[simpits-tech] Controlling synchros

[Cris Harrison]

Hi Simon, et al.

I did a D/S converter in college more than a few year ago. I had been 
working for Grumman (X29 Demonstrator) in the Cockpit Integration Lab. 
and I acdently put
400Hz 3phase power on the  ADI and it started to rotate. I realized my 
bobo and removed it, while thanking and swearing under my breath 
simultaneously.
A few years later in College I thought about it. and wrote a paper on 
how to drive a Synchro Device with 3phase power on the stator wires. the 
problem is what do you
do with the rotor wire? Well it works out that its a phase shift 180+/- 
from 0 deg or from the non shifted (rotated) leg of the Y or Delta 
Stator Wire.. (pick one)
I will have to look for the paper but  It should be around here some were.
BTW!!! the 400Hz stuff MUST NOT BE CHOPPED ie.. NO DIGITAL STUFF....  so 
get yourself a nice 400Hz 3/phase supply.. or build it.. you can use the 
stuff you
learned about AUDIO amps use push-pull with a center drive... you need 3 
of them and then two (2) phase shifters 1@ 120 deg. #2 @ 240 deg.
BTW they should be less than 1% deviation each. so recap...
1. 400 Hz osc. sine wave gen
2. 120 deg phase shifter
3  240 deg phase shifter
4. three (3) push/pull amps for power
5 a digital controlled phase shifter

tie...
360    deg  1100
180    deg  1011
90      deg  1010
45      deg  1001
12.5   deg  1000
6.25   deg  0111
3.125 deg  0110
1.56   deg  0101
0.78   deg  0100
0.39   deg  0011
0.18   deg  0010
0.09   deg  0001
0000  deg  0000

got it??????

Cris Harrison
BTW we are chopping up a LEAR JET.... Cockpit any takers.. from the 
front of the windows to just in front of the cabin door... pics to follow...

Simon Bennett wrote:

> Since I've got a remote attitude indicator coming in the mail any day 
> now (my first real aircraft instrument), I've been thinking a lot 
> about how to drive it. Almost everyone seems to think driving synchros 
> is an almost impossible task, but I'm not so sure. Trying to generate 
> the signals to control them would definitely be a hell of a challenge, 
> but I'm wondering, wouldn't it be possible, and much less frustrating, 
> to wire the indicator synchro a torque transmitter, the rotor of which 
> is controlled mechanically by a stepping motor or the like? I'd rather 
> not gut the indicator if I can find any way to use it in its original 
> state.
>
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