QSE156/C, QSE157/C, QSE158/C, QSE159/C are plastic silicon photosensors produced by Fairchild Semiconductor Corporation. They have bipolar silicon IC, side-looker, medium wide reception angle, 50°, black epoxy package, matched emitter QEE113/QEE123, daylight filter, high sensitivity, and direct TTL/LSTTL interface.