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How The Card Is Made
Text & Typesetting
The source text is edited in Unix/ BSD vi using my
WYSIWYG extensions to ghostview/gv, editing in format
GroffonFreeBSD
(entirely free public
domain sourced programs, Using my berklix2.mk
make macros.
No Microsoft or other proprietary software used)
Physical Production
Made from 80 gram/ square metre paper, folded once & cut
to size, then heat sealed into plastic, hot lamination
pouches, used 2 (so far) alternate pouches:
Aluminium cooking foil cut to
same size as half paper length, & placed in the middle of
the folded paper, to reduce NFC RFID.
The metal foil in sealed plastic pouch is much slimmer
(0.26 mm) than a credit card (0.8 mm), so fits well in same
wallet slot as an NFC enabled credit card
(metal foil on outer side of wallet of course.
2017-06-27: first production size batch with aluminium foil Some foils are thicker than
others, I measured my aluminium:
Standard kitchen cooking foil, 0.0166 mm thick ( I folded a
strip to 64 thickness. Became 1.06 mm thick ) Brand name:
Maker Alu Folie, Exclusively for Plus, By/Gyartja: ProHa
GmbH, 71265 Renningen, Bar Code 4 008535 245343, 30m x
30cm
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lists . gnupg . org / pipermail / gnupg - users / 2015 -
April / 053496 . html
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lists . gnupg . org / pipermail / gnupg - users / 2015 -
April / 053501 . html
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RFID for Smart cards 13.56 MHz
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en . wikipedia . org / wiki / RFID_skimming #
RFID_blocking_wallets_and_sleeves -->
www .
omniscienceisbliss . org / rfid . html
"reduce the maximum range for reading, from about 1.5 feet
(50 cm) to 1-2 inches (3-5 cm)."
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Android supports lots of NFC RFID readers inc eg NFC
Reader.
as NFC chip is not behind NFC/RFID logo on card, & as
don't know where transponder on phone is, or if horizontal/
vertical (or square, like shop anti theft tags ?) its a bit
hit & miss to ascertain alignment.
As cards are stacked offset in most wallets, determine where
on the credit card the NFC chip is, for max overlap of the
foil.
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www . freebsd . org / cgi / ports . cgi ? query = NFC &
amp ; stype = all NFC support
svnweb
. freebsd . org / ports / head / devel / libnfc /
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Maybe expensive leather wallets with shielding won't use
foil ?
more likely to be ferrite or graphite coating or
similar.
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For shielding self powered mobile phones, even steel
boxes are insufficient, as eddy currents reproduce the
signal.
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Aluminium is also too conductive, so tends to reradiate
RF from the eddy currents.
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A screen needs to be conductive but also resistive to
convert the induced RF eddy currents to heat.
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Aluminium might work to screen credit cards as they are
powered from the RF, so cards need a strong signal. I'm told
The M field is used which drops off at the
inverse cube of distance, compared to the inverse square of
the E field.
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