Take a minute to browse Circuit Specialists' array of affordable infrared LEDs and phototransistors. Our RoHS-compliant infrared emitting diodes are made with gallium arsenide and are mechanically and spectrally matched to the phototransistor. Infrared phototransistors are incredibly bright and reliable and consume very little energy. We also carry cadmium sulfide (CdS) photocells with variable resistance — high resistance in darkness and low resistance when illuminated. Save more when you buy in bulk.