[sdiy] Reading holes (voids) on piano paper rolls.. using Photo-transistors and PIC micro..

[Jean-Pierre Desrochers]

Sorry for the big delay to reply Roman..
About the piano reader project,  I hadn't thought about putting the opto-transistors
right inside the short copper pipes that are each welded behind each small square holes
instead of putting fiber optics there to carry the IR light from the holes to the IR transistors..
And yes maybe the 'diffused' IR in the small pipes would get rid of the dotted type lines
and read them as a continuous one..
I'll try that suggestion.. Very clever !

And about the IR transmitters.. Well indeed a heated wire will let the surrounding
light appear to the holes and mess things up.
This will need a thick PCB (around 3mm thick) with a size of around 300mm x 10mm.

When I'm ok I'll do some test on that..
Many Thanks !

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> -----Message d'origine-----
> De : Roman Sowa <modular at go2.pl>
> Envoyé : 13 novembre 2022 06:29
> À : Jean-Pierre Desrochers <jpdesroc at oricom.ca>; Synth-diy at synth-diy.org
> Objet : Re: [sdiy] Reading holes (voids) on piano paper rolls.. using Photo-
> transistors and PIC micro..
> 
> One thin heated wire in front of the holes would indeed be most elegant
> solution, but I'm also not sure if those wavelengths are in range of
> optotransistor sensing. And what is more important, such solution would not
> block ambient light in any way, so you could play it from the distance with a
> flashlight :)
> 
> It's no problem for JLC to make 5mm wide long PCB filled with SMD IR LEDs,
> and IMHO it is cute. Maybe even 5mm will be too narrow to block ambient
> light, so maybe more like 10mm sounds like good choice. And on the back
> side you can put some art-deco graphics to match the aesthetics of entire
> instrument.
> 
> Roman
> 
> W dniu 2022-11-11 o 15:58, Jean-Pierre Desrochers pisze:
> 
> (...)
> > I was thinking of something else that could work..
> >
> > Heat is Infrared so.. Using a heating element wire over all the brass
> > bar holes could be seen as a LEDS array but smaller in width (no PCB).
> > This wire just heated a little could be glued in a plexiglass
> > transparent Bar placed over the brass reading bar.??
> > Or use some kind of diffused incandescent light all over the scrolling
> > paper that has infrared specs close to 940nm.. ?
> >
> > But I’m about sure heating wire spectral wavelength would be far from
> > my needed 940nm..
> >
> > Hmmm…
> >
> >