<html xmlns:v="urn:schemas-microsoft-com:vml" xmlns:o="urn:schemas-microsoft-com:office:office" xmlns:w="urn:schemas-microsoft-com:office:word" xmlns:m="http://schemas.microsoft.com/office/2004/12/omml" xmlns="http://www.w3.org/TR/REC-html40"><head><meta http-equiv=Content-Type content="text/html; charset=utf-8"><meta name=Generator content="Microsoft Word 15 (filtered medium)"><style><!--
/* Font Definitions */
@font-face
{font-family:"Cambria Math";
panose-1:2 4 5 3 5 4 6 3 2 4;}
@font-face
{font-family:Calibri;
panose-1:2 15 5 2 2 2 4 3 2 4;}
/* Style Definitions */
a:link, span.MsoHyperlink
{mso-style-priority:99;
color:blue;
text-decoration:underline;}
p.MsoPlainText, li.MsoPlainText, div.MsoPlainText
{mso-style-priority:99;
mso-style-link:"Texte brut Car";
margin:0cm;
font-size:11.0pt;
font-family:"Calibri",sans-serif;
mso-ligatures:standardcontextual;
mso-fareast-language:EN-US;}
span.TextebrutCar
{mso-style-name:"Texte brut Car";
mso-style-priority:99;
mso-style-link:"Texte brut";
font-family:"Calibri",sans-serif;}
span.EmailStyle21
{mso-style-type:personal-reply;
font-family:"Calibri",sans-serif;
color:windowtext;}
.MsoChpDefault
{mso-style-type:export-only;
font-size:10.0pt;}
@page WordSection1
{size:612.0pt 792.0pt;
margin:70.85pt 129.75pt 70.85pt 129.7pt;}
div.WordSection1
{page:WordSection1;}
--></style><!--[if gte mso 9]><xml>
<o:shapedefaults v:ext="edit" spidmax="1026" />
</xml><![endif]--><!--[if gte mso 9]><xml>
<o:shapelayout v:ext="edit">
<o:idmap v:ext="edit" data="1" />
</o:shapelayout></xml><![endif]--></head><body lang=FR-CA link=blue vlink=purple style='word-wrap:break-word'><div class=WordSection1><p class=MsoPlainText>Here is the thing,<o:p></o:p></p><p class=MsoPlainText><o:p> </o:p></p><p class=MsoPlainText><span lang=EN-CA>These old paper rolls have always had tendencies to 'undulate' over time..<o:p></o:p></span></p><p class=MsoPlainText style='margin-bottom:12.0pt'><span lang=EN-CA>I mean even if you align the paper let's say to the left from a known<br>paper hole position with the corresponding tracker bar hole<br>after a short while the paper alignment will slowly drift left or right<br>and you'll lose your 'alignment' and start loosing notes appearing<br>on the paper roll. So you cannot align then 'forget' what will happen.<o:p></o:p></span></p><p class=MsoPlainText><b><span lang=EN-CA>But I found a very easy way to stabilize the paper position<br>all over the paper length.<o:p></o:p></span></b></p><p class=MsoPlainText><span lang=EN-CA><o:p> </o:p></span></p><p class=MsoPlainText><span lang=EN-CA>But first let me describe my path so far..<o:p></o:p></span></p><p class=MsoPlainText><span lang=EN-CA>My first attempts were to read the paper's far left/right edges<o:p></o:p></span></p><p class=MsoPlainText><span lang=EN-CA>Using the tracker bar holes there for this purpose..<o:p></o:p></span></p><p class=MsoPlainText><span lang=EN-CA>2 to the left and 2 to the right.<o:p></o:p></span></p><p class=MsoPlainText><span lang=EN-CA>Well this approach worked very well for the original pneumatics <o:p></o:p></span></p><p class=MsoPlainText><span lang=EN-CA>auto stabilisation. But using these 4 holes with optic sensors<o:p></o:p></span></p><p class=MsoPlainText><span lang=EN-CA>didn't work very well.. Here is why:<o:p></o:p></span></p><p class=MsoPlainText><span lang=EN-CA>The 4 holes pneumatics workings were pretty 'forgiving' and tolerant<br>for any varying paper width, undulations and thickness (no paper crossing optics back then)<br>but could nevertheless detect any changes in the paper alignment<br>and act upon. Using optical sensors needed them to be at very precise<br>positions within the tracker bar to produce the same fast results<br>as the pneumatics. <o:p></o:p></span></p><p class=MsoPlainText><span lang=EN-CA>And that assuming the paper rolls width are ALL exactly the same<br>which is not the case.<o:p></o:p></span></p><p class=MsoPlainText><span lang=EN-CA><br><b>Working Solution:<o:p></o:p></b></span></p><p class=MsoPlainText><b><span lang=EN-CA><o:p> </o:p></span></b></p><p class=MsoPlainText><span lang=EN-CA>So.. Instead of checking BOTH left and right sides of the paper<br>why not use only one sensor.. let’s say one of the two far left ones.<o:p></o:p></span></p><p class=MsoPlainText><span lang=EN-CA>And check the HI or LOW state of it while the paper roll is playing<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> Transition zone<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> HI, No IR beam so | LOW, IR beam passing so<o:p></o:p></span></p><p class=MsoPlainText><span lang=EN-CA> Paper over sensor | edge too far right that let beam pass<o:p></o:p></span></p><p class=MsoPlainText><span lang=EN-CA> Push paper to the right | Push the paper to the left<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><o:p> </o:p></span></p><p class=MsoPlainText><span lang=EN-CA>The thing here is to try to keep the paper at the ‘transition’ zone<br>which is impossible -> but this keeps the centering motor working<br>all the time (almost.. since there is a slight delay between each changes)<br>and keep the paper aligned <u>within less than 1mm precision !!!<br></u><b>Please note each paper holes have around 2mm in width so alignment is paramount !<br></b>Two sensors would not give this precision (unless there is a more elaborate design around them)<br>The only thing I have to do now is to adjust the ‘offset’ screw<br>at the left of the roll mechanism to align the paper holes<br>with the tracker holes just before playing the roll. That’s all.<br>But this time there is an auto-alignment working afterward !<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>Using this method shrunk a lot the centering software<o:p></o:p></span></p><p class=MsoPlainText><u><span lang=EN-CA>and saved me around 15 piano rolls that were unreadable<br>and more ‘undulated’ and difficult to read than all the rest of rolls I had..<br></span></u><span lang=EN-CA>These rolls were almost ready for dumpster.. <br>But using this easy technics I can now read them and saved them.<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>Too long email but explanations are always worthwhile.<o:p></o:p></span></p><p class=MsoPlainText><span lang=EN-CA>Jean-Pierre<u><o:p></o:p></u></span></p><p class=MsoPlainText><span lang=EN-CA><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><o:p> </o:p></span></p><p class=MsoPlainText><span lang=EN-CA><o:p> </o:p></span></p><p class=MsoPlainText>> <span lang=FR style='mso-fareast-language:FR-CA'>-----Message d'origine-----</span><o:p></o:p></p><p class=MsoPlainText>> <span lang=FR style='mso-fareast-language:FR-CA'>De : Roman Sowa <<a href="mailto:modular@go2.pl">modular@go2.pl</a>></span><o:p></o:p></p><p class=MsoPlainText>> <span lang=FR style='mso-fareast-language:FR-CA'>Envoyé : 11 avril 2023 06:17</span><o:p></o:p></p><p class=MsoPlainText>> <span lang=FR style='mso-fareast-language:FR-CA'>À : Jean-Pierre Desrochers <<a href="mailto:jpdesroc@oricom.ca">jpdesroc@oricom.ca</a>>; <a href="mailto:Synth-diy@synth-diy.org">Synth-diy@synth-diy.org</a></span><o:p></o:p></p><p class=MsoPlainText>> <span lang=FR style='mso-fareast-language:FR-CA'>Objet : Re: [sdiy] My Player piano roll project... refining my design</span><o:p></o:p></p><p class=MsoPlainText>> <o:p></o:p></p><p class=MsoPlainText>> How precise are all rolls ever made? I mean I find it hard to believe that paper<o:p></o:p></p><p class=MsoPlainText>> rolls made 100 years ago were so precisely made that paper edge was in +/-<o:p></o:p></p><p class=MsoPlainText>> 0.1mm tolerance distance from the lowest or top note hole. What I'm saying is<o:p></o:p></p><p class=MsoPlainText>> that maybe it's better to adjust paper position based on actual note sensors,<o:p></o:p></p><p class=MsoPlainText>> and don't really care about the edges?<o:p></o:p></p><p class=MsoPlainText>> OTOH it might be too complex, because you'd have to monitor the amplitudes<o:p></o:p></p><p class=MsoPlainText>> of all sensors, multiplying circuits complexity a few times.<o:p></o:p></p><p class=MsoPlainText>> <o:p></o:p></p><p class=MsoPlainText>> As for paper edge location stability, I like Gerry's idea, it's the way to do it, but<o:p></o:p></p><p class=MsoPlainText>> you may also go one step further, and use linear scanning sensor, the kind<o:p></o:p></p><p class=MsoPlainText>> used in flatbed scanners, or industrial positioning systems. This will give you<o:p></o:p></p><p class=MsoPlainText>> wide range of exact location info.<o:p></o:p></p><p class=MsoPlainText>> You could even make simplified linear scanner on your own, just put a bunch<o:p></o:p></p><p class=MsoPlainText>> of small phototransistors side by side, read them all by ADC and calculate<o:p></o:p></p><p class=MsoPlainText>> measured paper edge location in the micro controlling stepper motors.<o:p></o:p></p><p class=MsoPlainText>> <o:p></o:p></p><p class=MsoPlainText>> Roman<o:p></o:p></p><p class=MsoPlainText>> <o:p></o:p></p><p class=MsoPlainText>> W dniu 2023-04-09 o 17:09, Jean-Pierre Desrochers pisze:<o:p></o:p></p><p class=MsoPlainText>> > Hi all again,<o:p></o:p></p><p class=MsoPlainText>> ><o:p></o:p></p><p class=MsoPlainText>> > I’m still trying to refine my design and working on<o:p></o:p></p><p class=MsoPlainText>> > the paper centering process circuit.<o:p></o:p></p><p class=MsoPlainText>> ><o:p></o:p></p><p class=MsoPlainText>> > So far I’m using the tracker bar edge’s holes to detect<o:p></o:p></p><p class=MsoPlainText>> > left/right paper movements while playing the rolls.<o:p></o:p></p><p class=MsoPlainText>> > Those who are at the paper’s edge sides.<o:p></o:p></p><p class=MsoPlainText>> > The system works pretty well<o:p></o:p></p><p class=MsoPlainText>> ><o:p></o:p></p><p class=MsoPlainText>> > but still some rolls lacks of centering correction.<o:p></o:p></p><p class=MsoPlainText>> > SO I want to do some tests using Photointerrupters - Slot Type – with<o:p></o:p></p><p class=MsoPlainText>> > open collector Outputs.<o:p></o:p></p><p class=MsoPlainText>> > Like those types:<o:p></o:p></p><p class=MsoPlainText>> ><o:p></o:p></p><p class=MsoPlainText>> > I’m trying to select the best accurate one to detect _paper edges_<o:p></o:p></p><p class=MsoPlainText>> > not the overall paper cutting the IR beam..<o:p></o:p></p><p class=MsoPlainText>> > Any idea of the best specifications to pick one ?<o:p></o:p></p><p class=MsoPlainText>> ><o:p></o:p></p><p class=MsoPlainText>> > *De :*Synth-diy <<a href="mailto:synth-diy-bounces@synth-diy.org"><span style='color:windowtext;text-decoration:none'>synth-diy-bounces@synth-diy.org</span></a>> *De la part de*<o:p></o:p></p><p class=MsoPlainText>> > Jean-Pierre Desrochers<o:p></o:p></p><p class=MsoPlainText>> > *Envoyé :* 23 février 2023 17:31<o:p></o:p></p><p class=MsoPlainText>> > *À :* <a href="mailto:Synth-diy@synth-diy.org"><span style='color:windowtext;text-decoration:none'>Synth-diy@synth-diy.org</span></a><o:p></o:p></p><p class=MsoPlainText>> > *Objet :* [sdiy] My Player piano roll project... a small video demo for<o:p></o:p></p><p class=MsoPlainText>> > you..<o:p></o:p></p><p class=MsoPlainText>> > *Importance :* Faible<o:p></o:p></p><p class=MsoPlainText>> ><o:p></o:p></p><p class=MsoPlainText>> > I’m not done yet with this project but this is promissing..<o:p></o:p></p><p class=MsoPlainText>> ><o:p></o:p></p><p class=MsoPlainText>> > <a href="https://www.youtube.com/watch?v=K7xXYqCB0AY"><span style='color:windowtext;text-decoration:none'>https://www.youtube.com/watch?v=K7xXYqCB0AY</span></a><o:p></o:p></p><p class=MsoPlainText>> > <<a href="https://www.youtube.com/watch?v=K7xXYqCB0AY"><span style='color:windowtext;text-decoration:none'>https://www.youtube.com/watch?v=K7xXYqCB0AY</span></a>><o:p></o:p></p><p class=MsoPlainText>> ><o:p></o:p></p><p class=MsoPlainText>> > I let the piano roll play its song while filming.. around 4:00 duration.<o:p></o:p></p><p class=MsoPlainText>> ><o:p></o:p></p><p class=MsoPlainText>> > Enjoy !<o:p></o:p></p><p class=MsoPlainText>> ><o:p></o:p></p><p class=MsoPlainText>> ><o:p></o:p></p><p class=MsoPlainText>> > _______________________________________________<o:p></o:p></p><p class=MsoPlainText>> > Synth-diy mailing list<o:p></o:p></p><p class=MsoPlainText>> > <a href="mailto:Synth-diy@synth-diy.org"><span style='color:windowtext;text-decoration:none'>Synth-diy@synth-diy.org</span></a><o:p></o:p></p><p class=MsoPlainText>> > <a href="http://synth-diy.org/mailman/listinfo/synth-diy"><span style='color:windowtext;text-decoration:none'>http://synth-diy.org/mailman/listinfo/synth-diy</span></a><o:p></o:p></p><p class=MsoPlainText>> > Selling or trading? Use <a href="mailto:marketplace@synth-diy.org"><span style='color:windowtext;text-decoration:none'>marketplace@synth-diy.org</span></a><o:p></o:p></p></div></body></html>