Odd floppy drives (Helitron)

[Brent Hilpert]

> On Sat, 24 Sep 2005, Scott Stevens wrote:
> > The oddest 'floppy' drive that I ever saw was a dictaphone machine that
> > recorded by cutting helical audio tracks like a phonograph record on a
> > thin 'floppy' plastic disk.  Ooops, it wasn't digital (unless you held
> > it in your fingers).
> 

... that would be (or describes) the Gray 'Audograph', made by Northern
Electric (at least in Canada, perhaps by Western Electric in the US).

Circa mid-1940s. The disc is 6.5 in. diameter, holding one reminds one very
much of a bare floppy removed from it's envelope: similar weight (floppiness),
except it's a translucent deep-blue.

(Yes, I do have one (the recorder/player and several blank discs)).


Fred Cisin wrote:
> <nitpick>
> grooves "like a phonograph record" would be "SPIRAL", NOT "helical".
> "Helical" would be like a spiral stair case, or threads on a bolt.
> Some of the early (Edison?) sound recorders DID cut helical threads on the
> outside of a cylinder.
> </nitpick>

Well, the tracking is performed by a helical-thread drive mechanism :)
Actually it's a little unusual in that (in contrast to record players and disc
drives) the head/needle is stationary and the disc is moved 'radially' (as well
as rotating of course).