Given the constraints (2 inputs), a quad op-amp and a 74hc00 or equivalent.
Op-amps turn the low level bipolar sine/cos waves into sufficient amplitude
to drive the 74HC00's which are configured as set/reset latchs.
You bias the op-amps so that the over zero part of the signal sets the latch,
and the under zero part clears it.

Roman Black wrote:
>
> Josh Koffman wrote:
> >
> (regarding rotary encoders for DIAL use)
> > There are ways to use a stepper motor as well, though I've never tried.
> > The ETC Expression lighting console uses just such an arrangement.
>
> I *really* like this idea! :o)
> Having replaced optos (darn unreliable things) in
> so many VCR optical "dial controls" the idea of using
> a $1 surplus stepper motor is brilliant. The detent
> "spring" will never wear out as it is the magnetic
> field of the motor, and with such low currents and
> heating the thing will work for about a zillion years,
> or until the bearings give out. Strong panel mounting,
> all-metal construction, solid bearings, hardened shaft,
> etc etc. Now cheap old-style steppers are available
> everywhere from the junk guys this sounds like a REALLY
> GOOD digital dial.
>
> Now any takers on the simplest circuit to connect one
> to 2 PIC digital inputs?? :o)
> -Roman

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