[sdiy] My Player piano roll project... refining my design

The SynthiMuse synthimuse at gmail.com
Sun Apr 9 23:27:20 CEST 2023


Hi JP

I should have been clearer earlier on so I've attached a scribbled image of
my idea.
There's no need to invert one of the signals. You just need to get nice
linear values from 2 sensors and put them into a differential amplifier.
This will give you a DC value that will tell you the position error and you
can use it to drive the correction mechanism.
Obviously, if the signal from the two sensors are equal, then the paper is
perfectly centred.

I hope this helps.

Best wishes

Gerry


On Sun, 9 Apr 2023, 17:24 Jean-Pierre Desrochers, <jpdesroc at oricom.ca>
wrote:

>
>
> Very good idea.
>
> If I understand correctly their would be 2 sensors close to each other
>
> but set a little apart from each ones. (But on one of the two paper sides
> only)
>
> If so there would be some kind of detected ‘notch’ or ‘peak’
>
> to tell the paper is correctly placed right ?
>
> But when this peak or notch disappears how can I know which direction to
> move the paper
>
> and correct its position ?
>
> I would need the same tandem on the other paper edge.. ?
>
>
>
>
>
>
> ******************************************************************************
>
> De : Synth-diy <mailto:synth-diy-bounces at synth-diy.org> De la part de
> Gerry Murray via Synth-diy
>
> Envoyé : 9 avril 2023 11:20
>
> À : mailto:synth-diy at synth-diy.org
>
> Objet : Re: [sdiy] My Player piano roll project... refining my design
>
>
>
> Hi JP
>
>
>
> I would recommend two of these sensors operated in linear mode, with a
> small difference in their physical position and invert the signal from one
> of them.
>
> From these two signals you would get a 'detent' differential signal that
> would tell you the lateral error and allow you to adjust the horizontal
> position of the paper more accurately.
>
>
>
> Best wishes
>
>
>
> Gerry
>
>
>
> On 09/04/2023 16:09, Jean-Pierre Desrochers wrote:
>
> Hi all again,
>
> I’m still trying to refine my design and working on
>
> the paper centering process circuit.
>
> So far I’m using the tracker bar edge’s holes to detect
>
> left/right paper movements while playing the rolls.
>
> Those who are at the paper’s edge sides.
>
> The system works pretty well
>
> but still some rolls lacks of centering correction.
>
> SO I want to do some tests using Photointerrupters - Slot Type – with open
> collector Outputs.
>
> Like those types:
>
>
>
>
>
> I’m trying to select the best accurate one to detect paper edges
>
> not the overall paper cutting the IR beam..
>
> Any idea of the best specifications to pick one ?
>
>
>
>
>
> De : Synth-diy mailto:synth-diy-bounces at synth-diy.org De la part de
> Jean-Pierre Desrochers
>
> Envoyé : 23 février 2023 17:31
>
> À : mailto:Synth-diy at synth-diy.org
>
> Objet : [sdiy] My Player piano roll project... a small video demo for you..
>
> Importance : Faible
>
>
>
> I’m not done yet with this project but this is promissing..
>
>
>
> https://www.youtube.com/watch?v=K7xXYqCB0AY
>
>
>
> I let the piano roll play its song while filming.. around 4:00 duration.
>
> Enjoy !
>
>
>
>
>
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