Optical encoders

http://www.alibaba.com/product-detail/optical-encoder-sensors_503181569.html

http://xinhsen.en.alibaba.com/product/60388368790-801358871/photo_etching_customized_encoder_disk_for_sensor.html Xinhaisen technology

Suppliers

 * http://www.shijibaike.cn AS5048 around $11 per chip
 * http://www.findchips.cn/search.html?qs=as5145 Request for quote $8
 * http://www.xinhsen.com/index.aspx?language=en optical disks.

AMS

 * https://www.youtube.com/watch?v=DQdHslX-5Lo ,
 * http://ams.com/eng/Products/Position-Sensors/Magnetic-Rotary-Position-Sensors/AS5145H
 * https://www.youtube.com/watch?v=jbcPydrh0aA AS5045 ARDUINO CODE
 * http://ghostgimbals.com/  as5048B 14bit used with AlexMoss Gimbal controller.
 * http://madscientisthut.com/forum_php/viewtopic.php?f=11&t=7 arduino code as5040 . Reading serial bits.
 * http://reprap.org/wiki/Magnetic_Rotary_Encoder_v1.0 as5040 description, code and surface soldering
 * http://www.rottorteam.com/shop/encoders/as5048/ used with Gimbal. Thd AS5048B version uses I2C.
 * http://eu.mouser.com stocks 600 as5048a chips
 * http://www.mouser.com/ds/2/588/ams_AS5048-EK-AB-STM1-341286.pdf design kit 985-AS5048A-EK-AB  for datasheet. Use Dexter diametric magnet part 2910041-1. Diametric means north south poles, 6mm width x 3mm thick.

sindri sebastian

 * http://dangerousprototypes.com/forum/viewtopic.php?f=56&t=3669 Read SPI on rising edge, data latched on falling edge. as5043
 * http://sindri.sebastians-site.de/MagneticRotaryEncoder/Accuracy
 * http://sindri.sebastians-site.de/hg/sindri/file/encoder_release_1.3/firmware/AS5043_tests/ c source
 * http://sindri.sebastians-site.de/hg/sindri/file/encoder_release_1.3/hardware/AS5043-encoder/chasis/lathe Lathe
 * https://www.tindie.com/products/LongHairedHacker/sindri-magnetic-rotary-encoder-1/

dccharacter

 * http://dccharacter.blogspot.com/2012/06/modifying-servo-for-continuous-rotation.html part1, pcb
 * http://dccharacter.blogspot.com/2012/06/modifying-servo-for-continuous-rotation_30.html part2

Belt driven vs gears
With the lathe https://www.youtube.com/watch?v=sC2urdg_bqg belt setup a 25x magnfication factor is achieved(encoder x25 resolution) with much less backlash than planetary gears would have.

as5048
https://github.com/ZoetropeLabs/AS5048A-Arduino, https://github.com/ZoetropeLabs/as5048A-breakout-board

https://github.com/grtyvr/AS5048A-Arduino

https://github.com/crgallac/AS5048A_DUE Used in haptics, sets the correct 4mhz SPI rate.

https://github.com/sosandroid/AMS_AS5048B I2C version

Hall, LVDT

 * http://www.mycockpit.org/forums/showthread.php?t=22267 circle hall sensor with magnets over bearing.
 * http://www.mikesflightdeck.com/lvdts/lvdts.html Linear variable differential transformer.
 * http://www.melexis.com/Hall-Effect-Sensor-ICs/Triaxis%AE-Hall-ICs/MLX90333-648.aspx austria prefered over melexis. Melexis accuracy 0.35 degrees over full rotation, as5045 is 0.05

Quantum devices
https://quantumdevices.wordpress.com/2012/01/26/the-use-of-potentiometers-in-incremental-encoder-design/ Quantum Devices is now proud to introduce it's new line of rotary encoders. Incorporating QDI's patented sensor technology, our QPhase™. Pictures contain https://www.yaskawa.com/pycprd/home chipset. Yaskawa has patents on optical encoders, driving up the price of these devices. See https://patents.google.com/patent/US7348543B2/en. Quantumdevices wordpress blog has various articles on aligning encoders, termination resistors etc.

Manufacturers
http://www.rls.si/ring-encoders

http://ichaus.de/

Abrobotics ebot

 * http://abrobotics.tripod.com/Ebot/using_encoder.htm tutorial code

Drexel
https://www.youtube.com/watch?v=xgIubJHVRwg, http://dasl.mem.drexel.edu/~jiyueHe/rotary_inverted_pendulum/ Rotary inverted pendulum, full code PID on arduino mega.

HEDS 9000

 * https://www.youtube.com/watch?v=T5Xyt7vcOo8 HEDS 9000
 * http://www.bristolwatch.com/arduino/arduino2.htm arduino interrupts

Optical isolators and Robotics

 * http://homepages.which.net/~paul.hills/SpeedControl/Optos.html
 * Robotics engineering http://homepages.which.net/~paul.hills/
 * Embedded systems magazine http://www.embedded.com/
 * http://ocw.mit.edu/index.html
 * Analog and Digital Circuits for Control System Applications: Using the Ti Msp430 Microcontroller
 * p.249 of j.graeme book in journal 'Sensors', optical position sensing.

Links
http://openservo.com/OpenEncoder

http://reprap.org/wiki/MagServo assembly of as5043, soldering, aligning http://letsmakerobots.com/node/18615

http://letsmakerobots.com/node/18470

https://ams.com/chi/content/download/207953/886744

http://www.edn.com/design/sensors/4324812/Speed-acquisition-made-simple

http://www.anaheimautomation.com/manuals/forms/encoder-guide.php