[Dino]’s One-year Extravaganza Is A Laser Oscillograph

Readers of Hackaday may have noticed the weekly posts featuring whatever [Dino Segovis] of Hack A Week has cooked up in the last seven days. For [Dino]’s one-year anniversary, he’s pulled out all the stops and put together one of his coolest hacks to date. It’s a laser oscillograph that projects waveforms on a screen just like an oscilloscope. What’s more, the entire contraption is built out of a dead hard drive and a few motors and mirrors [Dino] had lying around.

The build uses an old hard drive to draw the vertical component of the waveform. Because hard drives usually use a voice coil to move the heads around the platter, it’s very easy to connect a hard drive directly to the headphone output of [Dino]’s laptop. Playing a sine wave on his computer makes the drive heads move up and down, but [Dino] still another dimension. For that, he used a rotating mirror that reflects the wave onto a paper screen.

[Dino]’s finished build isn’t that much different from an oscilloscope or projection TV. It’s possible for [Dino] to improve upon his build and make a genuine vector display with the addition of additional electronics and optics, but we’re not expecting that until at least the two-year anniversary.

Check out [Dino]’s build video after the break.


13 thoughts on “[Dino]’s One-year Extravaganza Is A Laser Oscillograph

    1. Wow, that’s a pretty innovative way to mount the vertical axis mirror (to the frame of the hard drive, hinged and linked to the read/write arm) … then you use the platter motor to do the vertical axis. This is cool because once you get it aligned it stays aligned (more or less).

      Yes most new ideas have already thought of… kind of sucks when you are trying to invent something new, but for hacking… it doesn’t really matter because it’s the ACT OF DOING THE HACK that is the real reward. I love to build and hack things, even if I copy bits from here and there. It’s fun.

  1. Bravo Dino! What a cool project to finish off your series with. I admire your persistence at completing a Hack A Week. Understand the need to stare into a camp fire for a bit and in general, balance your time with other projects not on a deadline. You have set the bar high COMPLETING a hack a week. For the Love of Hacking, I hope you continue to PUSH FAST AND FAIL! Go Dude!

  2. Why did you glued the laser to end of armature? I guess you can achieve better performance with laser/mirror glued somwhere near the centre of rotation (note that angles will remain the same while being at smaller lever)

    1. By taller you mean more deflection angle. Therefore you need to mount laser or mirror as close to the center, for 2 reasons. First; the speed that the voice coil arm can move is limited by mass out away from center, think flywheel. Cut the arm off and file the side of the block of metal flat, securely mount mirror on flat. Second; the angle of deflection is double (you quoted the rule) with a mirror which also has less mass and needs no wires added to the flexing.
      You will need to move a three or four sided mirror on motor closer to voice coil mirror, it will mount all on the HD case. Just cut the sides off. Ditch the motor and use a second magnet-mirror asy at right angle and you can have x-y scope. I started this way on the way to build a wall sized scope that could have tuning pitch as the timebase, so from anywhere you look you can see to tune up.

  3. Hard disk drives are actually expensive first surface mirrors. Conventional mirrors actually reflect more than two beams from a single incident beam, due to internal reflection. First surface mirrors only reflect one beam.

    1. Exactly!

      Dino: I would suggest you to cut a piece of the hdd disk and glue it to the hdd arm to make a mirror where you can shine the laser to, instead of mounting the laser directly into the arm. I suppose the arm will get lighter and maybe for that reason you can get a better frequency response at higher frequencies.

Leave a Reply

Please be kind and respectful to help make the comments section excellent. (Comment Policy)

This site uses Akismet to reduce spam. Learn how your comment data is processed.