Ah, H11AV, I couldn't tell what the H was.
Datasheet is here:
http://pdf1.alldatasheet.com/datasheet-pdf/view/52725/FAIRCHILD/H11AV1.html
Most of the variations you see are likely package and lead styles, temperature ranges, or the sort of packaging the parts come in. There are often slightly different part numbers for parts that ship loose in IC tubes, cut tape, bandoliers for automated assembly, etc.
Looking over that datasheet, the most relevant item is the 70V C-E rating and the fact that it's a phototransistor output. Looks like the CNY17F series would be a good match.
http://www.fairchildsemi.com/ds/CN/CNY172M.pdf
It's worth checking whether the Base of the phototransistor (pin 6) is connected to anything. Usually it isn't and many/most transistor output optoisolators don't connect it internally but if it is used then you'll want to get a part that has it.
You can test the optoisolator fairly easily. Connect a voltage source of perhaps 5-20V through a 10k or so resistor to the collector and connect the emitter to ground. Wire the LED up through about a 470 Ohm resistor to a source of 5V and then measure from the C-E pins with a voltmeter. The voltage should drop to a fraction of a Volt with the LED powered, and rise to the supply voltage without the LED connected.
Datasheet is here:
http://pdf1.alldatasheet.com/datasheet-pdf/view/52725/FAIRCHILD/H11AV1.html
Most of the variations you see are likely package and lead styles, temperature ranges, or the sort of packaging the parts come in. There are often slightly different part numbers for parts that ship loose in IC tubes, cut tape, bandoliers for automated assembly, etc.
Looking over that datasheet, the most relevant item is the 70V C-E rating and the fact that it's a phototransistor output. Looks like the CNY17F series would be a good match.
http://www.fairchildsemi.com/ds/CN/CNY172M.pdf
It's worth checking whether the Base of the phototransistor (pin 6) is connected to anything. Usually it isn't and many/most transistor output optoisolators don't connect it internally but if it is used then you'll want to get a part that has it.
You can test the optoisolator fairly easily. Connect a voltage source of perhaps 5-20V through a 10k or so resistor to the collector and connect the emitter to ground. Wire the LED up through about a 470 Ohm resistor to a source of 5V and then measure from the C-E pins with a voltmeter. The voltage should drop to a fraction of a Volt with the LED powered, and rise to the supply voltage without the LED connected.