No-touch music player


This little box not only plays tunes, but it lets you control several aspects of playback without touching a thing. [Thomas Clauser] calls it the LighTouch and we like it because it uses inaudible sound to control audible sound.

We think the pair of cylinders sticking up through the top of this project enclosure will be recognized by most readers as the business end of an ultrasonic rangefinder. This is the only control interface which [Thomas] chose to use. Although he didn’t write very extensively about the specific control scheme he implemented, the video embedded in his post shows some of the gestures that cause the Arduino inside to change its behavior. For instance, a swipe of the hand at higher level starts playback, swiping at a lower level pauses it. When adjusting the volume the box responds to how close his hand is to that sensor. With this control in place, the music side of these things is simply handled by a music shield he is using.


  1. Veda says:

    Looks like he can only control the volume…

  2. Alex Rossie says:

    Most ultrasonic transducers make sound actually.

  3. Thanks to Hackaday picking up my post. Lately I’ve had very limited time to properly document, but since you took the time to do a writeup, I’ll make the time and do it right!

  4. fajita says:

    geez. this is brilliant. i listen to podcasts in my car, and i hate fumbling around trying to skip to the next episode or 30sec skips.

    hand gestures is brilliant. great find, HaD!

  5. Ren says:

    Sort of like a next generation theremin…

  6. (update to post)
    Here’s the current control scheme:

    0-7cm = Pause (LED OFF)
    7-30cm = Lowest Volume->Highest Volume (LED DIM)
    30-50cm = Highest Volume (LED ON) (dead zone)
    50-55cm = Next Track (LED OFF then ON)
    55cm+ = Take no action

    So basically the setup works based on your hand’s distance from the sensor with feedback given by the LED so you know where you are in the control scheme. There’s ‘dead zones’ setup to avoid accidentally moving from volume mode to next track. For instance, once you’re at the max volume (30cm) , there’s a +20cm dead zone until you hit the next track and the LED turns bright so that you know you’re at the max volume.

    Whenever you move your hand away, and the distance becomes ‘infinite’ (ie, the ceiling) it locks in the last distance it recorded for your hand. So basically you move your hand to the volume you want, then slide your hand off to the side to lock it in.

    To pause, move your hand close to the sensor until the LED turns off, then slide your hand away.
    To change volume you raise your hand up or down while the LED is dimly lit, until it’s brightest (then you’re at max volume)
    Once you’re at max volume, you can pop your hand up, watch for the LED to turn off, then back down to move to the next track (then you’re back in volume mode, or just move your hand off to the side).

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