[simpits-tech] Flap gauge

[Matt Bailey]

Not exactly...keep in mind I don't have the schematic so I am just
going off what I observe.

To put the needle at any given point in its normal range of motion, one
of the three inputs will have FULL reference voltage (so 5v, in my
case), while the other two needles receive two different voltages that,
when combined, should equal the reference voltage. So a signal might
look like this:

Input A: 5v (fixed for a given 90* range)
Input B: 2v
Input C: 3v

B and C get adjusted to move the needle. It should be noted, however,
that you will still get a discrete position if inputs B and C don't add
up to the exact reference voltage (so they could be 3v and 4v, for
instance). You just limit how much you can move the needle if you are
only varying one input (or not "balancing" two of the inputs). You
could also ground two inputs and apply voltage to the third, and get
SOME movement.

Also, I discovered you can keep the "fixed" input at 0v/ground, rather
than ref voltage, and still have full needle control. You just change
your voltage distribution on the "active" inputs.

The "static" input moves around from A, to B, to C, depending on what
quadrant the needle needs to be in. Since I am only using 180* of
travel, I only need two quadrants (so my static input changes only
once). I guess since there are only three "quadrants" I shouldn't be
calling them quadrants. :)

I did some more testing after posting that video, and it appears that
while there are several ways you could drive the needle, my method
seems to be the "correct" way, as it provides a relatively predictable
and sequenced method for moving smoothly throughout the arc range. I'm
sure the instrument's guts were selected to work well with whatever
sort of mechanism was attached to the flaps on the real plane.

Matt


On Mon, 2 Jun 2014 17:28:53 +0000 (UTC)
wledzian1 at comcast.net wrote:

> Commenting on the description in the video and having the flap
> indicator wiring diagram in front of me, it looks like a straight-up
> three-phase device. Should the sum of all three equal some
> intermediate reference voltage? For example, assuming a ref voltage
> of 2.5v, you'd send 5v to phase X and 1.25v to each of Y and Z to for
> 0 deg, or 2.5v to Y and 3.75 to X and Z for 60 deg. 
> 
> ----- Original Message -----
> 
> From: "geneb" <geneb at deltasoft.com> 
> To: "Simulator Cockpit Builder's List" <simpits-tech at simpits.org> 
> Sent: Monday, June 2, 2014 6:39:52 AM 
> Subject: Re: [simpits-tech] Flap gauge 
> 
> On Mon, 2 Jun 2014, Matt Bailey wrote: 
> 
> > Just a tiny little victory with a Cessna flap indicator that I've 
> > actually had in the old sim for two years, but never had figured
> > out until now: 
> > 
> > https://www.youtube.com/watch?v=gqZV2s6hW_o 
> > 
> > Simple once I figured it out! :) 
> 
> Very cool! 
> 
> g. 
>