a turntable embedded on a PCB, a silkscreen on a round PCB to encode the position using [[#gray_code]]

{{:video-1547726867.mp4}} {{youtube>em2OpwheHMU?medium}} {{:20190208_151040.mp4|}} {{::turntablepcb-v4-zofzpcb.mp4|using www.zofzpcb.com on archLinux/wine}}
{{:v1.3.jpg?400}} {{:50533102_325584924718706_62649425226366976_n.jpg?400}}

[[https://github.com/idiot-io/turntablePCB|github]] repository


=== tools used ===

[[https://inkscape.org|inkscape]]\\
extensions
     *[[https://github.com/badgeek/svg2shenzhen|svg2shenzhen]]
     *[[https://github.com/Hyvok/Inkscape-rotary-encoder-disk-generator|rotary encoder generator]] 

[[https://kicad.org|kicad]]
  *[[https://github.com/idiot-io/turntablePCB/blob/master/board/kicad_gerber_gen.py|python script example to create plot files to build a board]]

===Layout===
[[https://www.pololu.com/docs/0J13/2|digital]] \\
{{:pasted:20190122-211551.png}}

[[https://www.pololu.com/docs/0J13/3|analog]] \\
{{:pasted:20190601-085501.png}}


a few guides and approaches

  *[[http://gunook.com/honigbienenzahler-ii|Honey bee counter II]]
  *https://cdn.sparkfun.com/datasheets/Sensors/Infrared/SparkFun%20Line%20Follower%20Array_v10.pdf


===Gray code===
 [[http://en.wikipedia.org/wiki/Gray_code|wikipedia]]\\

<blockquote>{{youtube>IeWcvAsz88o?medium}}
<cite>"to get a gray number only change one bit"</cite>
</blockquote>

<blockquote>{{:pasted:20190122-192340.png}}
<cite>http://datagenetics.com/blog/november32014/</cite>
</blockquote>

{{:greycode.png}} {{https://i.imgur.com/DbMB6Vvm.png}}


===components===
  *QRE1113 - [[http://www.onsemi.com/pub/Collateral/QRE1113-D.PDF|datasheet]], [[https://www.aliexpress.com/item/50pcs-lot-QRE1113GR-QRE1113-QRE1113G-SMD4-Original-authentic-and-new-in-stock-Free-Shipping-IC/32841727674.html|aliExp]]
{{https://i.imgur.com/oE29h9I.png}} {{https://i.imgur.com/82dWTnM.png}} \\
{{https://i.imgur.com/4fpaVVjl.png}} {{https://i.imgur.com/5jFBp8gl.png}}


====other methods====
the following are for reference
===LED as light Sensor===
no word regarding detection speed
  *[[https://wiki.analog.com/university/courses/electronics/electronics-lab-led-sensor|analog.com]]
  *[[https://makezine.com/projects/make-36-boards/how-to-use-leds-to-detect-light/|makezine]]

===magnetic===
[[http://www.ichaus.de/upload/pdf/WP6en_Magnetic_vs_optical_17092012.pdf|Magnetic_vs_optical]]

===DC motor===
simply connecting a dc motor to the spinning disk\\
by rotating the disk you convert the energy to analog input for MCU or whatever\\
problem with this approach it will not give enough output at slow speeds. so probably scratch that.

===Stepper motor===

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.

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/|steppers-as-rotary-encoders]]
  * [[http://www.4qdtec.com/stpen.html|stpen]]