DIY Scratch Controller


There’s something viscerally pleasing about simple solutions. [Kip] came up with one in the form of a scratch controller. The spindle from an optical drive is used to hold a CD in place, which acts as the LP for scratching. The sensor from an optical mouse is mounted upside down below the CD and detects the rotation of the disc. From there it’s just a matter of setting up your software to get the reading from that mouse. He’s had some trouble finding disc surfaces that the mouse sensor will read reliably.  We’d recommend trying some of those stick-on inkjet CD labels.

This is similar to a scratch controller we saw in 2008. That one was actually repurposing the IR encoding from inside of a mouse. We’re not sure which method would work better, but either controller will make a nice addition to a Flexi Knob setup.

38 thoughts on “DIY Scratch Controller

  1. Breaking News Folks!!!!!!!

    We have a new champion for the dumbest, dullest, stupidest video here on Hack-a-Day.

    This one rushes to the top in a category all it’s own.

    So good work “scratcher guy” you’ve made it to the top (or bottom) of the tremendously bad video pile.

  2. @chris but you can’t argue with the fact that 5mins is really not an appropriate video length for this kind of hack, as it should only take 5mins in total to disassemble the CD drive and mouse and assemble this hack…

    but it should be possible to do this without the mouse: stop the drive’s motors, and analyze the data the laser reads. it should work like an optical encoder… (I guess there are alignment patterns in CDs somewhere?)

  3. 1. A youtube concept video is not a hack.

    2. Until you show it working, it’s a broken-ass CD player and mouse, not a scratching device.

    3. I know of zero programs for DJing that would let you use the mouse like that to scratch, not to mention having to hold down a mouse button for the ones that do.

  4. I don’t know, but isn’t it possible to use the motor as a generator and from there see how much movement there is? You could make the device a lot smaller then, and removing electronics (if the functionality doesn’t suffer) is never bad :)

  5. Persistence – that and a tough skin is what success is all about – good followup (although you’ll need a time machine or a doctors note to erase the first vid from everyone’s mind).

  6. A much more elegant way of approaching this would be to analyze the voltage pulses what would be produced by spinning the rotor of the drive motor with a disc glued to it. Of course that would involve some processing and unless you fed it into your sound card, some sort of micro-controller to convert into a usable input device.

    That said, this is a much easier way of doing it and does have the advantage of working as USB HID out of the box.

  7. Yeah it was just made to be a stupid-simple controller and the A.D.D. was not gonna let me put any actual thought in to it (and apparently not my first video either) SORRY AGAIN EVERYBODY !

  8. Yeah. I would have to say that I thought it lame that there was no demonstration of it’s actual scratching. But I am GLAD the powers-that-be behind hackaday seem to NOT be some technocrati 31337 snobbos. They seem to have a good sense of humor and I come to this site daily to lubricate the folds of my brain.

  9. Great hack Kip! For v2 you should see if you can build a good housing for the motor and board. Very creative repurposing of a mouse. Also, you could see if you can get access to the left and right buttons, and maybe the jog wheel, you could really expand on this initial hack.

  10. Soooo….is there any functionality demo’d in a video somewhere? Just looks like something a 5 year old slapped together. Next project he built was a robot made out of cardboard boxes and tinfoil.

    Seriously, where’s the functionality?

  11. Ah, come on guys&girls! Give the guy a break! Sure, the video above is not worthy an Oscar, but is it his hack-skills or his presenting-skills that is the primary concern on a blog like this?

    Second, just because a hack is simple/easy to implement and recreate doesn’t automatically mean that is bad/not a hack/not worthy of this site. Some of the greatest inventions are also very simple. Thinking out of the box and repurposing the components of everyday things is, IMHO, an extraordinary feat not to be ridiculed with like this. You guys are complaining that he’s not even using an Arduino, I could just as well complain that you are noobs for wanting exactly that. Why not build your own uC with ICs from the 74- and 4- series?

    It’s a matter of perspectives and I believe it is a good thing that we can abstract ourselves from the very lowest stuff nowadays. Look at the impact of the stuff from Arduino, Sparkfun, Phidgets etc. Look at all the stuff that has been created with it, look at all the creativity is has enabled to be channeled into real stuff. But no, I guess it is not haXXor enough for some.

  12. PS,
    in the comments, he posts the link to another video where he demonstrates the functionality of the thing.

    And Kip, nice work! Thanks for sharing it with us. =) Keep up the good stuff and try new things!

    And, to further elaborate on the above, SMS is a good example of where people took something meant for one thing (originally, SMS was meant to be used for technicians in the field) and with no or little change repurposed with huge impact as a result. Now, this is not one of these, but perhaps a small increment on something that already existed, but it can serve many purposes. To me, it was a fun read and inspiration. Maybe this will spark a great, novel idea in someone?

    I’m done now, arguing on the internet is like booing in the special olympics…

  13. Alright guys/gals I know the vid sux..I gave it a band-aid so hopefully that will appease some of the not so savory characters leaving crappy comments. And for those of you who did post crappy comments on my crappy video:
    I hope you never make a mistake because I will be shore to not ever let you hear/read the end of it.

  14. what the hell guys, this is not lame – it really made my day! seriously! not because of the build quality or using mouse for scratching but using the cd spindle! cheap and easy way to make perfect jog wheel.

    I already started to build my own

  15. I agree with anacron and I would love to see where other people go with this idea as I added a few minor things that I cant live without now. also using it with traktor scratch pro lots of fun so far
    thanks mate cheers!

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