Two new phototransistors from Hamamatsu Corp., the S10084 and S10115, are available for use in brightness-detection applications such as backlight control of LCD TVs and mobile devices, ambient light sensing in household or outdoor lighting fixtures, and light detection in surveillance cameras. The S10084 is a through-hole-type phototransistor that can be easily implemented as a replacement for CdS photoconductive cells of the same shape, to comply with RoHS directives. The S10115 is a surface-mounted phototransistor with miniature dimensions (1.25 mm x 2.0 mm x 0.8 mm). Both have a spectral response range of 380 to 750 nm, which closely matches the spectral sensitivity of the human eye. Peak sensitivity is 550 nm. The S10115 can serve as an economical replacement to CdS photoconductive cells.