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[[Image:Odometergearcropped.jpg|thumb|[[Hall effect]] quadrature encoder, sensing gear teeth on the [[driveshaft]] of a robot vehicle.]]
* '''Mechanical''': Also known as conductive encoders. A series of circumferential copper tracks etched onto a PCB is used to encode the information via contact brushes sensing the conductive areas. Mechanical encoders are economical but susceptible to mechanical wear. They are common in human interfaces such as [[digital multimeter]]s.<ref>{{cite web |url=https://www.digikey.com/en/articles/techzone/2012/apr/a-designers-guide-to-encoders |title=A Designer's Guide to Encoders |website=digikey.com |date=19 April 2012 |access-date=23 November 2019}}</ref>
* '''Optical''': This uses a light shining onto a [[photodiode]] through slits in a
* '''On-Axis Magnetic''': This technology typically uses a specially magnetized 2 pole neodymium magnet attached to the motor shaft. Because it can be fixed to the end of the shaft, it can work with motors that only have 1 shaft extending out of the motor body. The accuracy can vary from a few degrees to under 1 degree. Resolutions can be as low as 1 degree or as high as 0.09 degree (4000 CPR, Count per Revolution).<ref>{{cite web |url=http://massmind.ecomorder.com/techref/io/sensor/pos/enc/ENC2.htm |title=MassMind Magnetic High Speed Non-Contact Quadrature Encoder V2 |website=MassMind.org |date=10 January 2018 |access-date=12 July 2019}}</ref> Poorly designed internal interpolation can cause output jitter, but this can be overcome with internal sample averaging.
* '''Off-Axis Magnetic''': This technology typically employs the use of rubber bonded ferrite magnets attached to a metal hub. This offers flexibility in design and low cost for custom applications. Due to the flexibility in many off axis encoder chips they can be programmed to accept any number of pole widths so the chip can be placed in any position required for the application. Magnetic encoders operate in harsh environments where optical encoders would fail to work.
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Inexpensive incremental encoders are used in [[computer mouse#Mechanical mice|mechanical computer mice]]. Typically, two encoders are used: one to sense left-right motion and another to sense forward-backward motion.
===Rotary (Angle) Pulse Encoder===
[[File:Rotary Pulse Encoder Operation & Teardown.jpg|thumb|Rotary (Angle) Pulse Encoder Operation & Teardown]]
A Rotary (Angle) Pulse Encoder has a SPDT switch for each direction, with each one only operating in the direction of travel. Each turn indent in one direction causes the SPDT switch associated with that direction only to toggle.
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== External links ==
{{Commons category|Rotary encoders}}
* [http://smallformfactors.mil-embedded.com/article-id/?3039= "Choosing a code wheel: A detailed look at how encoders work"] {{Webarchive|url=https://web.archive.org/web/20220522143245/http://smallformfactors.mil-embedded.com/article-id/?3039= |date=2022-05-22 }} article by Steve Trahey 2008-03-25 describes "rotary encoders".
* [https://www.embedded.com/encoders-provide-a-sense-of-place/ "Encoders provide a sense of place"] article by Jack Ganssle 2005-07-19 describes "nonlinear encoders".
* [http://www.societyofrobots.com/sensors_encoder.shtml "Robot Encoders"].
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