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<html> <h1>8BIT turntable</h1>

<p>a turntable embedded on a PCB</p>

<p>https://www.youtube.com/watch?v=em2OpwheHMU&amp;</p>

<h2>Layout</h2>

<p><img src=“https://i.imgur.com/jlaOwRV.png” alt=“http://gunook.com/honigbienenzahler-ii/” title=“” /></p>

<h1>encoding</h1>

<h2>gray encoding</h2>

<p>using something like an array of reflective IR sensors </p>

<p><img src=“https://i.imgur.com/KrapStk.png” alt=“qtr-8” title=“” /></p>

<p><strong>components</strong></p>

<ul> <li>QRE111 - <a href=“http://www.onsemi.com/pub/Collateral/QRE1113-D.PDF”>datasheet</a>, <a href=“https://www.aliexpress.com/item/50pcs-lot-QRE1113GR-QRE1113-QRE1113G-SMD4-Original-authentic-and-new-in-stock-Free-Shipping-IC/32841727674.html”>aliExp</a> <img src=“https://i.imgur.com/4fpaVVj.png” alt=“QRE111” title=“” /></li> </ul>

<p><img src=“https://i.imgur.com/5jFBp8g.png” alt=“” title=“” /></p>

<p>a few approaches on the hookup https://cdn.sparkfun.com/datasheets/Sensors/Infrared/SparkFun%20Line%20Follower%20Array_v10.pdf</p>

<p>https://www.pololu.com/docs/0J13/2</p>

<h2>Gray code</h2>

<p>a silkscreen on the round PCB bottom to encode the position using <a href=“http://en.wikipedia.org/wiki/Gray_code”>gray code</a></p>

<p>generator #1 <a href=“http://engineering.olkha.com/gray/”>online</a> generator #2 <a href=“https://github.com/Hyvok/Inkscape-rotary-encoder-disk-generator”>inkscape</a></p>

<p>https://www.youtube.com/watch?v=oc5hIxdCMZ0&amp;</p>

<p>https://www.youtube.com/watch?v=JwU<em>DrI</em>Mmc&amp;</p>

<p>https://www.youtube.com/watch?v=IeWcvAsz88o&amp;</p>

<p>“to get a gray number only change one bit”</p>

<p><img src=“https://d2mxuefqeaa7sj.cloudfront.net/s_C3F26DA1DE2735AB305F4004085FAFE353789C4AD8CC62A80295D78BF90BFD02_1531819410575_image.png” alt=“https://www.quora.com/What-is-the-difference-between-binary-numbers-and-Grays-code” title=“” /></p>

<p><img src=“https://i.imgur.com/DbMB6Vv.png” alt=“https://www.semanticscholar.org/paper/Design-of-absolute-encoder-disk-coding-based-on-n-Paul-Chang/” title=“” /></p>

<h2>DC motor</h2>

<p>simply connecting a dc motor to the spining disk by rotating the disk you convert the enregy to analog input for MCU or whatever problem with this approach it will not give enough output at slow speeds. so probably scratch that.</p>

<h2>Stepper motor</h2>

<p>same as with the DC motor, you connect the motor to the disks center, then hook the stepper winding A1/2,B1/2 to an MCU, you get a nice stepping encoder. </p>

<p>following links are actually to use the sinusoidal wave of the stepper, a bit of a different approach also a problem at low speeds. https://wemakethings.net/2013/02/18/steppers-as-rotary-encoders/ http://www.4qdtec.com/stpen.html</p>

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