Synthesizing sound with a light sensitive pen and CRT television

Here’s the latest project from [Niklas Roy's] workshop. Lumenoise is an audio synthesizer controlled by drawing with a light-sensitive pen on a CRT television.

The pen is a self-contained module which connects to the TV via audio and composite video RCA plugs. Inside the clear pen housing you’ll find a microcontroller which generates the audio and video. The business end of the pen contains a phototransistor which lets the ATmega8 take a reading from the video screen. Since the chip is generating that video signal, it’s possible to calculate the pen tip’s position on the screen and modulate the sound output based on that data. You can watch a recording of the results in the video after the break.

This is a very simple circuit to build, and [Niklas] makes the point that most of us have a CRT hanging around in a dark corner somewhere. We think this would be a fantastic¬†soldering¬†project to do with the kids, and that this would be right at home as a children’s museum piece because of the wow factor involved in playing around with it.

We can really tell from this and some of his past projects that [Niklas] just loves the 8-bit audio.


  1. aztraph says:

    it’s an 8 bit wonderland!

  2. mjrippe says:

    I love it! I just wish the video showed him drawing these sounds so I could understand the gestures used to create them…

  3. Munch says:

    What’s old is new again. Viva la Light Pen!

  4. M4CGYV3R says:

    It reminds me of AudioSurf from 1985.

  5. Clancularius says:

    I like the “old is new again” comment.

    This reminds me of an audio piece I heard recently about Oramics, a “drawn sound” technique developed by Daphne Oram in the late 1950’s.

    Check out and

  6. Mike says:

    Fairlight CMI, anyone?

  7. Motorcyclist says:

    John Cage, eat your heart out!

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