[simpits-tech] Zero point on a two needle altimeter

[Gene Buckle]

You guys are missing the obvious.  Buy a cheap battery powered clock drive
and drop the original motor out of it and drive it with a stepper motor.

g.


On Sat, 26 Oct 2002, Matt Bailey wrote:

> Interesting ideas on this subject! One thing to keep in mind, the
> relationship of the turning of the hands of an altimeter is always the
> same, the hundreds needle always makes 10 revolutions per one revolution
> of the thousands needle etc. So you really only need one connection to
> the motor and sensor (perhaps on the hundreds needle, for precision) and
> just drive the other needles off that, using gears or pulleys. Also, if
> you had a way to measure the position of the ten thousands needle, your
> software would always know where that needle was and hence where the
> other needles are...only problem might be resolution since there is so
> much difference between this needle and the hundreds needle, for
> instance. But without having to count the number of revolutions for this
> needle, you would get a range of 100,000 feet. Quite sufficient for
> anything other than very high performance fighters (like the F-104) or
> spacecraft.
>
> 	-Matt Bailey
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