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

[Roman Sowa]

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…
>
>