Shaft Encoders

[David Halliday (Volt Computer)]

> -----Original Message-----
> From:	brad.sanders at circellar.com [SMTP:brad.sanders at circellar.com]
> Sent:	Wednesday, April 23, 1997 8:58 PM
> To:	synth-diy at horus.sara.nl
> Subject:	Re: Shaft Encoders
> 
> sasami at blaze.net.au (Ken Stone) was saying...
> 
> >>Im trying to figger out how that would be done with available
> components
> >>w/o using servo encoders.. but those WOULD be really nifty if
> implemented
> >
> >Has anyone ever considered the usee of surplus stepper motors (ex
> flopp or 
> >hard drive) as shaft encoders?
> 
> >The other great shaft encoder to adapt is the arcade video game track
> ball!
> 
> Seems to me the analog "interface" to use stepper motors would be more
> trouble than it's worth - especially when you can buy MICE in quantity
> 10 for like 3 bucks each. One mouse=2 rotary encoders (minus the two
> XOR gates needed to derive the clocks), so figger mebbe four bucks for
> two shaft encoders.
> 
> Besides, all those motors would be HEAVY! Can you imagine even a
> "Mini" with all stepper motor shaft encoders?
> 
> 
> Mice? The nice thing about the motors is that they are ready to use
> without too much modification.  Mice would have to be kit-bashed and
> mechanical support for the encoders fabricated and circuit board made.
> 
> Granted, they do have very nice resolution and are ready to roll - you
> could even design your front panel to use the existing mouse
> circuitry...
> 
> 
> The problem with either of these approaches is deriving absolute
> position. Without further mods you have about ZERO tactile feedback,
> and you have no absolute "zero" setting to allow marking white lines
> on knobs.
> 
> The steppers have a "cogging" sensation when you rotate their shafts -
> would make for a nice feedback.  As for absolute position, this can be
> done through software - reset this control and it is *now* sitting at
> zero.