[simpits-tech] Need a power supply...

[Cris Harrison]

On 04/05/2014 10:46 AM, Matt Bailey wrote:
> On Fri, 4 Apr 2014 08:47:04 -0700 (PDT)
> geneb <geneb at deltasoft.com> wrote:
>
>> I need to get my hands on a 115v 400HZ, single phase power supply for
>> the ADI in the F-15.  Anyone here have one for sale?
>>
>> Matt, what system are you using for driving synchros right now?  The
>> ADI has four synchro inputs on it.  I'm wondering if it wouldn't be
>> easier to get four synchro transmitters(?) and drive them with
>> stepper motors...
> Not sure which Matt you are addressing, but I have been playing with
> synchros, so I will chime in. :)
>
> First, synchros don't seem to care what frequency you run them at.
> 400hz was selected (as I'm sure you know) because of various harmonics
> and interference concerns on real aircraft systems. I have a very
> coarse method right now to READ synchro/resolver position (which you'll
> have to do if you drive the synchros electronically), and they respond
> just about as well at frequencies from the tens of hertz all the way up
> to thousands. I can read position, but I need an improved circuit that
> allows waveform analysis in order to know what quadrant the
> resolver/synchro is in, and to make precise measurements near the end
> of each quadrant. (I am working on one, with help from an Arduino guy
> who made a metal detector).
>
> Voltage, at least for resolvers, also does not seem to be a huge
> factor. My little test circuit started out switching something close to
> the resolver's labeled voltage (it was incredibly low, like 2.3 volts
> or something), but I can also run the Arduino's 5v logic through it no
> problem. Same for resolvers with HIGHER rated voltages (a 26v AC
> resolver responds just fine to 5v logic).
>
> In fact, resolvers don't even seem to care about the SHAPE of the wave
> you are sending them. The coarse method I use now is actually driven by
> a SQUARE wave produced ENTIRELY by an Arduino...! As I recall, the sine
> wave produced by a function generator yielded *slightly* more precise
> readings, but like I said, I still need a different circuit design
> anyway to yield sufficiently precise results.
>
> Now, most synchros are LABELED at a particular voltage and frequency,
> but these are just the DESIGN parameters. The synchro or resolver may
> or may not work OK in other parameters. I have not tried driving a
> synchro with oddball voltages/frequencies yet, I suspect there may be a
> danger of sending too MUCH voltage. Too little would probably just not
> move the synchro, or move it very slowly.
>
> If you have a synchro or two lying around extra (that are labeled
> 115vac), try powering them up with 115/60 house voltage! Of course, you
> really need a control transmitter synchro to position the first
> synchro, to see if it's actually working.
>
> If you are really set on 400hz, I see 1-phase 400hz inverters on ebay
> from time to time...obviously a static inverter is desirable, but the
> old rotary inverters (like what's in my Sabreliner) come a little
> cheaper, like under $200. You could get a cheap 750VA "instrument
> inverter"...my Sabreliner has one of these, and I was able to run it
> with a 27.2v 54A DC power supply.
>
> As far as manually positioning control transmitter synchros, this is
> definitely an option. It will be as smooth and precise as how you move
> the CX. I've seen it done only with servos so far. Good solution, but
> it does limit you to <360*. Instead of dealing with steppers (which can
> "stutter" and look not-smooth, and require some sort of
> position-sensing additions anyway), you might want to consider just a
> plain old DC motor geared to the CX, and a Hall sensor geared or
> connected directly (1:1) to the CX. Obviously, the Hall would be setup
> for angular sensing as opposed to linear. I have such a sensor, it's on
> the back burner...but it does allow position sensing over 360*,
> according to its documentation. I sorta set it aside once I got
> seriously into reading and driving synchros/resolvers. I will probably
> end up using it for some of my non-synchro real instruments that have
> motors in them.
Matt: I would be very interested in seeing your code (if you don't mind) 
running on the Arduino.  I would love to try it..
Cris H.
www.element14.com/community/people/phoenixcomm/blog/2013/04/29/nexgen-flight-simulator-understanding-syncrhos
>> I've also gotten the SFS wire out DONE!  Check it out here:
>> http://www.f15sim.com/?p=315
> NICE stuff, it hardly looks like a reproduction part! I really wish I
> had some milling equipment here, or at least a good 3D printer...I
> could make my old sim some nice bezels and controls. :)
>