[sdiy] Looking for a mini rotary encoder with very low torque (servo type)

[Nathan Trites]

This is the direction I was just thinking, and was also on the Adafruit
site looking at plug and play sensor options.

Jean-Pierre - I'm assuming this is to make the speed on your piano roll
player programmable/repeatable? Is it more important to measure the surface
of the paper itself due to torque/slippage reasons like on a tape machine,
or will measuring the speed of the take up spool get you the same info? If
the latter is an option, what about a magnet and a hall sensor on the take
up spool, disk the same diameter as the take up reel in the drive mechanism
with some other sort of sensor on it like cheater mentioned, or even a
small notch in the take up spool (or equivalent disk in the drive
mechanism) that has a limit switch with roller against it.

If it must be against the paper, opto-interruptors and disks are available
on their own, and then you could rig something up so that assembly rests
lightly against the paper:
https://bc-robotics.com/shop/opto-interrupter-with-mounting-tabs/
https://bc-robotics.com/shop/encoder-disc/

Nathan

On Thu, Dec 12, 2024 at 9:22 AM Gerry Murray via Synth-diy <
synth-diy at synth-diy.org> wrote:

> Hi JP
>
> You could maybe try a resolver. The resolution of them can be very high
> : up to 16 bit.
> https://www.mouser.co.uk/applications/resolver-encoder-motor-control/
> https://www.instructables.com/Arduino-Resolver-Module/
>
> I always like it when you put an inquiry on the list because, usually 6
> months later on, a really cool project emerges. :-)
>
> Best wishes
>
> Gerry
>
>
> On 11/12/2024 15:09, Jean-Pierre Desrochers via Synth-diy wrote:
> > I'm looking for a very small (20mm or less body diameter)
> > rotary encoder with very low torque (servo type).
> > The low torque shaft is needed because it will turn by means
> > of a small wheel with rubber sides that will be put against a moving
> surface, turn and 'follow'
> > the moving surface.. no slipping allowed !
> >
> > The precision of steps/turn is not important.
> > But the higher will be best..
> >
> > I was thinking of using a dismantled PC mouse (rubber ball type)
> > and use one of the two  X/Y optical rotary encoders, but these PC mice
> > nowadays are hard to find.. So.
> >
> > I checked Digikey and Mouser but they have encoder too big
> > for my uses..
> > The smaller I found has 20mm in diameter..
> >
> https://www.digikey.ca/en/products/detail/nidec-components-corporation/RES20D-50-201-1/6469509
> >
> > Any suggestions ?
> >
> >
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