Unsurprisingly they didn’t like it when I asked them what the input capacitance of the chip they’re using is. I need to email them back about some PIN stuff for activation so I’m just going to tell them what I think it is based on the antenna dimensions.
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Taginfo that bitch and post… also try to get the atr value… though I guess it doesn’t matter since I’ll be taking a look at it soon enough
Do you plan on making a replacement antenna?
** TagInfo scan (version 4.24.6) 2020-10-04 12:57:30 **
Report Type: External
– IC INFO ------------------------------
IC manufacturer:
NXP Semiconductors
IC type:
ISO/IEC 14443 - probably personalized card
– NDEF ------------------------------
No NDEF data storage populated:
– EXTRA ------------------------------
– FULL SCAN ------------------------------
Technologies supported:
ISO/IEC 7816-4 compatible
ISO/IEC 14443-4 (Type A) compatible
ISO/IEC 14443-3 (Type A) compatible
ISO/IEC 14443-2 (Type A) compatible
Android technology information:
Tag description:
- TAG: Tech [android.nfc.tech.IsoDep, android.nfc.tech.NfcA]
- Maximum transceive length: 65279 bytes
- Default maximum transceive time-out: 618 ms
- Extended length APDUs supported
- Maximum transceive length: 253 bytes
- Default maximum transceive time-out: 618 ms
MIFARE Classic support present in Android
Detailed protocol information:
ID: 04:39:4D:AA:4C:5E:80
ATQA: 0x4800
SAK: 0x20
ATS: 0x0F788070020031C173C8400000900000
- Max. accepted frame size: 256 bytes (FSCI: 8)
- Supported receive rates:
- 106 kbit/s (DR: 1)
- Supported send rates:
- 106 kbit/s (DS: 1)
- SFGT: 302.0 us (SFGI: 0)
- FWT: 38.66 ms (FWI: 7)
- NAD not supported
- CID supported
- Historical bytes: 0x0031C173C84000009000 |␀1.s.@␀␀.␀|
I made the mistake of getting Amal excited. I just wanted an ordinary conversion with the existing antenna, but as soon as he saw that MOB package he started getting ideas.
It’s from NXP… so… that means 17pF or 70pF and yes I have antennas for both.
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I am genuinely excited for you also, It is sooo convenient having payment almost literally at your fingertips.
Speaking of which, where are you thinking of for placement?
Mine is in position 4.5 (ontop of the first metacarpal bone)
I banged it up a lot whilst it was healing, and probably should have gone for position 4.
Mine sits a little proud in 4.5 but is easy to swipe on payment terminals. Position 4 would be the same but would sit lower in the natural cavity.
Based on the dimensions the antenna should be around 1.534uH, which would put the input capacitance closer to 90-100pF. I could be off though. I haven’t confirmed if it’s a SmartMX2, and I don’t have the full datasheet handy for that anyway.
Thats a pity TagInfo didn’t grab the pF for you in the “Extra page” it does do for some, but I am also not sure how accurate it is.
How accurate have you found it in the past?
When the input capacitance is listed in TagInfo it’s always correct. It’s not being measured by the app, the value was inserted for that chip type by NXP.
That makes sense
I set my account up and loaded more funds without much difficulty. Here are the terms in a more digestible format.
No fee to load, but if you spend less than $250/month on the card they’ll charge you $4.95/month ($59.40/year)
I’m going to go ship the card to Amal now. I’ll pay for a snack and the actual shipping itself with the card and see how it goes.
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Be careful not to give the postal worker ideas when they see your package pays for stuff wirelessly, after you leave the post office 
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Actually you raise a good point.
My post worker purely felt my package 
and asked if it was a payment card…if so it would have to be security registered post for $$$ I said no!!
Not sure if that is just an international shipping issue, but might be something worth checking out @Satur9
I’d just be concerned that it would leave a trail of micropayments all the way to Amal’s. I’d cover it in tinfoil myself.
What is your assessment here?
My vimpaygo could be turned off, maybe purewrist has that feature aswell?
Here. I’m not sure what card it is, but if you can figure that out from the ATR I can get the datasheet from NXP and confirm.
I made a payment no problem. It was one of those antenna behind the LCD deals, and I got 3cm read range off the face.
There’s only $13 left on there and you need the pin. I’m not worried.
Yeah, the app & web interface allow you to temporarily deactivate the card. You can also transfer funds from one card to another if it becomes compromised.
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Interesting ok it’s probably a 70pF chip… that’s the highcap version NXP has for most smartcards. The calcs were prob a little off because of the large gaps between the wire loops