ON Semiconductor, FOD817B300W DC Input Phototransistor Output Optocoupler, Through Hole, 4-Pin MDIP. Mfr Part No. 5 x ON Semiconductor, FOD852 DC Input Photodarlington Output Optocoupler, 4-Pin. 2 x Toshiba TLP523(F) DC Input Darlington Output Optocoupler Through Hole 4-Pin.
eBay