66% or better

[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.

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Putting multitasking on an AVR

[vinod] wanted to familiarize himself with AVR assembly programming, but wanted to do something a little more ambitious than simply blinking an LED. While the completed build does blink a few LEDs, we love that e decided to implement multitasking on his microcontroller.

The program [vinod] came up with uses round robin scheduling to give one of the seven programmed tasks a little bit of compute time every time a timer is triggered. Although it’s extremely simple compared to “real-life” real-time operating systems like VxWorks, it’s still an impressive achievement.

In the video after the break, [vinod] shows off his task-switching with seven LEDs. The white LED is a PWM task, while the six other LEDs are simple toggling tasks  that switch a LED on and off at set intervals independent of each other. This would be hard – if not impossible – to do without some sort of scheduling. Nice work, [vinod].

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Turning a rotary tool into a PCB drill press

Drilling holes in PCBs is nearly always an exercise in compromise; the holes are small, precision is paramount, and the common solutions, such as a Dremel drill press, aren’t of the highest quality. In a quest to find the best way to drill holes in PCBs, [reboots] even went so far as to get a pneumatic dental drill, but nothing short of a high-quality micro drill press would do. Not wanting to spend hundreds of dollars to drill a few holes, [reboots] did the sensible thing and made one from scratch.

[reboots] ended up buying a Proxxon Micromot 50 after reading the consistently good reviews around the Internet. To use this rotary tool as a drill press required more work, though. Two precision steel rods from a dot matrix printer were salvaged and pieces of aluminum C-channel and small bearings were bolted together into a very high-precision drill press. Only hand tools were used to build this drill press, and the results are amazing.

[reboots] was originally inspired to check out Proxxon tools from one of Hack a Day’s rare tool reviews. The Proxxon TBM115/220 earned the skull ‘n wrenches seal of approval (and found its way into other Hack a Day-ers labs), but sometimes a few hundred dollars is too much of an investment for something only used occasionally. Considering [reboots]‘ scrap aluminum drill press is a better tool than the sloppy consumer rotary tool presses, we’ll call this a success.