TEPT5700 - 

TEPT Series Ambient Phototransistors
The TEPT series, from Vishay Semiconductor, are a family of ambient light sensors. They are available in either 3mm (T-1) or 5mm (T-1 3/4) through-hole packages. These NPN epitaxial planar phototransistors have a clear plastic package and are sensitive to visible light, similar to the human eye. Suitable applications for the TEPT series include ambient light sensors or replacement CdS photoresistors.