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Musical Organ Created From 49 Floppy Disk Drives
ErnieKey writes: A youth club in Germany, called Toolbox Bodensee, has created an unusual musical organ. It is constructed of 49 floppy disk drives all of which combine to play quite a unique sound. It has the ability to be played manually or act as a playback device. If you have a bunch of old floppy drives and want to assemble your own organ, the 3D print files are available for free download on Thingiverse.
49 is the usual number of keys in a four octave keyboard.
In a floppy disk drive there is a stepper motor which drive the read/write heads. That mechanism is used in normal operation to select the correct track/cylinder to read from/write to (a floppy drive is much like a modern hard disk drive in that respect, except the information density is way less and the 'disks' are of course portable).
In the instance of this musical instrument/organ it's 'abused' by letting the stepper motor step with the frequency of the tone you want to play. The friction between the read/write heads and the rails they are gliding over makes the whole floppy housing vibrate a bit with the selected frequency. The housing acts as a resonance box and the vibration is transferred to the air where it produces sound waves in a frequency (the same the stepper motor vibrates with), you can hear.
Because the stepper motor doesn't rotate smoothly but in steps (hence its name) the produced sound is rather 'sharp', 'blocky', or whatever you may call it (I have some difficulty here finding the correct musical jargon - English is not my native language). There are a lot of higher harmonics in it.
Maybe if you saw the video in the original article, you noticed some random gaps in some of the notes played, where, if you knew the pieces played (they are rather popular numbers so I'll assume you know at least some of them), you would expect the note to continue. Those are caused because the head has reached the end of the track and now has to reverse (and so does the rotation direction of the stepper motor). That takes a moment in which no 'music' can be played.