Rabiscoscopio – Oscilloscope Drawing Made Easy


If you own an oscilloscope, sooner or later the urge to see something other than signals on the screen will strike. Some people ignore the urge and go about their normal business while others give in, spending hours carefully crafting images, games, and more. The process is time consuming and tricky as our own [Kevin Dady] discovered, but rewards come in the form of geek cred and are hard to pass up.

[Alex] wanted to draw on his oscilloscope, but decided that he would try something other than the microcontroller-based solutions we have seen in the past. He figured the easiest and most accessible way to draw on the scope was with sound, so he whipped up a small application he calls Rabiscoscopio to do most of the work for him.

He starts off by drawing an image using a single line, saving it as an SVG file. This image is converted into an audio file by Rabiscoscopio, which can then be fed directly into his oscilloscope from his PC. That’s all there is to it – it really doesn’t get much easier.

While you could claim that [Alex] is cheating his way through the oscilloscope drawing process, we think his application rocks – after all, hacking is about making your technology work for you rather than the other way around.

Give Rabiscoscopio a try and post the results here or in our Flickr stream – we’d love to see what you guys come up with.

In the meantime, check out the video below to see [Alex’s] attempt at replicating the Garoa Hackerspace logo on his scope.


23 thoughts on “Rabiscoscopio – Oscilloscope Drawing Made Easy

  1. There’s no “cheating” in hacking. A hack is already a kind of cheat!

    Let’s not get sad just because, after this project, nobody will ever need to create complicated circuits to draw on a oscilloscope :) We can focus our creativity on other things, from now on! :)

  2. so cool… I’ve been pondering on this idea for years– an application that will take a vector drawing and create an audio file that will draw just like this. downloading and trying on my own tonight! even if it means oversleeping and being late for work!!

    1. @M4CGyV3R
      yes, the audio in the youtube video here is what that image sounds like, though with youtube compression, piping that into your own scope isn’t going to look nearly as sharp. check out the dalpix page on this project for the audio file they provide that I believe they used.

      @The Timmy
      so I dug out my laser and x/y galvo dealy and gave the software a try… long story short, I think I need to go back to the drawing board for my project, but I still really like [Alex]’s work here and will further check out what he has to offer, as time allows.

      for my results, you can check out my post here:

      1. Saw your results, not bad. I wondered if you dropped the pitch, would this cause it to draw slower or have more deflection? I would think a volume (=voltage) change would determine the deflection amount and cause larger images.

    2. @Trav
      yeah, I played with the volume levels and pitch a bit, trying to get better results. slowing it down does help, but even at 10% speed, it’s still no where near viewable as intended.

      blindly controlling mirrors on voice coils just isn’t the way to go about drawing anything more than seemingly random scribbles. though, sending low frequency sine waves seems to work ok, but I got another laser project that does that better.

  3. I did the same thing some time ago, though it was tricky to construct a wave that produced a good image even after being run through the sound card’s band pass filter. I made animations as well. For extra fun, take these sound files and use them as samples to include in electronic music. They sound like any other note, but if someone’s clever enough to connect their stereo to an oscilloscope, they’ll get some, shall we say, bonus content.

    1. Aphex Twin’s done a similar thing, search for “Aphex Face”. He encoded his face in a spectrograph of one of his songs, a time / frequency plot shows it. Also known as “voice print” on the old ver of Winamp. There’s software on the net that can convert bitmaps into it.

      This is a bit different, tho I believe Mr Twin did it too, one of his songs gives spirals if you hook the stereo output to an X/Y graph. But this takes it a step further! Lots of potential here! There’s bands that put in features that remain hidden for years.

      1. Aphex Twin also put a series of tones at the end of the song ‘Window Licker’ that makes the graphic equaliser display on your sterio/winamp do a badass looking looping ‘mexican wave’ type animation

        The band Super Furry Animals, released the first album mixed in 5.1 on DVD, if you hit the view angle button on your remote there is a hidden 5.1 scope visualization that displays the sound as a circle on a 2D plane.

      2. http://www.youtube.com/watch?v=M9xMuPWAZW8 here too, that’s also AFX.

        One simple effect I always liked was the hidden track on Apoptygma Berzerk’s Welcome to Earth: http://www.youtube.com/watch?v=6rGivsH2X1w . Play the song in mono and see what happens. Aside from the great chiptune sounds and the fact that it’s hidden, I noticed that in XMMS the waveform shows as flat. A friend remarked that the weird sound was characteristic of something that’s 180º out of phase. Sure enough, playing it in mono mixes the two channels together leaving silence… except for the hidden message, lying dormant within the hidden track. Very cool. Give it a try.

    1. Despite not accepting curves, you can still draw curves and bezzier on InkScape normally. When you finish, just use the curve selection tool (The second from up to down on tool selection bar) and select the whole curve.

      After that, just hit the 11th button on the curve tool special toolbar (The one that appears when you hit the curve tool button at tool selection bar). This button will convert all curvces, circles, bezzier, etc, into a series of connected lines.

      (Sorry. I hit the wrong button. I was gonna REPLY this commen but wrongly hit REPORT comment. Sorry. It’s late night!)

  4. I just don’t get why people want to “play” on their expensive scope instead of just using their monitor or TV. Okay children, your scope is for doing useful work not burning silly images on the screen.

    1. A scope is little more than a CRT tube with a variable rate sawtooth generator on the X axis. In this project, he’s feeding X and Y directly, bypassing the sawtooth generator, basically using the scope as a raw tube. You could easily achieve the same effect on a TV CRT, feeding each deflection coil with the outputs from any reasonable power audio amplifier. Take the audio file generated from this project and play it through the amp, it will work.

    2. Heh. I have recently developed quite a fondness for vintage scopes.

      Some of us are really paranoid about the CRTs on our scopes. Perhaps with good reason – I just sold a tek 22xx after nearly a year of not being able to find a replacement crt.

      I’d love to use a scope as a clock.. but oh man, I could never get over the anxiety about burn-in and waste. Though if I had a scope that had a crt that was already burned or otherwise damaged, then that’d be okay.

      Surely a little fun painting images on your scope will not abuse or damage it.

      How about tweaking the hack so that the image painted floats around the screen, like a screensaver?

      Here’s another perspective… Scopes should be regularly powered up. It arguably helps keep the electrolytics working. Though it doesn’t exercise the knobs and switches. I suppose someone who saves old scopes(*) could rig up one of those x-y clock driver boards to drive all of their scopes simultaneously. At a scheduled time, all of the scopes could be turned on via timer as part of a weekly burn in. It would be pretty neat to see a bunch of vintage scopes light up with clock faces for one hour a week.

      * – preserving old analog scopes is important. They really don’t make them like that anymore. It’s important to keep them working, and to save the spares for other folks to use. There is, however, the risk of becoming the equivalent of a “cat lady”. I’m not sure what the proper title would be? Old Scope Dude?

  5. No one has mentioned YouScope yet? Easily the most impressive use of the soundcard-to-oscilloscope technique. http://www.youtube.com/watch?v=s1eNjUgaB-g

    Using an audio output has its drawbacks; modern devices have a low-pass filter on the output that limits the bandwidth (and the drawing capabilities). I’ve never been able to achieve a Youscope picture that’s as clear as the one in the demo.

    Here’s the raw audio file: http://kapsi.fi/~jpa/stuff/other/youscope-wave.flac

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