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.

Hack your servo

 * http://www.01mechatronics.com/ he 01TM Supermodified controller is so small that it can replace electronics of any standard size RC servo, transforming it to a highly accurate actuator. Our magnetic absolute encoder can be integrated at the back end of ANY DC motor! SmCo magnet ensures high fidelity at high temperatures. Many interfaces available. NY DC motor01TM Mechatronics holds a patend for integrating the Supermodified controller at the back end of ANY DC motor. By combining rapid prototyping and machining a seamless integration is achieved for any geometry. The world's tiniest motor control solution is here- At 16x16x12mm and 8 grams, Includes absolute encoder with 32768 ticks  revolution, - Can operate up to 24V, 5A .  see https://humerusrobot.com/,  humerus bot video
 * http://www.robotshop.com/letsmakerobots/hack-your-servo-v300-get-full-pid-position-and-speed-control-your-hobby-servo
 * http://www.01mechatronics.com/product/supermodified-v30-rc-servos The 01TM Supermodified for RC-servos is a complete motion control module that consists of a DC motor controller and encoder. Overall dimensions are 16x16x12mm (without the sensor shaft). It is designed to replace the electronics of an RC-servo, transforming it to a fully enclosed motion control module with very high accuracy (0,011o) and digital interface with daisy-chain capability. Backlash of the RC-servo is not an issue because the encoder senses the angle of the gearbox output shaft. The motor controller implements position and velocity profiles that are recalculated with every received setpoint. The communication protocol has been developed by 01TM Mechatronics and provides exceptional functionality. For example it provides synchronized control of all motors on the bus or control of two motors as if they were one etc. The module can be controlled by a PC or an embedded platform. APIs for popular software and embedded platforms are available for free and can be downloaded from our site.  There is also a standalone application for this purpose. The 01TM Supermodified for RC-servos implemented interfaces include Matlab, Microsoft .Net, Arduino. Development of a LabView interface is under way. supermodified servo controller video
 * http://www.instructables.com/id/Laser-Painting/step4/01-Mechatronics-Super-Modified-Servo/
 * https://github.com/Biomimetix/SuperModified_Servo
 * https://github.com/sushihangover/SupermodifiedServo forked to github from google code preferred fork, eagle files.
 * https://github.com/zisi/SuperModifiedServo-ROS ROS implementation


 * http://web.archive.org/web/20110302063341/http://www.01mech.com/supermodified ,
 * https://groups.google.com/forum/#!forum/dorkbotpdx-blabber
 * https://github.com/jandetlefsen/Supermodified-Servo Modified serveo with as5145 magnetometer

Links
Cnc Homofaciens hand tools made cnc,angle iron, threading etc. using crude DIY Optical encoders.

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