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

[Cris Harrison]

On 4/5/2012 12:17 AM, dabigboy at cox.net wrote:
> ---- 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.....
Nope aircraft instrument makes dont know what air core is..  They are 
mostly zero center voltmeters that measure voltage from some negitive 
voltage to some posistive voltage..
QUESTION?? Why hack something up, when you dont have to.
ANSWER: if its a volt meter drive a voltmeter.. btw NOT with pwm.. just 
voltage..
>> 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
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about the photos... the idea was to take pictures of the parts with the 
writing on it.. so I could read it..