[Previous Months][Date Index][Thread Index][Join - Register][Login]
[Message Prev][Message Next][Thread Prev][Thread Next]

Re: [IP] pump and magnetic cards

On 15 Aug 00, at 7:55, Sam Skopp wrote:

> At 06:52 AM 08/15/00 email @ redacted wrote:
>  >The last couple
>  >of times I went running, I put my badge in the same little key pocket of my
>  >running shorts where I put my pump.  They were both in there, probably
>  >rubbing together a little but not much, for an hour at a time.  My badge
>  >has stopped working
> Pumps do have small electric motors and I believe that all these types of 
> motors generate a magnetic field. Whether the field it generates would be 
> strong enough to wipe out your card is hard to tell without doing some 
> experimenting... but it at least sounds possible. If we have any electrical 
> engineers out there, maybe we can get some more definitive information.

The magnetic field from a well shielded pump won't wipe out the mag strip.
On a hot day the mag strips can "fade out" due to the temperature rising 
above a critical point and allowing the magnetic domains to shift.  The strips
also wear out over time.  Sometimes a reader can also wipe a card, 
especially if the reader hasn't been demagnetized in a while - every read
actually weakens the pattern on the card and the heads become magnetized 
and accelerate the process.  It's just like the old cassette tape players, 
where a tape would get muddy sounding after a while if you didn't 
demagnetize the heads...

Rev. Randall Winchester
WD4HVA (email @ redacted)
for HELP or to subscribe/unsubscribe, contact: HELP@insulin-pumpers.org
send a DONATION http://www.Insulin-Pumpers.org/donate.shtml