Subject: Re: IR port
      Date: 8 Jun 97 16:43:31 GMT
      From: joehorn@mail.liberty.com
Newsgroups: comp.sys.hp48

Mike McGranahan <tmcgrana@ix.netcom.com> wrote:

> FYI, the sending IR diode transmits up to three feet, while the
> receiver only receives up to 6 inches.

That's right.  After 3 feet, the photons run out of momentum and just
stop, and float in the air like dust.  Although they are very small,
there are so many of them that within a few seconds they form a cloud
that impedes further transmission.  Since they are infrared photons,
you can't see the cloud, but walking into the cloud causes a warm
sensation on the skin.  Women have reported seeing these clouds as
"hot flashes" but I think that they're just making that up.  Leaving
the IR aimed at an object three feet away for a long time will
eventually cause the object (or your batteries) to get toasted.
This is the real reason that the Space Shuttle carries HP48's on board:
it can save them if the onboard computers *or* heating system goes out.

-Joe-
joehorn@mail.liberty.com