The Atomic-Powered Robot

[Image: A black toy robot standing next to a My Little Pony. The robot has golden ears and arms, a speaker on its chest, and a big round button on top of its head. On its belly, it has a symbol referring to nuclear power. Text around the robot says OMNI, 024-2931:1524, and 2 MODEL-B.]

This is my mechanical baby, Tommy. He's an atomic-powered [sic] robot that can talk and walk around the room. Born in 1984, he's been with me since the early 1990s, but for the last ten years he's been quite ill and not able to talk.

Today I finally fixed him. While doing that, I decided to do a full autopsy for the sake of science, as I've found his vocal cords especially intriguing. So please observe: Tommy's internals. (As with all medical imagery, it's not for the faint of heart.)

Tommy's belly is dominated by a pink-colored contraption that looks like it has a speaker on the front. The pink device gives Tommy his ability to utter the words "I am the atomic powered robot. Please give my best wishes to everybody!" and also make the sound of a laser gun. Below the sound player is the walking motor, which is quite simple and I'm not going to concentrate on it.

[Image: The robot opened up. A bunch of wires go from inside its head down to where its feet are, where some gears can also be seen. In the middle, a big pink box with a speaker in the front.]

Removing the cover of the pink device, we see a large funnel-shaped object that looks a bit like a speaker. It has a tense plastic membrane, like a drumhead.

[Image: Inside the pink box, a peculiar speaker with a translucent membrane.]

Now it gets really interesting. The speaker is resting on a tiny gramophone arm, which is playing a little vinyl record! There's even a simple electro-mechanical end-of-disc detection and arm-return mechanism. The vibrations of the needle are mechanically transferred to the speaker membrane; there's no electric amplification of any kind.

[Image: Still inside the speaker box, a slit reveals a little vinyl record underneath. A gramophone arm and needle are resting on it. Towards the end of the disc, there's a switch that seems to close an electronic circuit when the arm moves far enough.]

Could a gramophone record get any cuter?

[Image: Close-up of the disc being held in the author's hand, removed from the box. The disc is small enough to fit on the palm.]

And here's Tommy sending you his best wishes.

UPDATE: Okay, yeah, he's cute and all. But take another look at the above photo of the record. Don't you think it contains a lot of information about the recording? Perhaps you could even extract the audio from a good enough photograph. Just a silly thought.

Well, let's get to it.

First I'll need a good quality picture of the record's surface. My roommate lended me her expensive camera for this purpose. To get the rough surface evenly exposed, I used an exposure time of 10 seconds with an aperture of f/32. I circled a lamp around the record for 10 seconds and got this cool image.

[Image: A high-resolution photograph taken tangentially towards the record. Grooves are clearly visible as darker lines, and even the recorded signal can be seen as oscillations in the grooves. The end of the record seems to be silent.]

I'll hint the positions of the groove at every turn and then let Perl interpolate a smooth spiral:

[Image: Screenshot of Inkscape with the above image loaded and markers drawn on the spiral groove wherever it crosses the pi radians mark. Next to it, a computer-generated spiral with similar spacings.]

I'm going to read the record along the spiral at 360 RPM and just convert the pixel brightness at every point of the groove into PCM amplitude. This will probably result in something audible, although quite noisy. There appears to be two interleaved grooves: one for the speech, one for the laser sound. The groove gets randomly selected when the robot's head button is pressed, depending on where the needle happens to land. So I made a stereo sound file.

It's very noisy indeed and there's a lot of crosstalk, but something can be heard in the background. After edge detection on the image and some noise removal on the audio:

Update: Further studying of the record and better sound samples in "The laser-equipped Lego train".


  1. Hats off to you, that's some awesome work there. This is just begging to be scaled up full size 7"/12" vinyl.
    Just wondering if approaching it slightly differently, and spinning the record, taking an image sample at many intervals and reading that, so as to avoid aliasing, would give any improvement. As opposed to rotating the light source, then scanning in a circular fashion around a square image.

    1. I've thought about that. It would of course need more images to be taken. Also, I've pondered on scanning it with a laser.

  2. Awesome post and update! Looks like there's "width" information at every point in the groove. Maybe you could measure intensity along a line perpendicular to those blue overlay marks you've superimposed on the image. Then you could extract the "width" of the bumps along the groove and translate that to amplitude? I suppose you would need a higher resolution image though otherwise it seems like you would only get like 3 bits of information per sample!

    1. I tried translating the width into amplitude, but it was noisy as well! I was able to extract more than 3 bits by subpixel interpolation, though.

  3. This is ridiculously awesome, I did not know there were tiny gramophones like this one inside vintage toys(if I only knew back then...). This calls for alot of different mods and improvements to the design and features of this toy! Awesome work!

    (off to ebay to get a shitload of this little gramophone designs)

    1. Indeed, though I'm too attached to this particular robot to start making invasive mods :)

  4. "A toy robot!"

  5. Hey, won't a high res scan of the disc using a flatbed scanner be a better way to do this?

    1. There are two downsides to this: 1) I don't have a flatbed scanner 2) Flatbed scanners use a sweeping line scanner and a linear light source, whereas the disc is circular, so the irregular shadows and other distortions would probably be similar to those in this photograph.

  6. Mielenkiintoista..
    Kannattaa muuten avata tuota aukkoa hieman, että ei tule niin ikävästi diffraktiota (tai aliasingia, miksi sitä haluaakaan kutsua) ,

    Jos haluat käyttää pitkää valotusaikaa minimoimaan sulkimen aiheuttamaa tärähdystä (tai no peilihän siellä lonksahtelee enemmänkin), kannattaa joko
    a) ottaa kuva peili lukittuna auki-asentoon tai
    b) varustaa kamera ND-suotimella (harmaasuodin, jolla voidaan keinotekoisesti himmentää kuvaa )
    molempi parempi

    Kannattaa tuon lisäksi ottaa kuva joko kaukosäätimellä tai ajastimella, jotta kamera ei tärähdä laukaisimen painamisesta.

    Kuva on yleensä tarkimmillaan himmennettynä n. f/5,6 - f/9 välillä, riippuen käytetystä objektiivista. f/32 on mielestäni aika rankasti liikaa.

    Lisäksi kun katsot käyttämäsi objektiivin vääristymien ominaisarvot ja korjaat ne photoshopissa, niin saat parhaan mahdollisen tuloksen aikaiseksi.

    Myös HDR kuva vois olla aika toimiva.

    1. Kiitos näistä. Käytin pitkää valotusaikaa, jotta ehdin valaista levyn tasaisesti joka suunnasta. Ympyräsalamaa tms. kun ei ole.

    2. After fixing my own non-functioning Tommy robot today, after him resting in a box for 20+ years, I found your post very interesting. The arm-return mechanism had merely dislodged and as he cannot move while 'talking', he just did nothing. Half hour of fixing and a happy ending all round for the atomic robots of the world! Read online he is a 70's retro guy too...

  7. i just bought a tommy robot in eaby and i need help to fix it.... thanks for your space... grettings from mexico.

  8. That's fascinating stuff. The record reminds me of the "See N Say" toy I had when I was a kid. That was unique as it was entirely mechanical, you pulled a string to wind it up. Naturally I took it apart :)

  9. Greetings from Serbia. Today I bought Tommy Atomic on a local auction web site, got him home, and did not get up until it was functioning like his first day. Kudos to Oona for her inspiring work and play, girls that love robots and play with technology are too rare, I wish we had at least one in each neighborhood!-)

  10. Any one knows the difference between the two versions of this robot…one that says 2002 VS the one that says OMNI ?


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