LSD908 phototransistor - Texas Instruments

LSD908 phototransistor in a "PILL" package by Texas Instruments.

A very small detector as used in many early CNC lathe and milling machine digital readout encoders, soldered directly into the pcb and directly opposed to the led transmitter (TIL23 thru to TIL25), the distance travelled, velocity and direction gained by reading the stripes on an encoder strip, usually 5mm thick glass. (moire fringe effect). Usually set in a group of three. These are minute, the photograph above shows these placed next to a UK. 1 pence coin which is 20mm in diameter. Remember these were manufactured in the days before surface mount components.... much respect to TI.

Awaiting datasheet ( don't hold your breath ! )

We think this is similar to the Optron (Optek) OP600 and Mullard BPX71

Status: NOS (New Old Stock) from 1979

RoHS compliant: no