11 Mar
2013
11 Mar
'13
6:55 p.m.
On 2013 Mar 11, at 6:27 PM, Chuck Guzis wrote:
On 03/11/2013 05:55 PM, Dave McGuire wrote:
Well, that's interesting. The roller is not an issue according to them.
Despite my own assumption about the roller being the problem, I
shouldn't have said one would think it could be done self-clocking
without a roller - I know it can be done self-clocking without a
roller: I looked back at my docs for the reader project and see I
picked the data & clk outputs off the read amps and interpreted them
with an assembly program - no roller sensing involved.
I believe the plastic wrap trick is to give
the rubber roller
in the
reader a better grip on the card, if the card is too slippery to
make it
turn.
Most of what I've read seems to say that it lowers the signal level
a bit and reduces some extraneous noise in the signal:
http://www.creditcards.com/credit-card-news/lick-plastic-bag-credit-
card-secrets-1273.php But the bit density on a credit card is very low in
comparison to a
floppy disk. I imagine that increasing the head-media separation
to the thickness of a bit of cling wrap would most likely make the
disk harder to read.