All this fluxgate compass stuff is real interesting, but a little
too late for me.  When in high school I was intrigued with the automatic
pilot on my father's boat.  It had a floating magnet compass with a card
with a flag on it.  The base of the compass had lamp and photocell
assembly that could rotate so the flag on the card would block half the
light from the lamp to the photocell.  The rotation of the base was
connected to the motor that would steer the rudders.  There was a clutch
between the motor and the rudders.  The clutch served a couple purposes.
One was that it let you turn the autopilot off!  The second was that if
the clutch was off, the autopilot continued to adjust the compass base so
the flag half covered the photocell.  When you turned the clutch back on,
the boat would keep going in the current direction.
        Anyway, I wanted to make a fluxgate automatic pilot.
Unfortunately, my father's boat sank last November when it hit a sandbar
going into Tamales Bay in fog.


Harold