[sdiy] Embedded micros

[Theo]

Phillips used this method in the 1930s for film and audio recording.
Some Dutch radio stations seemed to have used this system at the time.
I once heard a tape copy of one of these optical recordings.
The quality was really amazing for something recorded 70 years ago, far
better than 78 rpm records.

As for your track separation problem:
Some photo transistors have a really small opening,
placing the photo transistors close to the disk will solve your separation
problem.
You would only need one light source for all tracks.

Making the disk should be easy using paintshop pro, photo shop or the like.
If a 6cm diameter disk is enough you can print the image,
make photos with a 6x9 camera and then cut disks from the negatives.
Fitting multiple disks on one spindle maybe a workaround for the limited
disk size.

With multiple disks on one spindle having one disk for each tone is also a
option.
In this case something like a CNY37 could be used as photosensor/light
source combination.
Solving your separation problem on the way.

Alternatively a photographer may be able to print out negatives of your disk
image on large size transparent sheets.

Just some thoughts,
Theo


From: Dr Strangelove <phdinfunk at hotmail.com>



> There are some formats of movie film that have an optical audio track on
> them, they use photoresitors to translate this optical audio track into
> amp-able waves.  I once thought an organ of some kind could be made by
> making a seet of plastic that had one of these kind of tracks on it for
> every key, more or less whatever sound was desired for that note.  You
could
> have a small motor which turned a shaft and rolled the sheet (which would
> have to be in a loop), over some photo diodes.  It would be sort of like a
> Mellotron.
>
> Later I read that the Optigan uses disks to do something like this, the I
> saw one at the audio playground, they soud pretty cool.  Since you mention
> using drills to drive a drawbar organ, maybe an optigan-like system could
be
> created using a small motor like that.  The only thing I see as a problem
is
> somehow isolating each audio producing track from every other audio
> producing track for photoresistors to distinguish them without somesort of
> bleedthrough.  Also, creating a disk with a bunch of opague to clear
> gradients which were perfectly calibrated to make musical scales at a
> particular rotational frequency would be a bitch.
>
>          -=<Jonathan Pratt>=-
>        (Phdinfunk at hotmail.com)
>
>
>
>
> >From: Glen <mclilith at ezwv.com>
> >To: Paul Perry <pfperry at melbpc.org.au>, synth-diy at dropmix.xs4all.nl
> >Subject: Re: [sdiy] Embedded micros
> >Date: Tue, 21 Aug 2001 00:23:41 -0400
> >
> >At 10:58 PM 8/20/01 , Paul Perry wrote:
> >
> > >I look foward to any synth-diy posts whether they are analog,
> > >digital, or mechanical.
> >
> >Hmm...  Mechanical...
> >
> >That would include what? Making your own reverb plates and springs?
> >Building one's own variable-speed-drill-powered, tonewheel oscillator
> >synth? What else? How about a treadle-powered, mechanically bent and
bowed,
> >musical-saw "theremin"?
> >
> >Am I even close?  :)
> >
> >...but seriously, I DO agree with you.
> >
> >
> >Later,
> >Glen
>
>
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