Power to the little people

Unobstructed by corporate bulk and bureaucratic red tape the little guy seems to be consistently coming up with seriously dope shit. Take this gentleman here who was disappointed with the quality of jog wheel controllers that the current crop of dj companies with millions of dollars in development money had produced. So, as most people have been doing around here at Dj TT, he made his own- but better. Bookyakasha ninja midi master.

First, you need to see this thing in action. Yes, the video is delayed but the performance of his device is spot on.

Next, check out how the well he got the touch sensitivity to work.

To achieve this performance he wisely included a Vestax CF-PCV crossfader.

Here Dj Raseri describes his method for achieving a damn good jog wheel on his midibox page.

After considering a number of options, I settled on an optical quadrature wheel design. This consists of two photodiodes spaced slightly apart, and a wheel with a pattern of slits round the circumference. By watching the slits go past the photodiodes, you can determine the speed and direction of the turning wheel. Wikipedia has a good page on this.

Old (ball) mice use this exact technique. Which is handy, because if you have any old mice lying around, you can harvest them for optical sensors and LEDs. This is what I did. You can rig up something out of individual photodiodes and an infrared LED if you prefer.

An optical encoder wheel can be made using a transparent acetate sheet and a laser printer. Draw up a pattern using your favorite CAD program, print it onto the sheet, and cut it out.

I put the two photodiodes into two voltage dividers and wired them into pins 3 and 4 of the PIC. At the moment I just have the optical encoder wheel sitting on a spindle, with a CD mounted on top for easier grip. This is obviously a bit wobbly but it works fine for testing.

jog wheelTips
Comments (8)
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  • DigitalMasterTaco

    frikkin sweet! if i can make a request: pls make an mp3 decoding cdj that can read the tags and get a bpm. that make an auto-bpm-match button. kinda like in traktor dj studio.

    you guys probably have all this built in other pages of your site but since im at a job-workforce thingy where I can only use the net for applying for jobs, I might get banned just for writing this.

    I need a pair of tables, cd/mp3 type and I don’t have much cash (none really), but I am a dedicated and excellent DJ of the breakbeat and psytrance nature. I just need to equipment and I would love to build my own. pls pls pleeeaaassseeee help me out guys, I’m going through DJ withdrawls since I moved to LA and I’m broke. could you send me some links on djtt.com so I could build my own tables. that would rawk!

    thanks ahead of time.

    DJ Tak0

    nico: try using waxpaper on top of the slipmat.

  • ernandes


  • midifidler

    Hmmm, something like this but with a motorised platter driven with a stepper motor by the midi clock, and optical encoding on both the platter and the vinyl. And all alloy construction… I think I've found my next project 🙂 Now I just need to finish off those midi-fighters…

  • nico

    I guess you can scratch with MIDI after all then, never mind the jitter! So simple an idea, it's absolutely lovely. Never really got into scratching, the needle always jumped, the slipmat was sticky. This made me want to try it, I want one!

  • DJ ToS

    shuebox is for prototyping. 🙂

    Anyway, next step is to create a rotating platter that detects slowdowns and speedups instead of touch-sensitivity.

    It is noted that midibox-native touch sensing doesn't work well if you have dry hands(might represent a problem). This is a nice project BUT as M.Haque from applegeeks would say: http://www.applegeeks.com/comics/viewcomic.php?is
    "Needs more boobs."

  • obsidiance

    hahaha at the flux capacitor!

    very dope sh*t indeed! this is the kinda stuff that gets me excited! lovin the shoebox technology!