This simple and affordable quadrature-output encoder fits onto the rear shaft of a motor so its position and velocity can be monitored.
There are so many projects that require motor position control that Phidgets decided to make an inexpensive, reliable option. The ENC4109 is exactly that: an affordable optical quadrature encoder that is compatible with the mounting pattern of the majority of the DC and stepper motors sold here (the same mounting pattern as the higher precision 3531_0 Optical Rotary Encoder HKT22).
