[sdiy] Scavenging the electronics graveyard

[Rainer Buchty]

On Mon, 22 Oct 2007, JH. wrote:
>
> >I have always wanted to make some sort of analog delay using a floppy disk 
> >drive! Never gotten around to that though...
> 
> Or something like a Mellotron!

Neat idea. Although polyphony would be impossible with a single disk, 
that very disk could in theory store up to 160 (well, 164, if you go to 
the limits -- after all, the Atari ST had superformatters up to 82 
tracks) keys.

Would of course require an adapted motor control to adjust the rotation 
to track length.

Or a polyphonic machine, one drive per key and 128 velocity settings...

Seeking time will probably forbid any track movement, though, so it's 
still possible to have up to 164 instruments on a disk. About 16kB seem 
to be the upper (digital) limit for MFM. But then, the outmost track is 
around 55cm long (3.5"*2.54*2*PI) -- at standard compact cassette speed 
instead of 300rpm that's almost 12 seconds.

Rainer