[simpits-tech] Wiring of POT and EPL

[Gene Buckle]

Martin, there is _no_ such thing as a DC synchro.  DC cannot provide the
sine waves that the device _requires_ to operate.  The only way you could
even think of it working is if you used a high frequency square wave and
all that is is AC with "edges".  At 60Hz AC a synchro will function, but
it "buzzes" and gets warm very quickly.  At straight DC it would probably
flash one of the six internal coils to slag.

A synchro functions by moving a stator to a "null" point.  This null point
occurs when two sine waves cancel each other out.  For this to happen, the
input current to the device MUST be AC.  There is no way around it.  This
is how a synchro resolver or reciever work.  A syncro transmitter actually
changes the null point when you manually rotate the stator.  For example,
you can hook a resolver directly to a transmitter (with the 400Hz AC
supply in the middle) and watch the shaft of the resolver move in perfect
synchronization with the stator (shaft) in the transmitter as you turn it.

Do you have a picture of this device you have?  I'd like to see it.

tnx.

g.


 On Fri, 28 Feb 2003, Martin Ingold wrote:

> Well yes, they are all labeled with 400Hz on the outside. Though they don't use it..
> believe me. Pin outs of the manufacturers of the instrument show DC voltage used too....
> there's absolutely no need for 400Hz on ANY Sim-Instrument I have, and yes, they DO have
> Synchros in them.... I was worried about needing to use 400Hz when I first saw them...
> Pin-Outs and "reverse engineering" of circuits teached me the opposite... looks like they
> are avoiding that stuff for the simulators...
>
> Martin
>
> Gene Buckle wrote:
>
> > > Not quite... the sim stuff that uses synchros feeds them with DC
> > > voltage, which causes the synchro to spit out a sin/cos (I think)
> > > signal.... The instruments and stuff I have from Sims have lot's of
> > > synchros in, and not one of them needs 400Hz or makes that current
> > > internaly.
> >
> > Every synchro I have is rated for either 28 or 115 volts AC at 400Hz.  No
> > commercial flight simulator I've ever seen drives a real synchro on DC.
> > They way they're wired precludes them from producing a correct signal on
> > DC. (DC has no sine wave, which the synchro manipulates or is manipulated
> > by)  If it's working on DC, then it's not a synchro.
> >
> > g.
> >
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