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</o:shapelayout></xml><![endif]--></head><body lang=FR-CA link=blue vlink=purple style='word-wrap:break-word'><div class=WordSection1><p class=MsoNormal><o:p> </o:p></p><p class=MsoPlainText><span lang=EN-CA>Winter.. what a good time to work on my electronic projects!<o:p></o:p></span></p><p class=MsoPlainText><span lang=EN-CA>I'm taking the opportunity right now to polish up my old piano roll reader project<o:p></o:p></span></p><p class=MsoPlainText><span lang=EN-CA>for earlier mechanical piano. This project will be able to read the scrolling vintage music paper rolls<o:p></o:p></span></p><p class=MsoPlainText><span lang=EN-CA>containing piano notes and hear them using an external MIDI player.<o:p></o:p></span></p><p class=MsoPlainText><span lang=EN-CA>My prototype takes up a large part of my desktop space,<o:p></o:p></span></p><p class=MsoPlainText><span lang=EN-CA>but it's going well so far.. A big challenge to take up..<o:p></o:p></span></p><p class=MsoPlainText><span lang=EN-CA>From the start I faced 2 problems: First, The IR beams reading strength of each holes<o:p></o:p></span></p><p class=MsoPlainText><span lang=EN-CA>to be read. I managed it using short 2mm ‘light pipes’ between the photo-transistors<o:p></o:p></span></p><p class=MsoPlainText><span lang=EN-CA>and the IR emitting leds to ‘channel’ the light. Second, The SPI parallel to serial<o:p></o:p></span></p><p class=MsoPlainText><span lang=EN-CA>74HC165’s have no Schmitt trigger inputs so… LOTS of jitter readings making the holes readings<o:p></o:p></span></p><p class=MsoPlainText><span lang=EN-CA>Completely unreliable. The solution.. inserting 74HC14 schmitt inverters between<o:p></o:p></span></p><p class=MsoPlainText><span lang=EN-CA>The photo-transistors and the HC165 inputs. Voilà !<o:p></o:p></span></p><p class=MsoPlainText><span lang=EN-CA>Of Note: The bottom photo shows the paper roll installed and ready to play.. <o:p></o:p></span></p><p class=MsoPlainText><span lang=EN-CA>notice the little purple lights above the paper.. <o:p></o:p></span></p><p class=MsoPlainText><span lang=EN-CA>these are infrared LEDs invisible to the naked eye but visible to the camera..<o:p></o:p></span></p><p class=MsoPlainText><span lang=EN-CA><o:p> </o:p></span></p><p class=MsoPlainText><span lang=EN-CA>Have a nice 2023 beginning everybody !<o:p></o:p></span></p><p class=MsoPlainText><span lang=EN-CA>JP<o:p></o:p></span></p><p class=MsoPlainText><span lang=EN-CA><o:p> </o:p></span></p><p class=MsoPlainText><span lang=EN-CA style='mso-ligatures:none'><img width=1123 height=843 style='width:11.6979in;height:8.7812in' id="Image_x0020_1" src="cid:image003.jpg@01D925E3.8ECF3B50"></span><span lang=EN-CA><o:p></o:p></span></p><p class=MsoPlainText><span lang=EN-CA style='mso-ligatures:none'><img width=1123 height=843 style='width:11.6979in;height:8.7812in' id="Image_x0020_2" src="cid:image004.jpg@01D925E3.8ECF3B50"></span><span lang=EN-CA><o:p></o:p></span></p></div></body></html>