On Sep 8, 1:22*pm, David Cantrell wrote:

On Tue, Sep 07, 2010 at 03:46:30PM +0100,
wrote:
Seeing as its either (as I recall) a round green light or a
round red light, is there also a colour-blindness defence?
And do the readers not sometimes beep (but maybe twice?) also
on a failed read? *Hmm. Since I don't seem to remember very
clearly, perhaps I better hope there's a "hopelessly confused"
defence as well.

Sometimes they bleep once, sometimes twice, and the pitch is different.
I can't remember which way round it is though. *And in any case, the
machine is always on my deaf side, so I've got a nice excuse there if I
ever need one :-)

One bleep - success.

Two bleeps - fail.

Multiple rapid bleeps - a 'Zip' Oyster card for young people has been
presented.