Hi:

Some comments about patents:

(1) I worked for a company that had microwave ferrites in it's product
line.
    The basic ferrite idea was patented by someone else.  We kept track
of
    who the end user was, and if the end user was the U.S. government,
we
    did not have to pay any fees.  I knew an engineer at another company
    that did a lot of government contract work who had a binder full of
    patents that he would use for jobs that were to be sold to the
government.

(2) Heathkit and EICO sold oscilloscope kits that were based on a
patented
    technology.  IMHO they could do this because the end user was an
individual.
    Anyone can use a patented technology for their own personal use.  As
    Don Lancaster says, for a patent holder to go to court and enforce
his
    patent is very costly.  I read somewhere that many companies located
    along the Mississippi river mainly because that patent court
district
    NEVER found for the patent holder.

(3)The Sunnyvale patent library files their patents by CLASS number
rather
   than the patent number (which is random in relation to anything).
This
   allows doing research easily, since all patents on a given topic are
   physically next to each other.  This is a great way to learn about a
   subject because very basic ideas are contained in the "claims"
section
   that do not show up in text books.  Some of the questions on the
piclist
   are canidates for patent searches if the end user is the questioner
or
   the U.S. government.

Have Fun,

Brooke