[simpits-tech] Common aviation gauges that are air-core?

[dabigboy at cox.net]

---- Cris Harrison <phoenixcomm at gmail.com> wrote: 
> >
> gene not really.. the needles in CDI for ILS and all the FLAGS in both 
> the HSI, and VSI are just meter movements why mess about changing them 
> to - air core motors when all you do I hook a DAC (Digital to Analog 
> Converter and drive them... EASY PEASY!!

Cris, as it happens, I was just wondering about VOR/CDI gauges....it seems like they would be air-core, but if they are simply "volt meters" then that is super easy to drive! Except for this part.....

> just remember that pointers in the CDI are zero center ie + 0 - so you 
> need a DAC with bipolar output..
> and your flags are uni-polar,
> ------Data Bus----{ DAC }=(meter movement)
> 
> a quick present from google: http://pdfserv.maxim-ic.com/en/an/AN2398.pdf

.........but I have already run into this with getting more than 120* or so out of my current air core instrument. But if I understand it correctly, I can use an H-bridge to make this work. Also, instead of a DAC, I believe I can just use pulse-width modulation to run the things...doing that currently with air cores and the Arduino.

I did come across an ebay listing for the 10-pack engine/system meters that Bonanzas and other Beechcraft planes have....looking at the back panel, it looks like they are simply meter instruments as well, very simple to drive.

Matt