The EL303x, EL304x, EL306x and EL308x series devices consist of a GaAs infrared emitting diode optically coupled to a monolithic silicon a zero voltage crossing photo triac. They are designed for use with a discrete power triac in the interface of logic systems to equipment powered from 110 to 240 VAC lines, such as solid-state relays, industrial controls, motors, solenoids and consumer appliances, etc.