Difference between tachogenerator and Encoder

-Tachogenerators provide an AC voltage which is proportional to speed just like standard AC generators. The frequency of this waveform, of course, is also proportional to speed. Having a voltage proportional to speed simplifies analog control of a motor.

-Encoders typically provide a series of pulses proportional to rotation or distance. Some encoders provide a binary number representation of rotation or distance where 0001 represents position 1, 0010 represents position 2,

0011 represents position 3, etc. You can calculate system speed by measuring the time between these pulses or positions. Having a set of pulses proportional to distance simplifies digital control of a motor.

Dorian