[sdiy] damnable digital interface.

[Tim Parkhurst]

Steve,

The "forever spinning knobs" you're talking about are rotary encoders. They
put out two pulse trains when they are turned. The pulses on output "A" will
lead "B" by 90 degrees when the knob is turned one way, and "B" leads "A"
when the knob is turned the other way (referred to as a "Quadrature
Output"). It's fairly easy to get a processor to see which way the knob is
spinning, and to count the pulses. Interfacing one into an existing setup
might be quite a bit of work, however. I'd like to do the same thing with an
old Casio CZ-101 (great box with lots of capabilities, but the interface
really needs a 'data knob' to quickly change parameter values). Anyone know
where to get CZ schematics? If I can figure this out on the CZ, I'll pass
along any info or hints I come up with. I have two CZs, so I guess I can
afford to blow one up. ;)

Tim Servo

-----Original Message-----
From: Steve Begin [mailto:Steve.Begin at pwgsc.gc.ca] 
Sent: Friday, August 02, 2002 11:40 AM
To: Synth (E-mail)
Subject: [sdiy] damnable digital interface.

I'm considering bringing my poly800 out of retirement (and backing it up and
restoring it whenever I need to) but there is one thing I'd love to change
on it and I'm not sure if it's more effort than it's worth.

Is there such a thing as a knob that acts like a membrane switch being
pressed for every x degrees it is turned, and can close another switch when
it's turned the other way?  I've seen volume controls on digital amplifiers
with knobs that can spin forever and seem like maybe that is how they
function, but I'm not really sure.

It's a bit annoying having to press up 80 times consecutively when adjusting
the cutoff frequency :)


> Steve Begin
> Technical Support
> PDP III 7C2-21
> (819) 956-0458
> 
> 



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