[simpits-tech] converting instruments

[Gene Buckle]

On Mon, 21 Oct 2002, Tim Soetaert wrote:

> Hi guys, My name is Tim Soetaert from Belgium (callsign "Fouga"). I am
> in the research stage of building my own Fouga cockpit sim. Since all of
> the instruments are old gauges from the 1950's, i'm looking for info or
> articles about converting normal instruments into computer driven ones.
> I would like to start with the altitude Gauge. it has readings for
> 10.000, 1000 and 100's feet. the inside has some kind of barometric
> element. Anyone know how to convert it? Can i use an USB connection? do
> i use some kind of electric motor? please help, Fouga
> www.fougamagister.be
>
Tim, altimeters are interesting beasts.  The main problem is that you need
feedback from the device.  What this means is that the computer has no way
of knowing what the instrument is currently reading.  One way around this
is to figure out a method of having a "zero" point set.  This is where the
instrument would read 0 feet and at the same time close a contact that
told the computer where zero was.  From here you can figure out how many
steps or motor revolutions need to happen for x feet of display.

You may find it easier to scratch build a look-alike instead of modifying
the original.  However, since I've not done this (yet), I'm not 100% of
the best way to go about it.

g.