DC Motors: Encoders

Encoders (Sensors) can be implemented inside the motor or mounted to motor rearside.

They are needed for a precise speed control or angular position control.
Typical application: Printers and scanners.

There are different options:

  • Optical encoders
  • Hall-effect magnetic sensors
  • Resolvers


Beside magnet Hall effect sensors, JE offers a range of optical encoders.

Basic principle is:
A slotted wheel or a black/transparent strip photo print is rotating with the motor shaft.
A photosensor provides a sinewave or pulse pattern, that follows the speed of the motor.

Output signal can be analog (0…3.3Vac) or digital (0…3.3 Vdc or 0…5Vdc).
One signal trace or two signals phase shifted 90° , which enable detection of direction of rotation.

dc motors    dc motors     dc motors 


Several options for resolution.
Terminology: CPR (Counts Per Revolution) and LPI (Lines Per Inch).


HC385MG with slotted encoder wheel
(CPR = 48 ; one signal, sinewave 0…3.3Vac)

   NF123G with fotoprint wheel
(CPR= 32 ; two signals, sinewave 0…3.3Vac)
 dc motors    dc motors