I thought you were confused about the level difference between PC floppy
drives and Apple floppy drives--and you are.
No "cable" can convert the Apple floppy interface to a standard floppy
interface.
In 1982, I converted two standard SA400's to be Disk ][ compatible. It
involved about six pages (single-spaced) of wiring changes to the
digital/analog board in the drive. I recall spending about three hours
modifying each board--lots of wire and solder!
The net effect of the extensive modifications was to disable virtually all
of the digital controller on the board, directly exposing the head stepper
motor phases and directly connecting to the write signal and the detected
head read signal.
Since the SA400 boards were built entirely of MSI TTL chips, all nodes of
the circuit were available for modification. Modern (!) floppy drives have
many fewer chips with higher integration levels, so it is unlikely that
such a modification would still be possible.
-michael - NadaNet 3.1 and AppleCrate II: http://home.comcast.net/~mjmahon