Re: How good a "sine" wave to drive a selsyn/synchro?


"Genome" <ilike_spam@xxxxxxxxxxx> wrote in message
news:p6W_e.4061$9l4.3584@xxxxxxxxxxxxxxxxxxxxxxx
>
> "jtaylor" <jtaylor@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote in message
> news:OuR_e.13362$p5.1689@xxxxxxxxxxxxxxx!nnrp1.uunet.ca...
> > The simplest way to get this pair of devices working in a non-400hz
> 3-phase
> > environment seems to be to program a pic to generate three-phase and
> amplify
> > the output. If I have three pins per phase and run each through a
> resistor
> > of some calculated value I can make a psuedo-sinewave. Is this likely
to
> > have any issues because it's not a true sinewave? This is a hobby-level
> > application, so good enough will be good enough....
> >
> >
>
> If you have three pins per phase then you have nine pins. If you make a
> johnson counter for 6 of the pins and take a weighted sum through the
> resistors then use the seventh bit for polarity then you get something or
> another with two bits to spare. To get your three phases you offset the
> summing resistors for each phase.
>

This sounds good but it's a bit over my head - how will I get the three
phases to vary at 120 degrees?


.

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