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Old December 20th 07, 03:53 PM posted to rec.aviation.soaring
Martin Gregorie[_1_]
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Posts: 276
Default AoA keep it going!

Bill Daniels wrote:

20% of males suffer some degree of color blindness. A multi-color LED would
be difficult for them to interpret.

In any event, a 3-color LED is just 3 different LED's in the same case so
stacking 3 LED's in a vertical column is neither more nor less complicated.

That doesn't apply to them all.

There is a three lead version which is just a red and a green LED in one
package but there's also a two lead type where the applied voltage
controls the colour.

I remember experimenting with one of these as the output of an LM 358
op-amp and was able to get any colour across the range red to green from
it by adjusting the input voltage. I was thinking of the latter type and
that it would be easier to mount on the glare shield because it only
needs a 3mm hole or a very small enclosure.

I take you point about colour blindness though, but that would apply to
any tri-LED arrangement unless it was big enough for it to be obvious
just which LED was on.

I'd suggest that there are better displays to use: a 10 segment bar
graph type indicator should be best, arranged so that the segments
turned on from the bottom. The more segments that are on, the higher the
AOA. The option of making it flash as the AOA gets close to the stall
would be a nice feature. It could use LED or LCD technology. Best of
all, this type of display is small, so in many cases it could be placed
alongside the ASI without causing a panel rebuild. If the vertical
display was less than 6mm wide I could even get it into my Libelle's
panel between the T&B and the ASI, which is top center, just where I
like it.


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