Isocom isp817 series optoisolators 1 channel 4 pin isocom isp817bx this optically coupled isolator has a current transfer ratio of 130 to 260 and is suitable for high density pcb mounting it utilises an ir led and npn silicon phototransistor to give a device with high isolation value and high current transfer ratio suitable for applications such as logic to logic isolators line receivers current level sensors ac to ttl conversion etc isocom isp817bx optoisolator 1 channel 130 260 ctr