Two Hard Disks And One DJ Get Down With No Delay

Mixmaster [robelix] built a MIDI controller for DJs that uses two hard drives for scratching and cutting some wicked beats.

[robelix]’s project is called Hard DJ and was inspired by this earlier build capable of producing a droning appreciated chiptune music using the motor inside a hard drive. Instead of reading the out of phase sine waves produced when a hard drive platter is manually rotated, [robelix] used custom laser cut encoder wheels and an IR detector from old computer mice. This gives [robelix] far more resolution than would be possible by reading the drives stepper motors and allows him to scratch and cut to whatever his MC desires.

The electronics portion of the build are a little rough at this stage – just an Arduino Mega, a few buttons, and a trio of faders. [robelix] will be building a proper enclosure for his controller soon, something we can’t wait to see.

If you’d like to clone this DJ controller, all the files are up on the Git. Check out the video after the break.

15 thoughts on “Two Hard Disks And One DJ Get Down With No Delay

  1. i was just about to press submit and suddenly refresh appeared and destroyed my comment… so i’ll sum up quickly. disks should spin, leds underneath should be dimmer and that blue in the case… no words… i know putting leds everywhere you can is cool, but there’s something called good taste… other than that – neat build (sound was too crappy to rate)

    1. pinning discs is definitely something I’m going to try – since the motors are unused yet this should be quite easy.

      The open spaces will be filled with additional controls, then the inside illumination will only be visible through the side panels.

      And sorry for the poor sound quality in the video. My cam seems to have a pretty weak microphone, next time I’ll try to record it directly from the mixing software.

      1. I believe he meant your choice of music, not the quality of sound. If so, I tend to agree. BUT hey, I still like the build, even if the music isn’t to my tastes. Very cool, I’ll be sure to check out the repo.

    1. Using the wheels as capacitive touch sensors is a great idea. Maybe I have to insulate the disks from the frame, should be possible. I’ve got to try this, thanks.

  2. Much more interesting than “control records” and the huge turntable setups.

    And HD motors aren’t steppers, they’re 3 phase, sometimes with hall sensors depending on how old they are.

  3. Just a word of caution. Be careful using harddrive platters for this. The platters of yesteryear were comprised of a aluminum substraight and take well to the kind of abuse they’ll likely see in this application.

    Many disk nowadays use a glass platters. You wouldn’t want to slice up a finger if you got a little overzealous playing with this.

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