It does sound like the Eyetech EZ-DF0. That allowed PC drives to be plugged on to the standard floppy interface, but only works if it is plugged on the right way. Have a very close look at it to see if it is marked to show which way it should go. Oh, yea, I did plug mine the wrong way first and it didn't work until I turned it around ;-)
Otherwise, send a photo and I'm sure someone will be able to identify it :-)
