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.

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New conductive ink allows circuit prototyping with a pen and paper


Why spend time etching circuit boards and applying solder masks when all you really need is a rollerball pen and some paper? That’s what University of Illinois professors [Jennifer Lewis and Jennifer Bernhard] were asking when they set off to research the possibility of putting conductive ink into a standard rollerball pen.

The product of their research is a silver nanoparticle-based ink that remains liquid while inside a pen, but dries on contact once it is applied to a porous surface such as paper. Once dry, the ink can be used to conduct electricity just like a copper trace on a circuit board, making on the fly circuit building a breeze.

Previous ink-based circuit construction was typically done using inkjet printers or airbrushing, so removing the extra hardware from the process is a huge step forward. The team even has some news for those people that think the writable ink won’t hold up in the long run. The ink is surprisingly quite resilient to physical manipulation, and they found that it took folding the paper substrate several thousand times before their ink pathways started to fail.

While we know this is no substitute for a nicely etched board, it would be pretty cool to prototype a simple circuit just by drawing out the connections on a piece of paper – we can’t wait to see this come to market.

LEGO printer built without NXT parts

[Squirrelfantasy] built a printer using LEGO pieces. It’s not a Mindstorm project but instead depends on some type of development board and some auxiliary components on a protoboard. We couldn’t get a good enough look to tell exactly what makes up the electronics so start the debate in the comments. We feel this is a printer and not a plotter because the stylus moves on just one plane while the paper feeds past it but that’s open for debate as well.

Guess this answers the question of why aren’t we building our own printers? Some folks are.

[Thanks Haxorflex and many others, via DVICE]

Prison tattoo machine made from PlayStation

Prison inmates have a history of being gruesomely resourceful hackers. The toothbrush shiv comes immediately to mind. One such inmate in the UK wanted to offer tattoos to his fellow convicts so he came up with a tattoo gun using a PlayStation for parts. The crude setup involves a sharpened ballpoint pen and the use one of the motors from the optical drive to move it up and down. The inmate didn’t document his work for us but there are other examples of this method available. Even with modern hardware, ink seems a little 20th century when compared to laser tats.

[Thanks Memmy T]

Pen based input improvements

Lately we’ve been focusing on multitouch technologies, but that doesn’t mean there isn’t interesting research going on in other areas of human-computer interaction. [Johnny Lee] posted a roundup of some the work that [Gonzalo Ramos] and others have done with pen based input. The video embedded above shows how pressure can be used to increase control precision. Have a look at his post to see how pen gestures can be used for seamless workspace sharing and how pen rolling can give additional control.