Sensata - BEI Sensors 01002-8683 Encoder, Incremental, Optical, 5-28VDC, 3/8" Shaft, 3600 Cycles/turn, 2 Channel Overview BEI Model H25 Incremental Encoders H25 Incremental Optical Encoders are the flagship of the BEI Sensors product line. Designed from the ground up, they provide instantaneous information on the position of a rotating shaft by producing one square wave cycle per increment..