[sdiy] rotary encoders

[Tom Arnold]

On Fri, Dec 10, 2004 at 04:33:39PM +0100, ChristianH wrote:
> Well, what about misusing the "stepper motor controller", and letting
> the motor move the knob? Then you wouldn't need any LEDs at all...

How would you get visual feedback?  A motorized slider is great because you
get visual feedback, and motorized volume controls on stereos are fine
because again, its a 300degree span of rotation with a pointer, so lots of
feedback.  Having a motor spin itself with a faceless black knob wouldnt be
so usefull.

Google search term "Stepper motor as rotary encoder"
This page is decent : http://www.webx.dk/oz2cpu/20m/encoder.htm

The big advantage I found when playing with one was the mass.  With a good
sized knob on a large motor you get great tactile feel.  Go ahead and make
it 10 turns "virtual stop to virtual stop" cause you can just give the knob
a good hard spin and let it wind its way out there for you.  The LED ring
around the motor was using tri-color LEDs and faded through the rainbow as
you went up and down the scale ( 1 color per octave, 12 LEDs in the ring ).

Stepper motors that work nicely are $1-$5ea from a variety of sources.  I'm
a big fan of Herbach&Rademan for this sort of surplus.  Quite a few of the
motors ( like the ones in 5.25" floppy drives ) have nice 1/4" shafts too.

I still have the panel I made in storage with 16 stepper motors mounted on
it for the sequencer.  Completed I think it would give a CS80 a good run for
its money weight-wise.

-- 
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 - Tom Arnold       -  Free Synth DIY webspace http://www.sdiy.org 
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