and capasitors? thank you

RE: Blue Payment, paying for a vend via RFID card

malekses — Wed, 15 Jun 2022 18:01:46 GMT

Hi,

thank you for sharing the idea.

could you please share the code here?

RE: Using Disney park tickets/keycards as NFC task triggers on Android phones

Ryanroy — Tue, 08 Feb 2022 09:46:13 GMT

Thanks for sharing. much appreciated

RE: Using Disney park tickets/keycards as NFC task triggers on Android phones

jamielanger — Tue, 11 Feb 2020 17:41:16 GMT

That's a great discovery. Will try it. It is more time saving to recover password and efficient for android users.

RE: NFC antenna tuning without a VNA

Fred27 — Mon, 30 Dec 2019 15:00:23 GMT

I've updated the guide as I've since discovered that cheap VNAs exist. The $50 NanoVNA is great for NFC antenna matching.

RE: NFC antenna tuning without a VNA

mpandrews — Thu, 12 Dec 2019 03:25:15 GMT

Why must the impedance of the antenna be 50 Ohms and how is the value of the imaginary part calculated from the inductance?

RE: NFC-Badge - Update your badge with your smartphone - Using the ST X-NUCLEO-NFC02A1

jomoenginer — Wed, 11 Sep 2019 21:43:17 GMT

It's the difference between a 3.3v shield and a 5v shield. The X-NUCLEO-NFC02A1 is designed to the STM Nucleo boards which are 3.3v boards, or other Arduino based 3.3v boards, thus only supports 3.3v shields where as the Arduino Uno is a 5v board and you should only use 5v shields with it.

Outside of modifying the shield as you did to run on a 5v Arduino board, the other option is to convert the Arduino board to a 3.3v board by changing the 5v regulator for a 3.3v regulator.

Ex:

https://learn.adafruit.com/arduino-tips-tricks-and-techniques/3-3v-conversion?view=all

RE: NFC-Badge - Update your badge with your smartphone - Using the ST X-NUCLEO-NFC02A1

clem57 — Wed, 11 Sep 2019 08:52:42 GMT

Nice mod to an existing project. Thumbs up[View:/resized-image/__size/16x16/__key/commentfiles/f7d226abd59f475c9d224a79e3f0ec07-d331245c-0856-4467-b06f-7ed2baa87e3b/contentimage_5F00_930.png:16:16]

RE: Using Disney park tickets/keycards as NFC task triggers on Android phones

Matt — Fri, 21 Jun 2019 08:13:12 GMT

Thanks for the feedback [View:/resized-image/__size/16x16/__key/commentfiles/f7d226abd59f475c9d224a79e3f0ec07-869fd659-201b-4cc0-bac4-a4908a4c939a/contentimage_5F00_1.png:16:16] Yeah, it's a good app.. it's just the name of it makes it very hard to Google for anything about it [View:/resized-image/__size/16x16/__key/commentfiles/f7d226abd59f475c9d224a79e3f0ec07-869fd659-201b-4cc0-bac4-a4908a4c939a/contentimage_5F00_53.png:16:16]

RE: Using Disney park tickets/keycards as NFC task triggers on Android phones

BigG — Thu, 20 Jun 2019 16:56:41 GMT

Thanks for sharing. I wasn't aware of that app. A great demo too.

I see their website has pretty good documentation too https://llamalab.com/automate/

RE: Using Disney park tickets/keycards as NFC task triggers on Android phones

neilk — Thu, 20 Jun 2019 16:49:04 GMT

Very interesting. Prompted me to test a wristband I thought had NFC, but when I enable NFC on my phone, it doesn't react to the wristband.

Thanks for sharing this - i am also going to investigate the Automate App

Neil

RE: Using Disney park tickets/keycards as NFC task triggers on Android phones

genebren — Thu, 20 Jun 2019 15:35:04 GMT

Pretty cool snooping and discovery.

RE: Using Disney park tickets/keycards as NFC task triggers on Android phones

shabaz — Thu, 20 Jun 2019 14:31:55 GMT

Hi Matt,

Nice video! I'd not seen that app before. Looking forward to trying this out with some old NFC cards.

RE: NFC and The Raspberry Pi

ipv1 — Sat, 15 Jun 2019 19:58:36 GMT

Thank you [mention:d214a0a0f5594ee19515b2a3782e7070:e9ed411860ed4f2ba0265705b8793d05] & [mention:4966e6ad97f64dac9ea8919abb220e1d:e9ed411860ed4f2ba0265705b8793d05]

I am glad you liked project. This one took a lot more effort than I would have liked but the result is something I can be happy about and is more complete than many of my other projects.

Thank you for the positive feedback.

RE: NFC and The Raspberry Pi

DAB — Sat, 15 Jun 2019 18:25:00 GMT

Nice project.

I like the simplistic packaging.

DAB